Education EDF 621 Week 1 Assignment

Systematic Review

The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

G. Fynn,1 M. Porter,1 T. Borchard,1 C. Kazzi,1 Q. Zhong1 & L. Campbell2

1 School of Psychology, Macquarie University, Sydney, New South Wales, Australia 2 School of Psychology, University of Newcastle, Newcastle, New South Wales, Australia

Abstract

Introduction Individuals with intellectual disability (ID) are at higher risk of experiencing difficulties with anxiety than the general population. However, there are major barriers for individuals to receive appropriate services. There is a growing understanding of the importance of developing appropriate psychological interventions for this group. The objective of the current review was to systematically evaluate the findings of studies investigating the effectiveness of cognitive behavioural therapy (CBT) for individuals with ID and anxiety. Another aim was to explore which adaptions to CBT and treatment components were currently being utilised within the field. Method The electronic databases of CINAHL, EMBASE, Medline, PsycINFO, Psychology and Behavioural Sciences Collection and Scopus were searched to identify relevant studies. The methodological quality of these studies was assessed using established quality assessment tools by the

National Institutes of Health for pre and post studies and case series. Results Nine studies were included in this systematic review, all of which reported improvements in anxiety severity for some participants (25%–100%; N = 60) following CBT. Only three studies reported moderate effect sizes for CBT interventions on anxiety for individuals with ID. Discussion and Conclusions There is emerging literature supporting the effectiveness of CBT for individuals with mild ID. Findings highlight that CBT for individuals with anxiety and mild ID, including cognitive components, may be feasible and tolerable. While the field is gradually receiving more attention, there are significant methodological flaws present, which limit the conclusions that can be drawn regarding the effectiveness of CBT for individuals with ID. However, there is emerging evidence for techniques such as cognitive restructuring and thought replacement and modifications such as visual aids, modelling and smaller groups based on this review. Future research is warranted to investigate whether individuals with more severe ID can benefit from CBT, as well as further exploring what are the necessary components and modifications.

816

Correspondence:

A/Prof Melanie Porter, Room 3.519, AHH, School of Psychology,

Macquarie University, Herring Road, Sydney, New South Wales

Australia 2109.

(e-mail: [email protected])

Journal of Intellectual Disability Research doi: 10.1111/jir.13046

VOLUME 67 PART 9 pp 816–841 SEPTEMBER 2023

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits

use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial

purposes.

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Introduction

Individuals with an intellectual disability (ID) are at greater risk of experiencing mental illness at all ages, compared with the general population (21.7% vs. 4.3%; Hughes-McCormack et al. 2017). Nonetheless, anxiety is underdiagnosed in the ID population due to diagnostic challenges (Hsieh et al. 2020). First, people with ID are less able to self-report anxiety symptoms due to expressive communication difficulties (Scott & Havercamp 2014); second, anxiety disorders may wrongly be attributed to pre-existing ID (i.e. diagnostic overshadowing; Reiss et al. 1982). This lack of diagnostic sensitivity impedes appropriate treatment.

Individuals with an ID are at greater risk of developing anxiety due to various factors, such as an increased number of stressful life events or chronic health conditions (Hsieh et al. 2020), and they may have limited psychological resources to cope with adverse experiences (Taylor et al. 2008). Moreover, several neurodevelopmental conditions with comorbid ID are associated with elevated anxiety, such as autism spectrum disorder (ASD; van Steensel & Heeman 2017), Fragile X syndrome (Cordeiro et al. 2011) andWilliams syndrome (Kozel et al. 2021). Despite this, there is a lack of evidence-based approaches in clinical practice and limited expertise and confidence of professionals working with people with ID and concurrent mental health difficulties, which may contribute to the difficulties accessing appropriate services (Unwin et al. 2016).

Historically, there has been an overreliance on medication and behaviour modification when treating mental health difficulties of individuals with an ID (Whitehouse et al. 2006). It was commonly asserted that psychological therapy involving talk therapy or cognitive components was not appropriate for individuals with an ID due to their cognitive deficits. However, this notion has been challenged, and there is growing recognition that individuals with a cognitive impairment, including an ID may benefit from psychological treatments, such as cognitive behavioural therapy (CBT; Taylor et al. 2008). Indeed, the clinical guidelines published in the UK recommend CBT for individuals with milder ID, to

treat depression or subclinical depressive symptoms (National Institute for Health and Care Excellence 2016).

There is a wealth of research on the effectiveness of CBT for anxiety disorders in the general population which include social anxiety disorder, specific phobia, generalised anxiety disorder (GAD), obsessive–compulsive disorder (OCD) and post-traumatic stress disorder (PTSD). CBT may be conceptualised as a class of interventions that are collaborative, structured and skills-orientated, which focus on the interaction between thoughts, feelings and behaviours. It involves attempting to modify unhelpful thoughts, behaviours or both to improve emotional responses (Kaczkurkin & Foa 2015). The treatment components of CBT for anxiety may vary between interventions but can include psychoeducation, relaxation, cognitive strategies, exposure, social skills training and problem solving (Hofmann et al. 2012).

There is a growing body of evidence that has evaluated the effectiveness of CBT in managing problemswith anxiety, anger, and depression in the ID population (Vereenooghe & Langdon 2013; Osugo & Cooper 2016). A meta-analysis of psychological therapies for children and adults with ID found CBT to be at least moderately effective in treating anger and depression with emerging evidence for anxiety (Vereenooghe & Langdon 2013). A scoping review found equivocal evidence for the effectiveness of CBT in improving anxiety for individuals with ID (Unwin et al. 2016). However, amongst these studies, few utilised standardised criteria related to a diagnosis or specific level of anxiety symptomatology and no studies were controlled studies. Nonetheless, qualitative data have shown that CBT is generally perceived as feasible and was well-tolerated amongst clients and carers (Unwin et al. 2016). A subsequent systematic review reported positive outcomes of CBT interventions on anxiety for people with ID (Dagnan et al. 2018); however, the majority of the reviewed literature consisted of single case studies. In addition, some studies included in the systematic review included participants with mixed presentations in a transdiagnostic group, whereby the effects of CBT may have been diluted due to the combination of anxious and depressed participants in treatment outcomes. Furthermore, none of the reviews have included children with an ID up until this point.

817 Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

Therefore, the existing literature investigating the effectiveness of CBT on anxiety in people with ID is ambiguous, but positive results are emerging.

There are some challenges associated with delivering CBT to the ID population. Individuals with ID may present with significant deficits in attention, learning, memory, executive function and language, all cognitive abilities required for effective CBT (Hronis et al. 2017). Hronis et al. (2017) contend that while it may be challenging to adapt CBT interventions to an individual’s unique cognitive profile, it should not preclude their participation in CBT. Moreover, there may be greater difficulties adapting CBT for certain presentations of anxiety for those with ID. For example, cognitive interventions may be more central to interventions targeting conditions such as PTSD and GAD, in comparison with specific phobia (Arch & Craske 2009) and therefore may be more difficult to adapt. Some pertinent recommendations include simplification of techniques, adjusting language, utilising activities, using directive methods, using flexible methods and involving caregivers (e.g. assign homework or rehearsals at home with the help of support persons). For children with ID, modifications include shorter sessions, engaging in implicit learning processes (e.g. role play), using visual aids and presenting information numerous times (Hronis et al. 2017).

With increased interest in anxiety interventions for the ID population over recent years and with growing insights into its potential utility and effectiveness for the ID population, a critical review of the literature on CBT treatment for anxiety in the ID group is warranted. This is pertinent considering the growing literature in the field since the previous systematic review was conducted by Dagnan et al. (2018); therefore, this study seeks to update the field of knowledge. Furthermore, this study will attempt to provide a more focused exploration of the evidence base compared with previous reviews, by applying more stringent exclusion criteria whereby only studies with interventions targeting anxiety disorders (rather than transdiagnostic groups) will be included; it is also the first systematic review to examine the effectiveness of CBT for children with anxiety and ID.

This systematic review aims to encourage awareness of the current literature around whether CBT is appropriate and effective for individuals with ID and an anxiety disorder. Moreover, it aims to

identify which adaptations to CBT and which components of CBT are currently being utilised for individuals with ID, as well as a critical analysis of the strengths and limitations and the clinical challenges within this field of research.

Materials and methods

The reporting of this systematic review was guided by the standards of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA; Moher et al. 2009; Page et al. 2021) statement. Methods of the analysis and inclusion criteria were specified in advance and documented in a protocol (registration number: CRD42020208353).

Eligibility criteria

Inclusion and exclusion criteria

Table 1 demonstrates the inclusion and exclusion criteria of this systematic review. Published studies were required to meet the following criteria: (1) to evaluate the effectiveness of CBT interventions for individuals with ID and anxiety; (2) to include participants who (a) were formally diagnosed with ID using current or older editions of any internationally recognised diagnostic criteria (e.g. Diagnostic and Statistical Manual or the International Classification of Diseases), (b) were found to demonstrate an IQ below 70 through formal cognitive testing, (c) provided previous reports from appropriate health practitioners confirming the diagnosis of ID or (d) had confirmed involvement with a community ID service provider; (3) participants were required to demonstrate anxiety through (a) a formal diagnosis using current or older editions of any recognised diagnostic criteria for anxiety, (b) report elevated levels of anxiety symptoms using a validated measure anxiety (including non-specified anxiety) or (c) demonstrate elevated anxiety that was observed through a clinical assessment or interview with a qualified health practitioner; (4) to report at least two assessment time points (e.g. baseline and post- intervention); and (5) to have been published in a peer review journal in the English language.

The current systematic review excluded studies that included a non-anxious disorder as the primary target of intervention (e.g. a mood disorder). If there was evidence that the participants experienced anxiety

818 Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

as their primary concern, comorbidities such as ASD and mood disorder such as major depressive disorder were included. Studies were excluded if the intervention did not include a specific cognitive component or if there was another non-CBT-based psychological therapy present in parallel to the intervention, whereby it would be impossible to tease apart the specific efficacy of CBT treatment on anxiety symptomology. Dissertations, book chapters, expert reviews and conference abstracts without the full text, and protocols without data were excluded. Restrictions were not placed on the age of participants in the studies included.

ID has replaced older terms, such as ‘mental retardation’, and is recognised alongside other terms such as ‘learning disability’ in the UK, and therefore, participants meeting these diagnoses were considered. Anxiety disorders that would be considered included the following: GAD; specific phobia; panic disorder; agoraphobia; social anxiety disorder; selective mutism; separation anxiety

disorder; and anxiety disorder that was induced by a substance or medication or that was due to another medical condition. OCD, acute stress disorder and PTSD were also included, as these disorders were previously considered to be anxiety disorders in previous editions of recognised diagnostic criteria.

The systematic review was limited to studies investigating CBT interventions and included studies evaluating CBT cognitive and behavioural techniques, such as cognitive restructuring; psychoeducation; behavioural activation; social skills training; relaxation; or coping skills (Cuijpers et al. 2008). In line with Dagnan et al. (2018), interventions that were considered to be a part of the wider family of CBT, such as behavioural activation or third-wave variants of CBT (e.g. mindfulness and acceptance commitment therapy), were only included if there was a specific cognitive component.

819

Table 1 The inclusion and exclusion criteria for the current systematic review

Inclusion criteria Exclusion criteria

Study topic Evaluated the effectiveness of CBT for individuals with ID and anxiety

The primary target of the intervention was a non-anxious disorder (e.g. mood disorder)

Participant Evidence of an ID through:

• Formal diagnostic assessment • Cognitive testing (IQ < 70) • Previous reports from health practitioners or, • Involvement with a community ID provider • Includes evidence for ‘mental retardation’

or a ‘learning disability’ in UK Evidence of anxiety through:

• Formal diagnostic assessment of anxiety • Elevated anxiety on a validated measure • Interview/assessment with a qualified

health practitioner Comorbidities (e.g. ASD and mood disorders) were included if anxiety was identified as the primary concern All ages

Study type/design At least two assessment time points (e.g. baseline and post-treatment)

Dissertations, book chapters, expert reviews and conference abstracts without the full text and protocolsPublished in a peer review journal in English

Intervention CBT intervention with at least a cognitive component A non-CBT based psychological therapy was also present

ASD, autism spectrum disorder; CBT, cognitive behavioural therapy; ID, intellectual disability.

Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

Information sources

The following databases were accessed: CINAHL (1937 to August 2021), EMBASE (1974 to August 2021), Medline (1946 to August 2021), PsycINFO (1806 to August 2021), Psychology and Behavioural Sciences Collection (1965 to August 2021) and Scopus (1875 to August 2021). For each database, no date limit was applied. The last search was run on 10

August 2021 by two independent researchers. Subject headings and keywords were used where available.

Search strategy

The search strategy was adapted for each specific data base. The search terms were as follows: ((learn* or intellect*) adj2 (disorder* or impair* or disab* or dysfunction*) OR mental retardation OR mental* handicap*) AND (anxi* OR phobi* OR obsessive compulsive disorder OR panic disorder OR agoraphobia OR mutism OR GAD OR OCD OR PTSDOR ((post traumatic stress or post traumatic or overanxi* or avoidan* or internali* or panic*) adj2 disorder*)) AND (cognitive behavi* therapy OR cbt OR mindfulness OR acceptance and commitment therapy OR dialectical behavi* therapy OR ACT OR MBCT OR DBT).

Study selection

In accordance with the PRISMA guidance to reporting (Moher et al. 2009; Page et al. 2021), the process for selecting studies commenced by removing duplicate articles. This was achieved using the online EndNote programme, which can automatically remove duplicates. Further duplicates were removed manually. The remaining results were screened on the basis of the title, the abstract, the participant section and other selection and exclusion criteria. The reference lists were then screened. Two independent researchers reviewed these papers in an unblinded, standardised manner. Disagreements between reviewers were resolved by a third independent reviewer.

Data collection process and synthesis of results

One researcher extracted information from each included study, utilising a pre-designed data extraction form. Information extracted from the selected studies included: aims of the study, country

of origin, participant characteristics, recruitment, intervention characteristics, medication use, study characteristics and measures, results, and quality appraisal. The results were presented and synthesised in the tables. Table 2 presents the results of pre–post intervention studies whereas Table 3 presents the results of the case studies and series. The degree of the effect sizes was interpreted utilising Ferguson’s recommendations for social science data (2009), whereby the effect sizes for r ranged from minimal (.20), moderate (.50) and strong (.80) and the effect sizes for ωp

2 ranged from minimal (.04), moderate (.25) and strong (.64). Where necessary and possible the mean and standard deviations of the outcome measures for anxiety severity were calculated.

In addition, information was collected by one researcher in relation to the treatment components of the included studies. The treatment descriptions and/or treatment manuals were examined, and the following characteristics were recorded: psychoeducation (providing didactic instruction on the nature of anxiety, information on the connection between thoughts, feelings and behaviours); relaxation strategies (diaphragmatic breathing, progressive muscle relaxation); cognitive strategies (identifying and categorising distorted automatic thoughts, cognitive restructuring, Socratic questioning, downward arrow technique, behavioural experiments); and exposure techniques (in vivo or imaginal). In addition, strategies were further specified to examine the presence of cognitive restructuring (cognitive challenging) and thought replacement, also known as self-instructional training (Willner 2005), which involves reminding oneself of coping statements. When coding the specific treatment components of each intervention, the author’s description of the purpose of the treatment component was carefully considered.

Methodological quality

The methodological quality of each study was appraised using established quality assessment tools by the National Institutes of Health (NIH). The NIH has developed a set of quality assessment tools that are tailored to various study designs, such as before-and- after (pre–post) studies with no control group (National Institutes of Health 2014a) and case series designs (National Institutes of Health 2014b). The

820 Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

821

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so ci al an xi et y an d O C D

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an xi et y fo r ch ild re n,

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M ai n fi nd

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lq ua

lit y‡

Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

822

T ab

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2 p = .4 5 ),

SC A R ED

-P (ω

2 p = .1 4 ) an d FS SC

-R (n

= 1 6 ;ω

2 p = .2 0 )] .

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so ci al av oi da nc e

(ω 2 p = .5 0 ), ob

se ss iv e–

co m pu ls iv e

sy m pt om

s (ω

2 p = .1 8 ), de pr es si on

(ω 2 p = .2 3 ), an d m oo

d sy m pt om

s (ω

2 p = .2 0 ) w er e ob

se rv ed

on th e

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th e

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Fa ir

Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

quality assessment tool for case series designs was also applied to case reports, as there were limited tools available for this study design and because the tool captured important aspects to assess which are relevant to case studies. These tools were selected as they assessed the internal validity and risk of bias in a similar manner. The quality assessments were undertaken by two independent researchers. Any disagreements (N = 16, and 15%) were resolved through discussions with a third party (co-author, M. P.) and were re-coded by the independent third party (co-author, M. P.). These tools informed the reviewers’ critical appraisal of the studies and their classification of the studies as ‘good’, ‘fair’ or ‘poor’. Results of the overall quality assessments are reported in Tables 2 and 3.

Results

Study selection

Figure 1 presents the flowchart describing the inclusion and exclusion of studies.

Study characteristics

Five of the nine included studies were uncontrolled before and after (pre–post) studies, two were case studies and two were case series. Tables 2–6 show the characteristics of studies across various groups of participants.

Participants

The selected studies included a total of 60 participants, aged between 12 and 73 years. The majority of studies included individuals with a mild ID (Marwood & Hewitt 2013; Stuart et al. 2014; Carrigan & Allez 2017; Roberts & Kwan 2018; Giannaki & Hewitt 2021). Four studies included participants with borderline or moderate ID (Lindsay et al. 1997; Douglass et al. 2007; Phillips & Klein- Tasman 2009; Roberts & Kwan 2018). One study did not specify the participants’ level of ID but reported a range of intellectual functioning for participants (IQ = 40–79; Blakeley-Smith et al. 2021). ID was confirmed by a written report from a qualified clinician (Roberts & Kwan 2018), by formally testing IQ and adaptive functioning (Lindsay et al. 1997; Phillips & Klein-Tasman 2009; Stuart et al. 2014;

823

†

T he

ou tc om

e m ea su re s pr ov id e ba se lin e an d po

st -t re at m en t da ta .

‡

T he

m et ho

do lo gi ca lq ua lit y of

st ud ie s w as

as se ss ed

us in g th e N IH

Q ua lit y A ss es sm

en tT

oo lf or

Be fo re -A fte

r (P re -P os t) St ud ie s W

ith N o C on

tr ol

G ro up .1 .C

le ar

ob je ct iv es

= W

as th e st ud y qu es tio

n or

ob je ct iv e

cl ea rl y st at ed ?; 2.

C le ar

el ig ib ili ty

cr ite

ri a = W

er e el ig ib ili ty /s el ec tio

n cr ite

ri a fo r th e st ud y po

pu la tio

n pr es pe ci fi ed

an d cl ea rl y de sc ri be d? ;3

.R ep re se nt at iv e pa rt ic ip an ts

= W

er e th e pa rt ic ip an ts

in th e st ud y re p-

re se nt at iv e of

th os e w ho

w ou

ld be

el ig ib le fo r th e te st /s er vi ce /in te rv en tio

n in th e ge ne ra lo

r cl in ic al po

pu la tio

n of

in te re st ?; 4. A ll el ig ib le pe rs on

s en ro lle d = W

er e al le lig ib le pa rt ic ip an ts th at

m et

th e pr es pe ci fi ed

en tr y cr ite

ri a en ro lle d? ;5

.S uf fi ci en t sa m pl e si ze

= W

as th e sa m pl e si ze

su ffi ci en tly

la rg e to

pr ov id e co nfi de nc e in

th e fi nd in gs ?; 6.

In te rv en tio

n = W

as th e te st /s er vi ce /in te rv en tio

n cl ea rl y de sc ri be d an d de liv er ed

co ns is te nt ly ac ro ss

th e st ud y po

pu la tio

n? ;7

= O M

de fi ne d,

va lid ,r el ia bl e = W

er e th e ou

tc om

e m ea su re s pr es pe ci fi ed ,c le ar ly de fi ne d,

va lid ,r el ia bl e, an d as se ss ed

co ns is te nt ly ac ro ss

al ls tu dy

pa rt ic ip an ts ?; 8.

A ss es so r bl in di ng

= W

er e th e pe op

le as se ss in g th e ou

tc om

es bl in de d to

th e pa rt ic ip an ts ’e xp os ur es /in te rv en tio

ns ?; 9. Fo

llo w -u p 20 % or

le ss ?=

W as

th e lo ss to

fo llo w -u p af te r ba se lin e 20 % or

le ss ?W

er e th os e lo st

to fo llo w -u p ac co un te d fo r in th e an al ys is ?; 10 .S ta tis tic al an al ys is = D id th e st at is tic al m et ho

ds ex am

in e ch an ge s in ou

tc om

e m ea su re s fr om

be fo re

to af te r th e in te rv en tio

n? W

er e st at is tic al te st s do

ne th at pr ov id ed

p va lu es

fo r th e pr e- to -p os t ch an ge s? ;1

1. M ul tip

le O M

= W

er e ou

tc om

e m ea su re s of

in te re st

ta ke n m ul tip

le tim

es be fo re

th e in te rv en tio

n an d m ul tip

le tim

es af te r th e in te rv en tio

n (…

)? ;1

2. In di vi du al -le

ve l

ou tc om

e fo r gr ou

p- le ve li nt en tio

n = If th e in te rv en tio

n w as

co nd uc te d at

a gr ou

p le ve l( …

) di d th e st at is tic al an al ys is ta ke

in to

ac co un t th e us e of

in di vi du al -le

ve ld

at a to

de te rm

in e ef fe ct s at

th e gr ou

p le ve l?

N ot e: A BC

-C ,A

be rr an t Be

ha vi ou

r C he ck lis t- C om

m un ity

(A m an

et al .1

99 5) ;A

D A M S, A nx ie ty

D ep re ss io n an d M oo

d Sc al e (E sb en se n et

al .2

00 3) ;A

D IS -IV

,A nx ie ty

D is or de rs

In te rv ie w

Sc he du le fo r D SM

-IV ,

pa re nt

ve rs io n (S ilv er m an

& A lb an o 19 96

); BA

I-Y ,B

ec k A nx ie ty

In ve nt or y Y ou

th (B ec k et

al .2

00 1) ;C

BC L,

C hi ld

Be ha vi ou

r C he ck lis t (A ch en ba ch

& R es co rl a 20 01

); FS SC

-R ,F ea r Su rv ey

Sc he du le fo r

C hi ld re n- R ev is ed

(O lle nd ic k 19 83

); M A SC

,M ul tid

im en si on

al A nx ie ty

Sc al e fo r C hi ld re n (M

ar ch

19 97

); R C M A S, R ev is ed

C hi ld re n’ s M an ife st A nx ie ty

Sc al e (R ey no

ld s & R ic hm

on d 19 98

); SC

A R E- P, Sc re en

fo r C hi ld

A nx ie ty

R el at ed

D is or de rs ,P

ar en t V er si on

(B ir m ah er

et al .1

99 9) .

A D H D ,a tt en tio

n- de fi ci t/ hy pe ra ct iv ity

di so rd er ;B

L, ba se lin e; C BT

,c og ni tiv e be ha vi ou

ra lt he ra py ;C

D ,c an no

t de te rm

in e; M ,g ro up

m ea n; N ,n o;

N ,n um

be r of

pa rt ic ip an ts ;N

/A ,n ot

ap pl ic ab le ;N

R ,n ot

re po

rt ed ;

O D D ,o

pp os iti on

al de fi an t di so rd er ;O

M ,o

ut co m e m ea su re ;P

T ,p

os t- tr ea tm

en t; SD

,s ta nd ar d de vi at io n;

si g, si gn ifi ca nt ;s ig ,s ig ni fi ca nt ;Y

,y es .

Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

824

T ab

le 3

S ys te m at ic

re vi ew

su m m ar y of

fi n d in gs

fo r C B T

fo r ad

u lt s w it h ge n er al is ed

an xi et y or

m ix ed

an xi et y (n

= 4 )

R ef er en

ce an

d co

un tr y

St ud

y/ sa m pl in g ch

ar ac

te ri st ic s

A nx

ie ty

co nd

it io ns

In te rv en

ti on

de si gn

an d de

ta ils

M ea

su re s us ed

D ou

gl as s et

al .( 20 07 )

U K

• N = 6 (4

fe m al es ), 2 2 – 6 5 ye ar s ol d

• 1 pa rt ic ip an t dr op

pe d ou

t be fo re

th e be gi nn in g of

th e gr ou

p •

Bo rd er lin e- m od

er at e ID

• Pr e- po

st st ud y

• G en er al is ed

an xi et y

sy m pt om

s •

Pr e & po

st in te rv en tio

n no

co nt ro l,

m ix ed

m et ho

d de sig n

• C BT

w ith

th e as sis ta nc e

of a su pp or t pe rs on

• 1 2 × 1 2 0 m in

se ss io ns

ov er

1 2 w ee ks

• G ro up

th er ap y, fa ce -t o- fa ce

in th e co m m un ity

• C lin ic ia ns :A

ss is ta nt

Ps yc ho

lo gi st ,

T ra in ee

C lin ic al

Ps yc ho

lo gi st ,L

ea rn in g

D is ab ili ty

N ur se

an d

O cc up at io na lT

he ra pi st T ec hn ic ia n

• G A S- ID ,a

se lf- re po

rt m ea su re

of an xi et y

(G ia nn ak i&

H ew

itt 20 21 )

U K

• N = 4 (3

fe m al es ), ag ed

2 1 – 5 5 ye ar s of

ag e

• M ild

ID •

Pa rt ic ip an ts w er e

re fe rr ed

to th e ps yc ho

lo gy

se rv ic e fo r pe op

le w ith

a le ar ni ng

di sa bi lit y

• Pr e- po

st st ud y

• Sy m pt om

s re la te d

to ge ne ra lis ed

an xi et y an d

sp ec ifi c ph ob

ia

• Pr e & po

st in te rv en tio

n no

co nt ro l

• Fo

llo w -u p at

4 m on

th s

• C BT

w ith

th e as sis ta nc e

of a su pp or t pe rs on

• C BT

co nc ep ts w er e

ba se d on

Be ck

(1 9 7 9 )

• 7 w ee kl y se ss io ns

(d id

no t re po

rt on

th e

du ra tio

n of

se ss io ns )

• G ro up

th er ap y, fa ce -t o- fa ce

in th e co m m un ity

• C lin ic ia ns :t ra in ee

cl in ic al ps yc ho

lo gi st s

an d as si st an t ps yc ho

lo gi st s

• G A S- ID

se lf- re po

rt •

H oN

O S- LD

,a se lf- re po

rt m ea su re

of gl ob

al fu nc tio

ni ng .

• PT

O S- ID ,s el f-

an d su pp or te r-

re po

rt m ea su re

of ps yc ho

lo gi ca ld

is tr es s

an d w el lb ei ng .

M ar w oo

d an d H ew

itt (2 01 3)

U K

• N = 8 (4

fe m al es ), ag ed

1 7 – 7 3 ye ar s of

ag e

• M ild

ID •

Pa rt ic ip an ts w er e re cr ui te d

th ro ug h N H S

re fe rr al s to

th e ps yc ho

lo gi ca l

se rv ic e fo r

pe op

le w ith

a le ar ni ng

di sa bi lit y

• In cl ud ed

pa rt ic ip an ts w ith

au tis m

an d de pr es si on

. •

Pr e- po

st st ud y

• In cl ud ed

sy m pt om

s of

sp ec ifi c ph ob

ia ,

so ci al an xi et y,

ge ne ra lis ed

an xi et y,

an d ob

se ss io na la nx ie ty .

• Pr e & po

st in te rv en tio

n no

co nt ro l,

m ix ed

m et ho

d de sig n

• C BT

th er ap y w ith

th e as si st an ce

of a su pp or t pe rs on

• 6 × 6 0 m in

se ss io ns

ov er

6 w ee ks

• G ro up

th er ap y, fa ce -t o- fa ce

in th e co m m un ity

• C lin ic ia ns :t ra in ee

ps yc ho

lo gi st an d

an as si st an t ps yc ho

lo gi st

• G A S- ID

se lf- re po

rt •

Q oL

• H oN

O S– LD

Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

825

T ab

le 3.

(C on tin

ue d)

R ef er en

ce an

d co

un tr y

St ud

y/ sa m pl in g ch

ar ac

te ri st ic s

A nx

ie ty

co nd

it io ns

In te rv en

ti on

de si gn

an d de

ta ils

M ea

su re s us ed

R ob

er ts & K w an

(2 01 8)

A U S

• N = 1 3 (7

fe m al es ), ag ed

1 8 – 5 5 ye ar s of

ag e

• M ild

(n = 1 0 ) an d m od

er at e

(n = 3 ) ID

• Pa rt ic ip an ts w er e re cr ui te d

th ro ug h ad ve rt is em

en ts

to se rv ic es

an d gr ou

ps fo r

pe op

le w ith

ID (e .g .r es pi te

se rv ic es ,

m en ta lh

ea lth

se rv ic es )

• Pr e- po

st st ud y

• D ia gn os es

of sp ec ifi c

ph ob

ia ,s oc ia l

ph ob

ia an d

ge ne ra lis ed

an xi et y di so rd er

• Pr e & po

st in te rv en tio

n no

co nt ro l

• C BT

gr ou

p th er ap y w ith

op tio

na l

as si st an ce

of a th er ap y pa rt ne r

• 6 × 9 0 m in

se ss io ns

ov er

6 w ee ks

• G ro up

th er ap y, fa ce -t o- fa ce

• T he

th er ap y m at er ia ls

w er e cr ea te d by

a re gi st er ed

cl in ic al ps yc ho

lo gi st ,

th e fi rs t au th or

an d w er e ba se d

on C BT

pr og ra m m es

fo r

ty pi ca lly

de ve lo pi ng

in di vi du al s w ith

an xi et y

• G A S- ID

co m pl et ed

by th e

pa rt ic ip an ts an d th ei r ca re r

or su pp or t w or ke r

• PA

S- A D D ,a

cl in ic al in te rv ie w ,

w as

ad m in ist er ed

by a cl in ic al ps yc ho

lo gi st to

di ag no

se an xi et y di so rd er s

• M in iP

A S- A D D

w as

ad m in ist er ed

by a cl in ic al nu rs e

co ns ul ta nt

to sc re en

fo r

an xi et y di so rd er s

R ef er en

ce an

d co

un tr y

M ai n fi nd

in gs

† L im

it at io ns

M et ho

do lo gi ca

lq ua

lit y‡

D ou

gl as s et

al .( 20 07 )

U K

• H al ft he

pa rt ic ip an ts re po

rt ed

im pr ov em

en ts

in an xi et y sc or es

at PT

• Si g lo w er

se lf- re po

rt ed

an xi et y (G

A S- ID )

or 2 pa rt ic ip an ts

• Sl ig ht

in cr ea se s in

se lf- re po

rt ed

an xi et y

(G A S- ID ) fo r 3 pa rt ic ip an ts

• A ll pa rt ic ip an ts re po

rt ed

le ar ni ng

ne w

w ay s

of co pi ng

w ith

th ei r an xi et y at

PT •

N o at tr iti on

• G ro up

m ea n of

an xi et y

re du ce d fr om

BL (M

= 2 5 .5 0 ,S D = 3 .0 4 ) to

PT (M

= 2 1 .8 3 ,S D = 7 .3 8 )§

• D id

no t ad eq ua te ly de sc ri be

th e in te rv en tio

n •

D id

no t ve ri fy th e ID

of al lp

ar tic ip an ts ,l ev el s

of ID

w er e de te rm

in ed

by cl in ic al ju dg em

en t

• A nx ie ty

di so rd er

w as

no t

fo rm

al ly di ag no

se d

• N o fo llo w -u p da ta

• La ck

of m ul tip

le -b as el in es

1. C le ar

ob je ct iv es

2. C le ar

el ig ib ili ty

cr ite

ri a

3. R ep re se nt at iv e pa rt ic ip an ts

4. A ll el ig ib le pe rs on

s en ro lle d

5. Su ffi ci en t sa m pl e si ze

6. In te rv en tio

n 7.

O M

de fi ne d,

va lid ,r el ia bl e

8. A ss es so r bl in di ng

9. Fo

llo w -u p 20 % or

le ss ?

10 .S ta tis tic al an al ys is

11 .M

ul tip

le O M

12 .I nd iv id ua l-l ev el ou

tc om

e fo r gr ou

p- le ve li nt en tio

ns Q ua lit y ra tin

g:

Y Y Y Y N N Y N Y N N N /A

Po or

Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

826

T ab

le 3.

(C on tin

ue d)

R ef er en

ce an

d co

un tr y

M ai n fi nd

in gs

† L im

it at io ns

M et ho

do lo gi ca

lq ua

lit y‡

(G ia nn ak i&

H ew

itt 20 21 )

U K

• A ll fo ur

pa rt ic ip an ts ex pe ri en ce d

si g re du ct io ns

in an xi et y fr om

BL to

PT (P

< .0 5 );

th es e ga in s re m ai ne d la rg el y

at fo llo w -u p.

• T he

gr ou

p m ea n fo r

an xi et y re du ce d fr om

BL (M

= 2 5 .3 ,S D = 5 .9 0 ) to

PT (M

= 1 3 ,S D = 3 .8 2 ).

• T he

ov er al ll ev el of

di st re ss

w as

re du ce d w he re as

th e ov er al ll ev el of

gl ob

al fu nc tio

ni ng

in th e gr ou

p w as

en ha nc ed

in th e gr ou

p at

PT co m pa re d w ith

BL .

• N o at tr iti on

.

• Sm

al ls am

pl e si ze ,n

o co nt ro l

gr ou

p, th er eb y re du ci ng

th e

re lia bi lit y an d ge ne ra lis ab ili ty

of th e st ud y

• N o fo rm

al di ag no

si s of

an xi et y

re qu ir ed

fo r pa rt ic ip at io n

• La ck

of co ns is te nc y in

th e

pr oc ed ur es

(e .g .o

ne pa rt ic ip an t

jo in ed

th e gr ou

p in

th e fo ur th

w ee k)

1. C le ar

ob je ct iv es

2. C le ar

el ig ib ili ty

cr ite

ri a

3. R ep re se nt at iv e pa rt ic ip an ts

4. A ll el ig ib le pe rs on

s en ro lle d

5. Su ffi ci en t sa m pl e si ze

6. In te rv en tio

n 7.

O M

de fi ne d,

va lid ,r el ia bl e

8. A ss es so r bl in di ng

9. Fo

llo w -u p 20 % or

le ss ?

10 .S ta tis tic al an al ys is

11 .M

ul tip

le O M

12 .I nd iv id ua l-l ev el ou

tc om

e fo r gr ou

p- le ve li nt en tio

ns Q ua lit y ra tin

g:

Y Y Y N R

N C D

Y N Y Y N N /A

Fa ir

M ar w oo

d an d H ew

itt (2 01 3)

U K

• Si g re du ct io n in

se lf- re po

rt ed

an xi et y

(G A S- ID ) fo r 2 pa rt ic ip an ts .

• Im

pr ov em

en ts in

th e gr ou

p m ea ns

in an xi et y fr om

BL (M

= 2 6 .8 8 ,S D = 7 .2 5 ) to

PT (M

= 2 3 .3 8 ,S D = 7 .4 2 )§ .

• Im

pr ov em

en ts in

gr ou

p m ea ns

in gl ob

al fu nc tio

ni ng

an d qu al ity

of lif e w er e

ob se rv ed

fr om

BL to

PT .

• So m e pa rt ic ip an ts

ha d co m or bi di tie

s (a ut is m

sp ec tr um

di so rd er

an d de pr es si on

) •

C lin ic al cu t- of fs fo r an xi et y w er e no

t pr ed et er m in ed

fo r el ig ib ili ty

• Sm

al ls am

pl e si ze ,

po te nt ia lly

lim iti ng

th e

ge ne ra lis ab ili ty

of th e st ud y

• N o fo llo w -u p da ta

1. C le ar

ob je ct iv es

2. C le ar

el ig ib ili ty

cr ite

ri a

3. R ep re se nt at iv e pa rt ic ip an ts

4. A ll el ig ib le pe rs on

s en ro lle d

5. Su ffi ci en t sa m pl e si ze

6. In te rv en tio

n 7.

O M

de fi ne d,

va lid ,r el ia bl e

8. A ss es so r bl in di ng

9. Fo

llo w -u p 20 % or

le ss ?

10 .S ta tis tic al an al ys is

11 .M

ul tip

le O M

12 .I nd iv id ua l-l ev el ou

tc om

e fo r gr ou

p- le ve li nt en tio

ns Q ua lit y ra tin

g:

Y N Y C D

N Y Y N Y N N N /A

Po or

R ob

er ts & K w an

(2 01 8)

A U S

• Si g re du ct io n in

th e pr op

or tio

n of

pa rt ic ip an ts di ag no

se d

as cl in ic al ly an xi ou

s fr om

BL to

PT (7 6 .9 % – 7 .7 % ).

• N o fo llo w -u p ou

tc om

e da ta

• A si ng le cl in ic al ad m in ist er ed

th e

cl in ic al as se ss m en ts at

BL an d PT

w ho

w as

no t

bl in de d to

th e co nd iti on

s

1. C le ar

ob je ct iv es

2. C le ar

el ig ib ili ty

cr ite

ri a

3. R ep re se nt at iv e pa rt ic ip an ts

4. A ll el ig ib le pe rs on

s en ro lle d

5. Su ffi ci en t sa m pl e si ze

Y Y Y N R

N

Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

827

T ab

le 3.

(C on tin

ue d)

R ef er en

ce an

d co

un tr y

M ai n fi nd

in gs

† L im

it at io ns

M et ho

do lo gi ca

lq ua

lit y‡

• 1 1 pa rt ic ip an ts no

lo ng er

m et

cr ite

ri a fo r th ei r pr im ar y

an xi et y di ag no

si s at

PT .

• Si g re du ct io ns

in an xi et y

(G A S- ID ) w er e fo un d

fo r se lf- re po

rt (z

= �3

.0 6 ,

P <

.0 1 ) an d

in fo rm

an t- re po

rt (z

= �2

.4 9 ,

P = .0 1 ) fo llo w in g

th e in te rv en tio

n. Bo

th th e

ef fe ct

si ze s w er e m od

er at e

(r = .6 0 fo r se lf- ra tin

g an d r = .4 9

fo r in fo rm

an t ra tin

gs ).

• La ck

of m ul tip

le ba se lin es

an d a co nt ro lg ro up

6. In te rv en tio

n 7.

O M

de fi ne d,

va lid ,r el ia bl e

8. A ss es so r bl in di ng

9. Fo

llo w -u p 20 % or

le ss ?

10 .S ta tis tic al an al ys is

11 .M

ul tip

le O M

12 .I nd iv id ua l-l ev el ou

tc om

e fo r gr ou

p- le ve li nt en tio

ns Q ua lit y ra tin

g:

Y Y N N R

Y N N /A

Fa ir

†

T he

ou tc om

e m ea su re s pr ov id e ba se lin e an d po

st -t re at m en t da ta .

‡

T he

m et ho

do lo gi ca lq

ua lit y of

st ud ie s w as

as se ss ed

us in g th e N IH

Q ua lit y A ss es sm

en t T oo

lf or

Be fo re -A fte

r (P re -P os t) St ud ie s W

ith N o C on

tr ol

G ro up .1

.C le ar

ob je ct iv es

= 1.

W as

th e st ud y qu es tio

n or

ob je ct iv e cl ea rl y st at ed ?; 2.

C le ar

el ig ib ili ty

cr ite

ri a = W

er e el ig ib ili ty /s el ec tio

n cr ite

ri a fo r th e st ud y po

pu la tio

n pr es pe ci fi ed

an d cl ea rl y de sc ri be d? ;3

.R ep re se nt at iv e pa rt ic ip an ts

= W

er e th e pa rt ic ip an ts

in th e

st ud y re pr es en ta tiv e of

th os e w ho

w ou

ld be

el ig ib le fo r th e te st /s er vi ce /in te rv en tio

n in

th e ge ne ra lo

r cl in ic al po

pu la tio

n of

in te re st ?; 4.

A ll el ig ib le pe rs on

s en ro lle d = W

er e al le lig ib le pa rt ic ip an ts

th at

m et

th e

pr es pe ci fi ed

en tr y cr ite

ri a en ro lle d? ;5 .S uf fi ci en ts am

pl e si ze

= W

as th e sa m pl e si ze

su ffi ci en tly

la rg e to

pr ov id e co nfi de nc e in th e fi nd in gs ?; 6. In te rv en tio

n = W

as th e te st /s er vi ce /in te rv en tio

n cl ea rl y de sc ri be d an d

de liv er ed

co ns is te nt ly ac ro ss th e st ud y po

pu la tio

n? ;7

= O M

de fi ne d, va lid ,r el ia bl e = W

er e th e ou

tc om

e m ea su re s pr es pe ci fi ed ,c le ar ly de fi ne d, va lid ,r el ia bl e, an d as se ss ed

co ns is te nt ly ac ro ss al ls tu dy

pa rt ic ip an ts ?;

8. A ss es so r bl in di ng

= W

er e th e pe op

le as se ss in g th e ou

tc om

es bl in de d to

th e pa rt ic ip an ts ’e xp os ur es /in te rv en tio

ns ?; 9. Fo

llo w -u p 20 % or

le ss ?=

W as

th e lo ss to

fo llo w -u p af te r ba se lin e 20 % or

le ss ?W

er e th os e

lo st to

fo llo w -u p ac co un te d fo r in

th e an al ys is ?; 10 .S ta tis tic al an al ys is = D id th e st at is tic al m et ho

ds ex am

in e ch an ge s in

ou tc om

e m ea su re s fr om

be fo re

to af te r th e in te rv en tio

n? W

er e st at is tic al te st s do

ne th at

pr ov id ed

p va lu es

fo r th e pr e- to -p os t ch an ge s? ;1

1. M ul tip

le O M

= W

er e ou

tc om

e m ea su re s of

in te re st

ta ke n m ul tip

le tim

es be fo re

th e in te rv en tio

n an d m ul tip

le tim

es af te r th e in te rv en tio

n (…

)? ;1

2. In di vi du al -le

ve lo

ut co m e fo r gr ou

p- le ve li nt en tio

n = If th e in te rv en tio

n w as

co nd uc te d at

a gr ou

p le ve l( … ) di d th e st at is tic al an al ys is ta ke

in to

ac co un t th e us e of

in di vi du al -le

ve ld

at a to

de te rm

in e ef fe ct s at

th e

gr ou

p le ve l?

§ A n es tim

at e w as

ca lc ul at ed

fo r th e gr ou

p m ea n an d st an da rd

de vi at io n.

N ot e: G A S- ID ,G

la sg ow

A nx ie ty

Sc al e fo r pe op

le w ith

an In te lle ct ua lD

is ab ili ty (M

in dh am

& Es pi e 20 03

); H oN

O S- LD

,H ea lth

of th e N at io n Br ie fO

ut co m e M ea su re

fo r Pe op

le w ith

Le ar ni ng

D is ab ili tie

s an d M en ta l

H ea lth

N ee ds

(R oy

et al .2

00 2) ;P

A S- A D D ,P

sy ch ia tr ic A ss es sm

en t Sc he du le

fo r A du lts

w ith

D ev el op

m en ta lD

is ab ili tie

s (M

os s & Fr ie dl an de r 20 11

); Q oL

,Q ua lit y of

Li fe

Sc al e (A nd re w s & W

ith ey

19 76

). A U S, A us tr al ia ;B

L, ba se lin e; C BT

,c og ni tiv e be ha vi ou

ra lt he ra py ;C

D ,c an no

td et er m in e; M ,g ro up

m ea n; N ,n o; N ,n um

be r of

pa rt ic ip an ts ;N

/A ,n ot

ap pl ic ab le ;N

R ,n ot

re po

rt ed ;O

M ,o ut co m e m ea su re ;P T ,p os t-

tr ea tm

en t; SD

,s ta nd ar d de vi at io n;

si g, si gn ifi ca nt ;s ig ,s ig ni fi ca nt ;U

K ,U

ni te d K in gd om

;Y ,y es .

Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

Blakeley-Smith et al. 2021), or through health records (Marwood & Hewitt 2013). Douglass et al. (2007) reported that the ID of clients was largely determined based on the clinical judgement of the researchers. Giannaki and Hewitt (2021) and Carrigan and Allez (2017) did not clarify how the participants’ level

of ID was determined or verified; however, these participants had confirmed involvement with a community ID service provider. Overall, the majority of participants were recruited by convenience or were referred by professionals to a private service.

828

FIGURE 1. PRISMA 2009 flow diagram highlights the exclusion of articles at each search stage

Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

829

T ab

le 4

S ys te m at ic

re vi ew

su m m ar y of

fi n d in gs

fo r C B T

fo r ad

u lt s w it h P T S D

sy m pt om

s (n

= 1 )

R ef er en

ce an

d co

un tr y

St ud

y/ sa m pl in g ch

ar ac

te ri st ic s

A nx

ie ty

co nd

it io ns

In te rv en

ti on

de si gn

an d de

ta ils

M ea

su re s us ed

C ar ri ga n an d A lle z (2 01 7)

U K

• N = 1 m al e, 2 6 ye ar s ol d

• M ild

ID an d A SD

• C as e st ud y

• PT

SD sy m pt om

s •

C as e st ud y

• T ra um

a- fo cu se d C BT

w ith

el em

en ts of

co gn iti ve

th er ap y

ba se d on

th e ap pr oa ch

by (E hl er s et

al .2

0 0 5 )

• 1 2 × 6 0 m in

se ss io ns

ov er

1 2 w ee ks

• In di vi du al se ss io ns ,f ac e- to

fa ce

in th e co m m un ity

• C lin ic ia n w as

a cl in ic al ps yc ho

lo gi st

• C R IE S- 8 w hi ch

is a

se lf- re po

rt m ea su re

of in tr us io ns

an d av oi da nc e

R ef er en

ce an

d co

un tr y

M ai n fi nd

in gs

† L im

it at io ns

M et ho

do lo gi ca

lq ua

lit y‡

C ar ri ga n an d A lle z (2 01 7)

U K

• T he

C R IE S- 8 sc or e

re du ce d fr om

3 2 to

1 1 ,

w hi ch

w as

be lo w

th e

cl in ic al cu t of fo

f1 7 (Y ul e 1 9 9 2 ).

• Pa rt ic ip an t an d hi s

pa re nt

re po

rt ed

im pr ov em

en ts in

PT SD

sy m pt om

s.

• N o fo rm

al di ag no

si s of

ID ,

un cl ea r w he th er

do cu m en ta tio

n w as

si gh te d to

co nfi rm

di ag no

si s

• A br ie fs cr ee ni ng

to ol

de ve lo pe d fo r th e ge ne ra l

po pu la tio

n w as

us ed

to as se ss

PT SD

sy m pt om

s, an d th er ef or e m ay

be su bj ec t

to m ea su re m en t er ro r

• La ck

of m ul tip

le ba se lin es

• N o fo llo w -u p da ta

1. C le ar

st ud y qu es tio

n 2.

C le ar

ca se

de fi ni tio

n 3.

C on

se cu tiv e ca se s

4. C om

pa ra bl e su bj ec ts

5. C le ar

in te rv en tio

n 6.

O M

de fi ne d,

va lid

& re lia bl e

7. A de qu at e fo llo w -u p le ng th

8. St at is tic al m et ho

ds w el l-d

es cr ib ed

9. R es ul ts w el l-d

es cr ib ed

Q ua lit y ra tin

g:

Y Y N /A

N /A Y N Y N /A Y

Po or

†

T he

ou tc om

e m ea su re s pr ov id e ba se lin e an d po

st -t re at m en t da ta .

‡

T he

m et ho

do lo gi ca lq

ua lit y of

st ud ie s w as

as se ss ed

us in g th e N IH

Q ua lit y A ss es sm

en t of

C as e Se ri es

St ud ie s. 1.

C le ar

st ud y qu es tio

n = W

as th e st ud y qu es tio

n or

ob je ct iv e cl ea rl y st at ed ?; 2.

C le ar

ca se

de fi ni tio

n = W

as th e st ud y po

pu la tio

n cl ea rl y an d fu lly

de sc ri be d, in cl ud in g a ca se

de fi ni tio

n? ;3 .C

on se cu tiv e ca se s = W

er e th e ca se s co ns ec ut iv e? ;4 .C

om pa ra bl e su bj ec ts = W

er e th e su bj ec ts co m pa ra bl e? ;5 .C

le ar

in te rv en tio

n = W

as th e in te rv en tio

n cl ea rl y de sc ri be d? ;6 .O

M de fi ne d, va lid

& re lia bl e = W

er e th e ou

tc om

e m ea su re s cl ea rl y de fi ne d, va lid ,r el ia bl e, an d im pl em

en te d co ns is te nt ly ac ro ss

al ls tu dy

pa rt ic ip an ts ?; 7.

A de qu at e fo llo w -u p le ng th

= W

as th e le ng th

of fo llo w -u p ad eq ua te ?; 8.

St at is tic al m et ho

ds w el l-d

es cr ib ed

= W

er e th e st at is tic al m et ho

ds w el l-d

es cr ib ed ?; 9.

R es ul ts

w el l-d

es cr ib ed

= W

er e th e re su lts

w el l-

de sc ri be d?

N ot e: C R IE S- 8,

R ev is ed

C hi ld

Im pa ct

of Ev en ts

Sc al e (S m ith

et al .2

00 3) .

BL ,b as el in e; C BT

,c og ni tiv e be ha vi ou

ra lt he ra py ;C

D ,c an no

td et er m in e; M ,g ro up

m ea n; m in ,m

in ut es ;N

,n o;

N ,n um

be r of

pa rt ic ip an ts ;N

/A ,n ot

ap pl ic ab le ;N

R ,n ot

re po

rt ed ;O

M ,o

ut co m e m ea su re ;P T ,p os t-

tr ea tm

en t; SD

,s ta nd ar d de vi at io n;

si g, si gn ifi ca nt ;s ig ,s ig ni fi ca nt ;U

K ,U

ni te d K in gd om

;Y ,y es .

Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

830

T ab

le 5

S ys te m at ic

re vi ew

su m m ar y of

fi n d in gs

fo r C B T

fo r ad

u lt s w it h n on

-s pe

ci fi ed

an xi et y (n

= 2 )

R ef er en

ce an

d co

un tr y

St ud

y/ sa m pl in g ch

ar ac

te ri st ic s

A nx

ie ty

co nd

it io ns

In te rv en

ti on

de si gn

an d de

ta ils

M ea

su re s us ed

Li nd sa y et

al .( 19 97 )

U K

• N = 2 ,1 9 an d 2 7 ye ar -o ld

m al es

• M ild

in te lle ct ua ld

is ab ili ty

(IQ = 6 6 – 6 7 )

• El ev at ed

le ve ls of

de pr es si on

fo r 1 pa rt ic ip an t

• N on

-s pe ci fi ed

an xi et y

(e le va te d le ve ls of

an xi et y)

• C as e se ri es

• In di vi du al co gn iti ve

fo r an xi et y

fo r ad ul ts ,b

as ed

up on

Be ck

et al .’s

(1 9 7 9 ) m an ua l

• Pa rt ic ip an t 1 :4

1 in di vi du al

se ss io ns

ov er

1 -y ea r ta rg et ed

an xi et y

• Pa rt ic ip an t 2 :1 4 se ss io ns

ov er

1 4 w ee ks

• Fo

llo w -u p at

3 - an d 6 -m

on th s PT

fo r ea ch

pa rt ic ip an t re sp ec tiv el y

• BA

I, a se lf- re po

rt m ea su re

of an xi et y.

• BD

I, a se lf- re po

rt m ea su re

of de pr es si on

.

St ua rt

et al .( 20 14 )

U K

• N = 1 fe m al e, 4 0 ye ar s ol d

• M ild

ID •

A nx io us

an d de pr es si ve

sy m pt om

s •

Pa rt ic ip an t w as

re fe rr ed

fr om

th ei r G P to

th e C LD

T

• N on

-s pe ci fi ed

an xi et y

• C as e st ud y

• Be

ha vi ou

ra lly

fo cu se d in di vi du al C BT

• 7 se ss io ns

ov er

1 2 w ee ks

(t he

du ra tio

n of

se ss io ns

w as

no t re po

rt ed )

• G A S- ID

se lf- re po

rt m ea su re

an xi et y

• G D S- LD

,s el f-r ep or t

m ea su re

of de pr es si on

R ef er en

ce an

d co

un tr y

M ai n fi nd

in gs

† L im

it at io ns

M et ho

do lo gi ca

lq ua

lit y‡

Li nd sa y et

al .( 19 97 )

U K

• Si g re du ct io ns

in an xi et y fo r bo

th pa rt ic ip an ts ;t he ir BA

Is co re

re du ce d

fr om

ve ry

hi gh

le ve ls at

BL to

to le ra bl e

or no

rm al le ve ls at

PT .G

ai ns

w er e

m ai nt ai ne d at

fo llo w -u p (3 – 6 m on

th s

af te r PT

). •

A si g re du ct io n in

an xi et y- re la te d

co gn iti on

s w as

ob se rv ed .

• A si g im pr ov em

en t in

de pr es si on

se ve ri ty

w as

al so

ob se rv ed

fo r on

e pa rt ic ip an t.

• N o fo rm

al di ag no

si s of

an xi et y

• D id

no t re po

rt on

th e le ve lo

fI D

• D id

no t re po

rt on

th e le ve lo

f tr ai ni ng

of th e fa ci lit at or s

1. C le ar

st ud y qu es tio

n 2.

C le ar

ca se

de fi ni tio

n 3.

C on

se cu tiv e ca se s

4. C om

pa ra bl e su bj ec ts

5. C le ar

in te rv en tio

n 6.

O M

de fi ne d,

va lid

& re lia bl e

7. A de qu at e fo llo w -u p le ng th

8. St at is tic al m et ho

ds w el l-d

es cr ib ed

9. R es ul ts

w el l-d

es cr ib ed

Q ua lit y ra tin

g:

Y N N R Y Y Y Y N /A Y

G oo

d St ua rt

et al .( 20 14 )

U K

• T he

an xi et y se ve ri ty

sc or e re du ce d fr om

BL to

PT ;h

ow ev er ,i t w as

st ill ab ov e

th e cl in ic al cu t- of fp

oi nt

at PT

. •

T he

de pr es si on

se ve ri ty

sc or e re du ce d

fr om

BL to

PT ;h

ow ev er ,i t w as

st ill

ab ov e th e cl in ic al cu t- of fp

oi nt

at PT

.

• In su ffi ci en t de ta il re ga rd in g th e

tr ea tm

en t co m po

ne nt s w as

pr ov id ed

• T he re

w as

no fo llo w -u p ou

tc om

e da ta

• La ck

of m ul tip

le ba se lin e

• N o fo rm

al di ag no

si s of

an xi et y

1. C le ar

st ud y qu es tio

n 2.

C le ar

ca se

de fi ni tio

n 3.

C on

se cu tiv e ca se s

4. C om

pa ra bl e su bj ec ts

5. C le ar

in te rv en tio

n 6.

O M

de fi ne d,

va lid

& re lia bl e

7. A de qu at e fo llo w -u p le ng th

Y Y N /A

N /A

Y Y N

Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

Elevated anxiety symptoms were largely determined using predetermined clinical cut-offs on standardised measures of anxiety symptomatology. One study reported that eligible participants demonstrated ‘anxiety issues’ in need of management, but did not elaborate on how this was determined (Marwood & Hewitt 2013). Two studies utilised a clinical diagnostic interview to determine anxiety diagnoses (Phillips & Klein-Tasman 2009; Roberts & Kwan 2018). Participants presented with a variety of anxious symptoms that were often associated with generalised anxiety, specific phobia and social anxiety.

Methodological quality

Tables 2–5 demonstrate the study strengths and weaknesses of the included studies, based on the NIH quality assessment tools. As can be seen in Tables 2–5, overall, two studies were classified as ‘good’, three studies were rated as ‘fair’ and four studies were rated as ‘poor’ on the overall quality ratings. Methodological strengths of the reviewed studies included the following: low attrition rates [80% (n = 4 out of 5) of pre–post studies]; representative samples [100% (n = 5 out of 5)]; clear study objectives [100% (n = 9 out of 9) of all studies]; and clear selection criteria for participants [80% (n = 4 out of 5)]. Sixty per cent of studies (n = 3 out of 5) included appropriate statistical analyses. Weaknesses of the reviewed studies included the following: lack of multiple baseline [0% (n = 5 out of 5)] and lack of blinded assessors [0% (n = 5 out of 5)].

Cognitive behavioural therapy delivery

Table 6 summarises the main features of each of the reviewed studies, such as therapy format (individual or group therapy), participant characteristics (e.g. age and ID levels), CBT treatment components utilised and types of modifications made. The reviewed studies used CBT interventions that ranged from 6 to 41 sessions in total, with a duration of 1–2 h per session. As can be seen from Table 6, four studies utilised individual CBT sessions, and the remaining five adopted a group-based CBT delivery. The group interventions included compulsory or optional support persons in therapy. All interventions were facilitated by a therapist. The qualifications of the therapist varied across studies and included registered

831

T ab

le 5.

(C on tin

ue d)

R ef er en

ce an

d co

un tr y

M ai n fi nd

in gs

† L im

it at io ns

M et ho

do lo gi ca

lq ua

lit y‡

8. St at is tic al m et ho

ds w el l-d

es cr ib ed

9. R es ul ts

w el l-d

es cr ib ed

Q ua lit y ra tin

g:

N /A

Y Po or

†

T he

ou tc om

e m ea su re s pr ov id e ba se lin e an d po

st -t re at m en t da ta .

‡

T he

m et ho

do lo gi ca lq

ua lit y of

st ud ie s w as

as se ss ed

us in g th e N IH

Q ua lit y A ss es sm

en t of

C as e Se ri es

St ud ie s. 1.

C le ar

st ud y qu es tio

n = W

as th e st ud y qu es tio

n or

ob je ct iv e cl ea rl y st at ed ?; 2.

C le ar

ca se

de fi ni tio

n = W

as th e st ud y po

pu la tio

n cl ea rl y an d fu lly

de sc ri be d,

in cl ud in g a ca se

de fi ni tio

n? ;3

.C on

se cu tiv e ca se s = W

er e th e ca se s co ns ec ut iv e? ;4

.C om

pa ra bl e su bj ec ts

= W

er e th e su bj ec ts

co m pa ra bl e? ;5

. C le ar

in te rv en tio

n = W

as th e in te rv en tio

n cl ea rl y de sc ri be d? ;6

.O M

de fi ne d,

va lid

& re lia bl e = W

er e th e ou

tc om

e m ea su re s cl ea rl y de fi ne d,

va lid ,r el ia bl e, an d im pl em

en te d co ns is te nt ly ac ro ss

al ls tu dy

pa rt ic -

ip an ts ?; 7. A de qu at e fo llo w -u p le ng th

= W

as th e le ng th

of fo llo w -u p ad eq ua te ?; 8. St at is tic al m et ho

ds w el l-d

es cr ib ed

= W

er e th e st at is tic al m et ho

ds w el l-d

es cr ib ed ?; 9. R es ul ts w el l-d

es cr ib ed

= W

er e th e re su lts

w el l-d

es cr ib ed ?

N ot e: BA

I, Be

ck A nx ie ty

In ve nt or y (B ec k et

al .1

98 8) ;B

D I, Be

ck D ep re ss io n In ve nt or y; G A S- ID ,G

la sg ow

A nx ie ty

Sc al e fo r pe op

le w ith

an In te lle ct ua lD

is ab ili ty

(M in dh am

& Es pi e 20 03

); G D S- LD

,G la sg ow

D ep re ss io n Sc al e fo r Pe op

le w ith

a Le ar ni ng

D is ab ili ty

(C ut hi ll et

al .2

00 3) .

BL ,b as el in e; C BT

,c og ni tiv e be ha vi ou

ra lt he ra py ;C

D ,c an no

td et er m in e; M ,g ro up

m ea n; m in ,m

in ut es ;N

,n o;

N ,n um

be r of

pa rt ic ip an ts ;N

/A ,n ot

ap pl ic ab le ;N

R ,n ot

re po

rt ed ;O

M ,o

ut co m e m ea su re ;P T ,p os t-

tr ea tm

en t; SD

,s ta nd ar d de vi at io n;

si g, si gn ifi ca nt ;s ig ,s ig ni fi ca nt ;U

K ,U

ni te d K in gd om

;Y ,y es .

Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

832

T ab

le 6

S ys te m at ic

re vi ew

su m m ar y of

fi n d in gs

ac ro ss

st u d ie s (N

= 9 )

T he

ra py

P ar ti ci pa

nt s

A nx

ie ty

ty pe

T re at m en

t co

m po

ne nt s

St ud

y In di vi du

al th er ap

y G ro

up th er ap

y B or

de rl in e/

m ild

ID M od

er at e/

se ve

re ID

N on

-s pe

ci fi ed

ID le ve

l U nd

er 18

ye ar s

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Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

clinical psychologists (Carrigan & Allez 2017), assistant or trainee psychologists (Douglass et al. 2007; Marwood & Hewitt 2013; Stuart et al. 2014; Giannaki & Hewitt 2021), learning disability nurses and occupational therapists (Douglass et al. 2007). Four studies did not specify the qualifications or training of the therapists (Lindsay et al. 1997; Phillips & Klein-Tasman 2009; Roberts & Kwan 2018; Blakeley-Smith et al. 2021).

Three studies reported that participants continued taking prescribed medication for anxiety or comorbid low mood throughout the study; however, the type and dose remained consistent for a considerable time prior and during the intervention (Marwood & Hewitt 2013; Stuart et al. 2014; Blakeley-Smith et al. 2021). The remainder of the studies did not report on medication use.

Child studies

Mixed anxiety

Amongst studies with child participants, one included participants aged 12–19 years (Phillips & Klein- Tasman 2009; Blakeley-Smith et al. 2021) and the other 13 years (Phillips & Klein-Tasman 2009), with various anxiety disorders and fears (e.g. generalised anxiety, separation anxiety and specific phobia) (refer to Table 2). Blakeley-Smith et al. (2021) included children/adolescents with a comorbid diagnosis of ASD and Phillips and Klein-Tasman (2009) included adolescents with comorbid diagnoses of Williams syndrome, ADHD and oppositional defiant disorder (ODD; Phillips & Klein-Tasman 2009).

Treatment components and adaptations. Several components were included across the two studies to treat various anxiety disorders; these included psychoeducation, relaxation, exposure, identifying unhelpful thoughts, thought replacement, cognitive restructuring and strategies to promote emotion regulation (refer to Table 6). However, Phillips and Klein-Tasman (2009) reported that exposure and cognitive restructuring were not routinely used or focused on.

Adaptations that were commonly applied across the two studies to accommodate for the needs of the children/adolescents included adopting a slower pace, rehearsing, involving parents in the intervention, and tailored support for problem behaviours.

Blakeley-Smith et al. (2021) reported that they adapted the intervention based off stakeholder input gained through informal focus groups, parent interviews and treatment acceptability ratings. Various modifications to the programme included reducing the length of sessions, having smaller groups, greater parental involvement in sessions, and providing information sessions to parents on various topics (e.g. the difficulty detecting anxiety in individuals with ID and ASD, and the interplay between anxiety and problem behaviour). They also reported including visual supports to teach strategies, video modelling, hands on activities and reinforcement of brave behaviour. On the other hand, Phillips and Klein-Tasman (2009) reported including techniques to encourage participants to cope with teasing to assist them with their anxiety in social situations and strategies to manage oppositional behaviours and emotional outbursts.

Strategies were tailored to the children’s/adolescents’ cognitive abilities. Blakeley-Smith et al. adapted the delivery of strategies based on the participants’ expressive language ability. For example, participants with communication difficulties were provided helpful thoughts (e.g. ‘I can do this, I’m brave’) with a visual structure instead of delivering cognitive restructuring (‘fight fear with facts’). Similarly, Phillips and Klein-Tasman (2009) delivered more straightforward behavioural strategies, such as thought replacement (‘adaptive self- statements’) instead of cognitive restructuring when participants had difficulties comprehending the material.

Treatment outcomes. Across the child/adolescent studies, there were positive results on the effectiveness of CBT on anxiety. Blakeley-Smith et al. (2021) found that following the intervention, there were significant improvements in the group mean of anxiety and minimal and moderate effect sizes on parent-reported measures of anxiety [e.g. Anxiety Depression and Mood Scale (ωp

2 = .45) and the total FSSC-R (ωp

2 = .20)]. Moreover, there were significant reductions in the total score and separation anxiety subscale of the SCARED-P, but not in the other subscales; they proposed that this may be because some domains of anxiety (e.g. generalised or social anxiety) are more difficult for parents to observe, relying more heavily on a child’s verbalisation of

833 Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

worry. Phillips and Klein-Tasman (2009) also found improvements in anxiety severity across some measures whereas others indicated no change or an exacerbation of symptoms. Following the intervention, the two participants no longer met the diagnostic criteria for various anxiety disorders recognised at pre-treatment; however, some remained clinical (Phillips & Klein-Tasman 2009).

Additional outcomes. Parent acceptability ratings, attendance and completion rates indicated that Blakeley-Smith et al.’s (2021) intervention was feasible to implement and valued by families. They also reported a significant reduction in symptoms of depression (ωp

2 = .23), mood symptoms (ωp 2 = .20)

and lethargy (ωp 2 = .14) in the group following a CBT

intervention, compared with baseline; still, these effects sizes were only minimal. However, significant reductions in symptoms of irritability were not observed, suggesting that problem behaviours were not impacted by the intervention. Phillips and Klein- Tasman (2009) also found significant improvements in emotional–behavioural difficulties, where one participant no longer met the criteria for ODD following treatment; however, it should be noted a considerable portion of the intervention focused on strategies specifically addressing emotional outbursts.

Adult studies

Generalised anxiety or mixed anxiety

Three studies included adults with diagnoses or symptoms of generalised anxiety, specific phobia, social anxiety or OCD (Marwood & Hewitt 2013; Roberts & Kwan 2018; Giannaki & Hewitt 2021) and one study included adults experiencing generalised anxiety (Douglass et al. 2007; refer to Table 3). Marwood and Hewitt (2013) included adult participants with comorbid diagnoses of ASD and depression.

Treatment component and adaptations. Various treatment components were included across the adult studies with generalised and mixed anxiety, such as psychoeducation and relaxation. Other behavioural strategies, such as distraction and thought replacement, were reported less (Douglass et al. 2007; Marwood & Hewitt 2013). While identifying unhelpful thoughts was a common component, only

one study included cognitive restructuring, whereby unhelpful thoughts were actively challenged (Roberts & Kwan 2018). Moreover, only two studies (Douglass et al. 2007; Roberts & Kwan 2018) incorporated exposure, providing minimal detail on this component; it was, however, unclear whether Douglass et al. (2007) only delivered this component to one participant.

Various modifications to the interventions for anxiety were referenced across the adult studies. Some studies modified treatments based off recommendations in the literature for adults with ID (e.g. Whitehouse et al. 2006) or the clinician’s previous work with the population (Roberts & Kwan 2018). Common adaptations applied across studies involved incorporating visual supports, roleplays, rehearsing strategies, simplifying language and including a support person. Studies proposed that including a support person who knew the participant well, was motivated and consistent was beneficial to treatment outcomes (Douglass et al. 2007; Marwood & Hewitt 2013). Other modifications that were used less included using games and stories to teach materials, having shorter sessions, adopting a slower pace and using concrete examples (Douglass et al. 2007; Giannaki & Hewitt 2021).

Across studies cognitive components were modified to cater for a participant’s cognitive capacity. Roberts and Kwan (2018) incorporated activities, roleplays and metaphors (e.g. changing red to green traffic light thoughts) to adapt cognitive challenging to meet the needs of adults with mild ID. Individuals with moderate ID benefited from additional modifications, such as extensive modelling, rehearsing and prompting. Douglass et al. (2007) endorsed a flexible approach when delivering cognitive strategies. When participants had difficulties identifying negative thoughts, roleplays were offered (which was of limited benefit) and participants were encouraged to practise ‘generic coping statements’.

Treatment outcomes. Across the adult studies examining the effectiveness of CBT for mixed anxiety presentations, significant reductions in self- and informant-reported anxiety scores were found. Giannaki and Hewitt (2021) found that all four participants in the study demonstrated significant improvements following treatment, which were

834 Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

largely maintained at follow-up. Correspondingly, Roberts and Kwan (2018) found moderate effect sizes for the improvements in self (r = .60) and informant ratings (r = .49) of anxiety severity for participants with mild to moderate ID following treatment. They also found that there was a significant reduction in the proportion of participants diagnosed with an anxiety disorder following the intervention (7.7%; n = 1) compared with that prior to the intervention (7.69%; n = 10).

However, some studies reported mixed results on the effectiveness of CBT on anxiety in adults with ID. For example, Douglass et al. (2007) found a significant reduction in anxiety for two out of six participants who presented with borderline–moderate ID; whereas, slight increases in anxiety were reported for three out of six participants. Similarly, Marwood and Hewitt (2013) observed significant reductions in anxiety for two out of eight participants with mild ID; however, slight increases in anxiety were observed for three participants. Marwood and Hewitt (2013) suggested results may have been impacted by the sensitivity of the measure used.

Additional outcomes. Studies reported improvements across additional measures, such as global functioning, distress, quality of life and mood. Giannaki and Hewitt (2021) observed significant improvements in the overall level of distress for most participants following the intervention, which was largely maintained at follow-up. In addition, significant improvements in global functioning were observed for half of the participants following the intervention. Marwood and Hewitt (2013) also observed improvements in the participants’ quality of life and global functioning following treatment. Furthermore, the completion rates across studies indicated that the interventions were well tolerated (Douglass et al. 2007; Giannaki & Hewitt 2021); however, two studies did not report on attrition rates (Marwood & Hewitt 2013; Roberts & Kwan 2018). Douglass et al. (2007) also found that participants developed coping skills following the intervention and that carers developed a greater understanding of the participants’ difficulties, according to qualitative feedback.

Studies reported on the participants’ ability to learn and demonstrate cognitive strategies. Giannaki and Hewitt (2021) found that during the post-treatment

interviews, no participant demonstrated an understanding of the impact of unhelpful thoughts on anxiety; they proposed this reflected an inability to link thoughts and emotions. Contrastingly, Roberts and Kwan (2018) found that most participants with mild ID were able to demonstrate competence with linking thoughts and emotions and other skills associated with cognitive restructuring (e.g. gather evidence on whether a thought is realistic, generate a more helpful or realistic belief). However, individuals with moderate ID demonstrated limited or no competence across most of these skills (besides identifying unhelpful and helpful thoughts). Therefore, a participant’s proficiency with cognitive restructuring appeared to be impacted by their level of ID.

Post-traumatic stress disorder

Carrigan and Allez (2017) delivered a trauma-focused CBT intervention to a young man with mild ID and ASD and symptoms consistent with PTSD (see Table 4). The intervention incorporated elements of cognitive therapy for PTSD.

Treatment component and adaptations. Carrigan and Allez (2017) delivered a CBT intervention for PTSD, which included psychoeducation on trauma and its sequelae (using a simplified model), cognitive restructuring, behavioural experiments and imaginal reliving. Strategies to address anger outbursts were also introduced towards the beginning of treatment. The authors described making only minimal modifications to cognitive therapy for PTSD. They found that with careful use of Socratic questioning, simplifying the language and explaining metaphors, they were able to help the participant overcome difficulties with applying abstract concepts to his own situation and to see alternate viewpoints when engaging in cognitive restructuring.

Treatment outcomes. There were improvements in the participants’ symptomatology following the intervention, whereby the severity of PTSD symptoms fell within the normal range on a screening measure (Carrigan & Allez 2017). This corresponded with qualitative improvements in the participants’ symptomatology (e.g. improved sleep, reduced

835 Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

nightmares and avoidance) as reported by the participant and their parent.

Non-specified anxiety

Two studies (Lindsay et al. 1997; Stuart et al. 2014) included adult participants with elevated anxiety that was not specified or diagnosed; these participants also presented with low mood, which was not formally assessed (see Table 5).

Treatment components and adaptations. Lindsay et al. (1997) reported delivering cognitive therapy based on the treatment by Beck et al. (1979) whereas Stuart and colleagues described delivering a behaviourally focused CBT intervention. The treatment in both studies included various components which included psychoeducation on the link between thoughts, feelings and behaviours, and noticing or identifying unhelpful thoughts. Lindsay et al.’s (1997) intervention focused on cognitive strategies, consistent with cognitive restructuring; whereas Stuart et al. (2014) focused on behavioural strategies, such as behavioural activation and relaxation.

Lindsay et al. (1997) and Stuart et al. (2014) described adopting various modifications, which included simplifying language, encouraging repetition and having a more activity-based approach. Lindsay et al. (1997) also included adaptions to help participants to elicit thoughts, practise more adaptive ways of thinking and overcome difficulties with abstract thought; these included using role plays, reversing the roles of therapist and client, plotting the sequence of events leading to anxiety and looking at photos of anxiety provoking situations (which may bear some resemblance to exposure practises).

Treatment and additional outcomes. Across the studies treating non-specified anxiety in adults with ID (Lindsay et al. 1997; Stuart et al. 2014), participants demonstrated improvements in the severity of anxiety and depression. Following intervention, Lindsay et al. (1997) found that one participant’s symptoms of anxiety and depression fell within the normal range, whereas Stuart et al. (2014) observed that the participants’ anxiety and low mood remained above the clinical cut-off.

Discussion

This systematic review explored the literature on the effectiveness of CBT for individuals with ID and anxiety. It sought to update the field to include more recent studies and to adopt a more stringent inclusion criteria to focus on studies that target anxiety (rather than transdiagnostic groups), thereby providing a more focused review on anxiety compared with previous reviews. It was also the first systematic review to examine the effectiveness of CBT for children/adolescents with ID and anxiety.

Across the nine studies reviewed, CBT interventions were found to have a positive effect on the severity levels of anxiety in children/adolescents and adults with ID; seven studies reported significant reductions in anxiety for 25%–100% of participants (N = 60) following a CBT intervention. These findings are encouraging; however, in light of the absence of any control groups and other methodological shortcomings, the conclusions that can be drawn are limited. The findings highlight that CBT for children/adolescents and adults with anxiety and mild ID may be feasible and tolerable for a variety of anxiety disorders. Positive outcomes were reported in line with previous reviews on the effectiveness of CBT for adults with ID and anxiety or depression (Unwin et al. 2016; Dagnan et al. 2018). Moreover, improvements generalised to overall functioning, general distress levels, quality of life and mood following the intervention. The results highlight that children/adolescents with various presentations of anxiety and comorbidities can tolerate and benefit from a CBT intervention that is tailored to their cognitive and behavioural needs. It also highlights the importance of a flexible approach in the delivery of strategies.

The studies that showed the most promising results (moderate effect sizes) (Roberts & Kwan 2018; Blakeley-Smith et al. 2021; Giannaki & Hewitt 2021) tended to be the more recent and methodologically rigorous studies, incorporating various cognitive and behavioural components of CBT and more modifications. Interestingly, Blakeley-Smith et al. (2021) and Roberts and Kwan (2018) were the only studies that routinely delivered exposure and cognitive restructuring or thought replacement. In light of the encouraging results, it may indicate the importance of these components in treating anxiety for adults and children with anxiety and ID; this is

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G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

consistent with findings in the TD literature that exposure and cognitive restructuring are key components in treating anxiety (Kaczkurkin & Foa 2015). However, additional case studies that included cognitive techniques (e.g. cognitive restructuring) in the absence of exposure demonstrated positive results indicating emerging evidence for cognitive components for individuals with mild ID (Lindsay et al. 1997; Carrigan & Allez 2017). Across the studies, individuals with mild ID and some with moderate ID appeared to benefit from learning about the link between thoughts, feelings and behaviours, strategies to identify unhelpful thoughts and relaxation strategies to understand and manage anxiety.

Pleasingly, the components of CBT were adapted to the needs of participants with ID across all studies. There was considerable overlap in the adaptations used across studies, regardless of the participants’ age or anxiety disorder. Many of the studies reported utilising adaptations, such as rehearsing techniques, involving a parent/support person, utilising smaller groups and adapting language. These modifications were consistent with the recommendations from the literature (Hronis et al. 2017). Nevertheless, many of the included studies lacked sufficient detail regarding the nature of the modifications, which poses challenges for the replication and development of treatment modifications. Moreover, several studies included modules or strategies in interventions to accommodate comorbidities, problem behaviours and difficulties with emotion regulation; this resulted in significant improvements in behaviours that challenge in some cases (e.g. Phillips & Klein- Tasman 2009). Blakeley-Smith et al. (2021) however proposed that the anxiety intervention was not helpful in targeting problem behaviour and suggested an additional module addressing these concerns may be warranted for some individuals prior to the CBT anxiety intervention. Therefore, future studies may benefit from tailoring intervention to the participants’ cognitive capacity, comorbidities and emotion regulation concerns.

Across the studies, it was apparent that a flexible approach towards the delivery of cognitive skills was beneficial to accommodate for the age and the cognitive capacity of each person. Some children/adolescents and adults with mild ID (or who

were verbally fluent) were found to effectively engage with and implement key components of cognitive restructuring; this included individuals presenting with a variety of anxiety disorders (e.g. generalised anxiety, social anxiety and PTSD). The use of Socratic questioning was found to be important in facilitating the process of challenging negative thoughts and generating more helpful thoughts. Participants with a moderate ID (or emerging language skills) were often able to identify helpful and unhelpful thoughts with certain accommodations but struggled with the use of more conceptual strategies, such as cognitive restructuring. Participants with a moderate ID tended to benefit from a more directive and simplified approach involving the use of thought replacement, whereby participants reminded themselves of coping statements. They also benefited from extensive modelling, rehearsing, prompting and the use of visual aids, regardless of their age. Therefore, cognitive strategies, such as cognitive restructuring, appear to be beneficial and feasible for children and adolescents with mild ID with the use of appropriate modifications and a flexible approach.

Strengths of the studies include using measures that were standardised, valid and reliable, having low attrition rates, and including participants with elevated levels of anxiety. In addition, most of the studies used a measure of anxiety that was developed for the ID population. However, a number of limitations were observed. For example, the studies lacked a control condition and utilised small sample sizes, which underpowered the results. The majority of the studies did not include follow-up assessment to ascertain the long-term maintenance of the intervention, so this remains uncertain. Most of the studies relied upon self-report measures, and no studies included blinded assessors, which increased the risk of bias. Many studies did not utilise appropriate statistical analyses or multiple baseline outcome data, which is important as it allows for inferences to be made about the effectiveness of an intervention. Therefore, despite some strengths, there were considerable methodological limitations across the studies reviewed, so current conclusions are preliminary.

The studies included in this review differed across several domains, which may have affected treatment outcomes. First, there was variability in the inclusion criteria for participants across studies, such that some

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G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

studies required a clinical diagnosis of an anxiety disorder, whereas others required elevated anxiety symptomatology based on questionnaire data. Consequently, some studies may have included participants with subclinical anxiety, resulting in limited reductions in anxiety due to a floor effect. Also, the majority of studies relied upon self-report measures of anxiety, some of which had not been validated in the ID population (e.g. Carrigan & Allez 2017). While self-report measures are desirable in measuring internal states, such as anxiety, the validity of an individual’s self-report may be impacted by factors associated with having an ID; these factors include difficulties with memory, social desirability, response bias and acquiescence (Willner 2005). These challenges in assessment may be alleviated in part by collecting information from multiple informants; however, only two studies included in this review adopted this approach (Phillips & Klein- Tasman 2009; Roberts & Kwan 2018). Therefore, these methodological and assessment limitations may have impacted treatment outcomes.

There was also variability across studies in terms of the delivery of interventions. There was unclear terminology used in interventions across studies. For example, some studies reported including the technique ‘positive self-talk’ (Douglass et al. 2007) while others referred to ‘helpful thoughts’ (Blakeley- Smith et al. 2021), ‘adaptive self-statements’(Phillips & Klein-Tasman 2009) or ‘cognitive challenging’ (Roberts & Kwan 2018). Therefore, the line delineating between specific techniques was at times blurred, especially in cases where there was limited information on the interventions delivered. Finally, there was variability across studies in terms of the skill and training of therapists. Some therapists were trainee psychologists, while others were occupational therapists, endorsed clinical psychologists, or in some cases, it was not reported. Therefore, the outcomes of CBT interventions may have been influenced by the level of training that practitioners received in CBT and in working with individuals with ID. Thus, the studies included have a number of shortcomings and disparities, which may have impacted the treatment findings.

Future research may benefit from addressing these discrepancies and limitations by (1) incorporating more rigorous methodologies, which include a formal diagnosis of anxiety and ID; (2) utilising clear and

universally accepted descriptors of interventions including the treatment components; (3) providing clear details around the procedural modifications made to the delivery of CBT; (4) including follow-up outcome measures and/or multiple outcome data; (5) collecting information from unbiased assessors and/or multiple informants; (6) validating and adapting existing measures of anxiety in the ID population; (7) exploring what modifications to CBT interventions are helpful for individuals with varying levels of ID, particularly through focus groups; (8) utilising large-scale RCTs to evaluate the effectiveness of CBT for the ID population and to explore which CBT components are most effective in treating anxiety and which adaptations may be necessary for varying levels of ID; (9) evaluating more flexible interventions that may be adapted to the verbal competencies of the participants, as seen in the intervention delivered by Blakeley-Smith et al. (2021); and (10) developing evidence-manualised treatments that are tailored to the needs of individuals with mild or moderate ID.

This systematic review employed rigorous criteria to identify eligible studies. Eligible studies were required to present pre- and post-outcome measures of anxiety and did not include interventions, which targeted mixed presentations (i.e. conditions other than anxiety). However, there were several limitations of this systematic review. First, only studies in English were considered, and consequently, most studies were completed in the UK, with some in the USA and Australia. Therefore, the findings of this review may have limited generalisability to other regions or cul- tures. Additionally, the inclusion criteria for the presence of ID allowed for participants who had been referred from an ID service provider; therefore, par- ticipants may have been included that are not truly representative of people with ID. Furthermore, the search terms for ID were narrow and may have re- sulted in some papers examining other related con- ditions (e.g. Fragile X syndrome) being missed. Most of the studies included in this review were composed of participants with a mild ID. Therefore, the findings of the present review may have limited generalisability to participants with moderate or severe ID, and even borderline impaired IQ. Studies were also included that reported on comorbid ASD diagnosis; it is un- clear whether the treatment modifications may gen- eralise to the broader ID population due to the distinct profile of ASD.

838 Journal of Intellectual Disability Research VOLUME 67 PART 9 SEPTEMBER 2023

G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

© 2023 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the

Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

The current systematic review explored the literature on the effectiveness of CBT for anxiety in individuals with ID, an area that is grossly under- researched. Findings suggest that CBT is a promising treatment for individuals with mild ID and anxiety. Although strong recommendations regarding treatment effectiveness cannot be made at this time due to the limited number of studies and methodological limitations in the research, there is tentative evidence for techniques such as cognitive restructuring and thought replacement and modifications such as visual aids, modelling and smaller groups, at least for those aged 12 years and over. The current review highlights a clear need for future studies to incorporate more scientifically rigorous methodologies to address the limitations identified in this review and identified gaps in the literature. It also reveals that there is a lack of emphasis on the ID population in the mental health literature and that there is a need for more training for practitioners working alongside individuals with ID. Most pertinently, research needs to focus on the development of evidence-based treatment protocols and clinical practise guidelines. Studies on the effectiveness of CBT for different levels of ID with various modifications will better inform the recommendations for treatments for individuals with ID and anxiety. Ultimately, this will assist individuals with ID experiencing anxiety to have access to effective treatments that are tailored to their ability levels and their needs.

Acknowledgements

We extend our gratitude to the reviewers and editors for their feedback.

Open access publishing facilitated by Macquarie University, as part of the Wiley - Macquarie University agreement via the Council of Australian University Librarians.

Source of funding

No external funding was received for the research reported in the paper.

Conflict of interest

There are no conflicts of interest. This is a systematic review and no human ethics approval was required.

Data availability statement

Data available on request.

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Accepted 12 May 2023

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G. Fynn et al. • The effectiveness of cognitive behavioural therapy for individuals with an intellectual disability and anxiety: a systematic review

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Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

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