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Assessment of mental health problems in people with intellectual disabilities

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Assessment of Mental Health Problems in People with Intellectual Disabilities

Helen Costello, PhD, and Nick Bouras, MD, PhD, FRC Psych

King’s College London, Institute of Psychiatry, Estia Centre, Munro–Guy’s Hospital, London, United Kingdom.

Abstract: Although it is widely accepted that individuals with intellectul disabilities face an increased vulnerability to developing mental health problems, there is currently a lack of agreement about the most appropriate form of assess- ment. When applied to people with intellectual disabilities, there is no consensus about which problems should be in- cluded in the term “mental health problem,” and identifying mental illness is far from straightforward. The adoption of standardized classification systems assumes that individuals with intellectual disabilities have adequate linguistic skills and they present mental health problems in the same way as members of the general population. Yet, individuals with intellectual disabilities are less likely to fulfill verbal expectations that are the basis of current classification sys- tems and many exhibit problem behaviors incompatible with existing criteria. Nevertheless, accurate diagnosis pro- vides a clear direction for interventions. Although there is currently a lack of consensus about which instruments are most effective, the routine use of valid and reliable assessment and monitoring tools may significantly improve the quality of research and care. The complexity of factors influencing the mental health of individuals with intellectual disabilities has implications for how these needs can be effectively met. Clearly, diagnostic classification provides only partial guidance to morbidity and the quality of life experienced and mental health services increasingly adopt a prob- lem-based, “biopsychosocial” approach to assessment and treatment delivered by multidisciplinary teams. The most basic and vital role of carers within this context is the awareness that a person with intellectual disabilities may suffer from a mental illness. Carers play a central role in recognising possible mental illness, making referrals for further psy- chiatric assessment and providing diagnostic information and treatment feedback. In the absence of information about the manifestation of mental health problems in individuals with intellectual disabilities, it is likely that the signs of mental illness will be overlooked. Training initiatives, aimed at increasing the ability of care staff to recognise the signs of mental illness and to make informed referral decisions, are vital in ensuring adequate access to mental health services by individuals with intellectual disabilities.

Introduction

Assessing the presence of mental health problems in individuals with intellectual disabilities is a complex process, which raises distinct theoretical questions and methodological dilemmas. These relate to the definition of mental health problems, the nature of psychiatric assessment and the classification of prob- lem behaviors. This article describes the prevalence of mental heath problems, highlights key assump- tions underlying the assessment process and consid- ers the implications for community services in meeting the mental health needs of individuals with intellectual disabilities.

Prevalence of Mental Health Problems in Persons with Intellectual Disability

Although substantially increased in recent years, re- search evidence about the prevalence of mental health problems in individuals with intellectual dis- abilities and the risk factors for developing specific psychiatric disorders is limited and often conflicting. Most estimates of the prevalence of psychiatric ill- ness in people with intellectual disabilities range from 10–39% (1–5). Predictably, a relatively high prevalence is reported by studies using screening in- struments to detect the presence of mental health problems. For example, in a small sample (n=127) based in a single GP (general practitioner) practice of an urban city, Roy et al. (2) reported an overall prevalence of 33% using the PAS-ADD checklist (6).

Isr J Psychiatry Relat Sci Vol 43 No. 4 (2006) 241–251

Address for Correspondence: Professor Nick Bouras, King’s College London, Institute of Psychiatry, Estia Centre, Munro–Guy’s Hospital, 66 Snowsfields, London SE1 3SS, United Kingdom. E-mail: [email protected]

Using the same screening instrument, a larger study of 1,155 adults with intellectual disabilities in a county district of North East England reported an overall prevalence of 20.1% (7). In contrast, Deb et al. (1) measured the prevalence of functional psychi- atric illness in an administratively defined random sample of 101 adults with intellectual disabilities liv- ing in the community (n=246). Enhancing compari- son with studies of the general population, a blind two-stage diagnostic procedure including standard- ized, valid and reliable assessment instruments and ICD-10 criteria (8), was used. Information was col- lected through clinical interview with informants and 89% of the individuals with intellectual disabili- ties. Deb et al. (1) report an overall prevalence of 14.4% for this. This compares to 16% found for the general population using the same criteria (9). The authors concluded that the prevalence of functional psychiatric illness in people with intellectual disabil- ities was similar to that found in the general popula- tion, although rates of schizophrenic illness and phobic disorder were significantly higher in the study cohort than in general population.

Moss (10) measured the one-month period prev- alence of psychiatric disorders in a cross-sectional descriptive study (n=146) comprising a randomized sample drawn from a health and social service regis- ter in North West England (1996–1998) (n=710). Data were collected through the Psychiatric Assess- ment Schedule for Adults with Developmental Dis- abilities (PAS-ADD) (11), completed with respondents and informants in conjunction with ICD-10 (8) and DSM-IV clinical diagnoses (12). As in the Deb et al. study (1), behavior disorders, per- sonality disorders and Pervasive Developmental Disorders were excluded. The results were compared with an OPCS study (13) of the general population also using ICD-10 (8) (n=10108). This study found an overall 12.3% prevalence compared to 14.7% re- ported by OPCS (13). Moss (10) concluded that using ICD-10 (8), the prevalence of psychiatric dis- orders in adults with intellectual disabilities was sim- ilar to that found in the general population. However, he cautions that ICD-10 (8) may under-di- agnose certain disorders such as psychotic disorders. Indeed, using DSM-IV clinical diagnosis (12), a prevalence of 26.0% was found in the same sample.

Although most categories of mental illness have

been reported in this population (14–16), the pattern of prevalence in people with intellectual disabilities may well differ from that found in the general popu- lation (17). For example, in the studies described above, Deb (1) and Moss (10) reported a point prev- alence of 3% (range 1.3% to 3.7%) and 2.7% respec- tively for schizophrenia. This compares to 0.4% in the general population (9). Consensus about the rea- sons for increased prevalence of schizophrenia has yet to be reached (18). Explanations include the pres- ence of underlying brain damage, the difficulty in detecting complex subjective symptoms (19) and a persistent clinical bias to “think schizophrenia first” in the presence of psychotic symptoms (20, 21). In contrast, diagnoses of disorders such as depression, which occur the most frequently in the general pop- ulation, appear less common in people with intellec- tual disabilities (14). The point prevalence of depressive disorder ranges from 1.3% to 3.7% in in- dividuals with intellectual disabilities (1, 5, 22) and is 15% for the general population (9).

There is limited evidence currently regarding the factors predicting the presence of mental health problems in individuals with intellectual disabilities. As for the general population (e.g., 23), gender and age have been identified as risk factors for devel- oping certain psychiatric disorders. For example, Cooper (3) reports a higher prevalence of psychiatric disorders in older individuals with intellectual dis- abilities, particularly for depression and anxiety. There is also growing evidence to suggest that cer- tain genetic syndromes may predispose individuals to developing particular mental disorders. There- fore, the aetiology of intellectual disabilities may af- fect the rate of psychiatric disorder. For example, Collacott et al. (24) showed that individuals with Down syndrome had higher rates for depression and dementia. In contrast, after controlling for the level of intellectual disabilities, Haveman et al. (25) dem- onstrated much lower prevalence rates for psychiat- ric disorder in people with Down syndrome. Opinion varies about how the severity of intellectual disabilities affects an individual’s vulnerability to de- veloping different psychiatric disorders (18). The re- spective rates of psychopathology in people with mild or moderate intellectual disabilities and people with severe and profound intellectual disabilities vary across studies. Gostason (26) and Lund (27)

242 ASSESSMENT OF MENTAL HEALTH PROBLEMS IN PEOPLE WITH INTELLECTUAL DISABILITIES

showed higher rates of psychiatric illness in people with severe intellectual disabilities, whereas Iverson and Fox (28), Jacobson (29) and Borthwick-Duffy and Eyman (30) all showed a higher prevalence in adults with mild intellectual disabilities. Corbett (31) found no evidence either way.

To summarize, research suggests that the preva- lence of mental health problems in individuals with intellectual disabilities is at least as high, although probably higher, than in the general population. As discussed in the following sections, individuals with intellectual disabilities form a heterogeneous popu- lation and the application of measurement tech- niques developed for the general population is problematic. As such, studies comparing the pres- ence of mental health problems in individuals with and without intellectual disabilities using common assessment criteria are yet to be conducted and may be inappropriate.

Assessment

Hampered by a lack of validated diagnostic instru- ments (32), studies have adopted a broad range of approaches to measuring psychopathology with many failing to report operational definitions ade- quately (4). As yet, the equivalence of measurement techniques is uncertain (33), although prevalence es- timates reliant upon routine clinical assessment for diagnosis generate higher estimates than those studies using standardized methods or case notes (1, 34). Prevalence estimates are also heavily influenced by sample selection (4, 34) and until recently many studies relied upon institutional or administrative samples. This may lead to sampling bias and to the inflation of prevalence because each of these groups is more likely to have mental health problems com- pared to the population at risk (30). Furthermore, studies examining the complete spectrum of psychi- atric disorders are rare and the focus of diagnostic enquiry often varies from one study to another. Ap- parent differences in morbidity between the general population and individuals with intellectual disabili- ties may therefore partly reflect uneven diagnostic enquiry.

Therefore, in interpreting evidence about the presence of mental health problems in individuals with intellectual disabilities it is necessary to con-

sider the methodology employed and the assump- tions underlying the assessment process. Key issues relate to the definition of mental health problems and the nature of psychiatric assessment.

The definition of mental health problems Estimates of prevalence depend greatly on the defi- nition of a mental health problem and the definition of a case. When applied to people with intellectual disabilities, there is no consensus about which prob- lems should be included in the term “mental health problem” (35). Diverse conceptualizations of both intellectual disabilities and mental health are evident in the research literature (35). A variety of terms are used including mental illness, mental disorders, psy- chiatric disorder, emotional disorder and behavioral disorder. These labels are used interchangeably and the range of terms reflects the theoretical back- grounds of the assessor rather than a specific cate- gory (36). One solution has been to use the overarching term “mental health problem” to indi- cate the presence of psychopathology (symptoms, signs or abnormal traits). This approach encom- passes both single significant behaviors and clusters of symptoms occurring as part of a psychiatric illness such as schizophrenia and acknowledges that, as de- scribed subsequently, many behavioral problems are a complex mix of difficult to classify symptoms.

Therefore, the definition and identification of “mental illness” is far from straightforward (35). Mental health problems are socially defined and, as a result, they are highly interactive with the context in which the person lives and the social expectations placed upon him/her. In defining mental health, a whole range of factors needs to be taken into consid- eration, encompassing not just the individual, but also the wider ecology within which the person lives (37). Both personal and external social factors deter- mine whether a given set of symptoms results in pre- sentation to a doctor and a person becomes a “case” (38). Indeed, most mental health problems do not come to the attention of mental health services. Falloon and Fadden (39) estimated that support net- works such as family and friends are able to manage 90–95% of all cases of mental disorder in the com- munity. Inevitably, psychiatric assistance is more likely to be sought when conditions cause a high de- gree of debilitation. In the general population, iden-

HELEN COSTELLO AND NICK BOURAS 243

tification of a mental health problem is often prompted by the failure to maintain social roles such as employment and parenting. In contrast, individu- als with intellectual disabilities generally have fewer role expectations and the severity of symptoms does not necessarily relate to the degree of impairment in daily life. As a result, the impact of mental health problems on the individual’s life and upon those of others, such as carers, may be less visible. This re- duces the likelihood that mental health problems will be recognised by carers. As a result, conditions such as anxiety and depression may be clearly mani- fested and may cause significant distress to an indi- vidual, yet remain unrecognised.

The nature of psychiatric assessment Standardized classification systems of psychiatric disorders such as DSM-IV (12) and ICD-10 (8) are often adopted in studies of mental health problems in people with intellectual disabilities. Such systems provide a common discourse among researchers and clinicians and are an important clinical tool in medi- cation and other forms of treatment. They can also be used as a basis for designing assessment and screening instruments. Adopting standardized crite- ria to measure prevalence increases comparison with findings for the general population. However, its equivalence in individuals with and without intellec- tual disabilities is not known. Also, interpreting the study findings within the context of other prevalence studies of intellectually disabled populations be- comes more problematic. This is because it often en- tails making assumptions about the methods used to identify disorder in such studies.

Psychiatric assessment is concerned with identi- fying and matching patterns of symptoms with those of previously defined disorders, such as depression and schizophrenia, which in turn have a predictive value with respect to prognosis and treatment (35). Diagnosis is determined by the interaction of a vari- ety of factors: what the person says they are experi- encing; what others say about them; how they are seen to behave; and the history of their complaint. Psychiatric disorders have a period of onset and rep- resent deterioration in behavior from the pre-mor- bid state (40). Therefore, establishing a baseline and recording clinical history are central to the diagnos- tic process. The problem is regarded as being “within

the individual” and treatment focuses on the diag- nosed disorder rather than on specific symptoms (10). Two factors influence the applicability of stan- dardized assessment criteria to individuals with in- tellectual disabilities — linguistic skills and the presentation of mental health problems.

Linguistic skills

Diagnostic systems such as ICD-10 (8) rely upon verbal accounts of symptoms. A reduced ability to conceptualize and to express emotions places people with intellectual disabilities at a disadvantage in re- spect of this form of assessment. The applicability of standardized classification systems to members of this population is therefore influenced by the lin- guistic skills of the individual being assessed. Al- though people with intellectual disabilities can often provide reliable and valid information about symp- toms, parallel interviewing of both the patient and a key informant is essential for effective case detection (41). Some features of mental illness are very com- plex and require a high level of verbal fluency to de- scribe them. In people of average ability, a high degree of symptom differentiation is possible, but in individuals with limited or no verbal skills fine dis- crimination between symptoms is often impossible. Even in verbally competent individuals with intellec- tual disabilities, Moss et al. (41) found that the only first-rank symptom that could be detected with any frequency in psychiatric interviews was auditory hallucinations.

Hence, within this context, information about how the individuals themselves regard their current experiences is limited and is often totally absent. As a result non-verbal behavior, historical information and observations from informants such as family members or staff carers play a more prominent role. Reliance upon third party reports for assessment and diagnosis increases with the severity of an individ- ual’s intellectual disabilities. This has serious impli- cations for the quality of information yielded and, as a consequence, the validity of diagnoses, especially in non-verbal people, is uncertain (17). Indeed, the application of standardized criteria across the whole spectrum of intellectual disabilities and in particular the difficulties in diagnosing psychiatric disorders in individuals with severe levels of disabilities may partly account for reported discrepancies in the re-

244 ASSESSMENT OF MENTAL HEALTH PROBLEMS IN PEOPLE WITH INTELLECTUAL DISABILITIES

spective morbidity in individuals with and without intellectual disabilities.

A variety of factors may influence the quality of informant observations including the nature of the relationship between the informant and the person being assessed and the prior existence of a label such as “challenging behavior.” Little is known about the comparability of ratings made by different types of informant (42), and there is uncertainty about how conflicting informant information should be recon- ciled. The validity of the informant interview is also dependent on the condition in question. Inevitably, informants are more aware of symptoms with clear behavioral manifestations than of subjectively expe- rienced phenomena such as thought disorder or anx- iety. Informants are more likely to report worry, loss of interest, social withdrawal and irritability, whereas individuals with intellectual disabilities more fre- quently report autonomic symptoms and psychotic phenomena whose impact on behavior is often hard for informants to evaluate (41). Such differences in perspective may have a crucial impact on diagnostic conclusions.

The presentation of mental health problems

The application of standardized classification sys- tems to individuals with intellectual disabilities as- sumes that they express mental health problems in the same way as individuals in the general popula- tion. Yet, a variety of factors, common to both popu- lations, determine manifestation. These include: the person’s usual level of cognitive, communicative, physical and social functioning; the individual’s usual behavioral repertoire together with past and present interpersonal, cultural and environmental influences (43). Some studies suggest that psychiat- ric symptoms are essentially the same in this popula- tion as they are in the general population. For example, Sovner and Hurley (14) found that while impaired social functioning influenced clinical pre- sentation, it did not affect symptomatology. How- ever, important differences are also evident. In diagnosing mental illness, it is necessary to differen- tiate between symptoms that are part of an illness and signs and symptoms that are an expression of underlying brain damage (1). For example, it is im- portant to distinguish between intellectual disabili- ties and the negative symptoms of schizophrenia

such as slowness of thought and poverty of speech (44). In some cases, the presence of intellectual dis- abilities may overshadow problem behaviors usually considered indicative of psychopathology. As a re- sult, the signs of mental health problems are incor- rectly ascribed to an intellectual disability and “diagnostic overshadowing” occurs (45). As yet, it is unclear how such diagnostic overshadowing varies by clinical context, professional discipline or service user characteristics (46).

Generally, adults with mild intellectual disabili- ties and reasonable verbal skills exhibit symptoms that are similar, although possibly less complex, than those witnessed in the general population. “Psychosocial masking” (47), such as impoverished social skills and life experiences typical of this popu- lation, may lead to symptoms which may not seem as “rich” as in the general population. For example, ag- gressive acting out, withdrawal and/or somatic com- plaints may be observed instead of more typical depressive symptoms such as feelings of hopeless- ness (48). “Cognitive disintegration” may also imply that many people with intellectual disabilities have lower thresholds for anxiety to become overwhelm- ing and to impair cognitive function (47). Also, dis- turbed or regressed behaviors, physical signs and complaints such as headaches and abdominal pains are more common in individuals with moderate and severe intellectual disabilities (49). Further differ- ences in presentation include the common occur- rence of some symptoms that are “atypical” and unusual in the general population. Examples include the onset or increases in specific maladaptive behav- iors such as screaming, aggression and self-injury (50–53).

Mental Health Problems Versus Challenging Behavior

While it may be more valid to apply standardized cri- teria to individuals with mild intellectual disabilities (54), people with severe intellectual disabilities dis- play many behaviors which are incompatible with existing criteria. As such, they pose a special chal- lenge to current mental health classification systems. Moss (10) argues that this does not imply that such behaviors are not the signs of mental health prob- lems and that current classification systems are of

HELEN COSTELLO AND NICK BOURAS 245

limited value to this particular population. The in- clusion or exclusion of behavioral problems as a psy- chiatric disorder has a huge impact on the estimated prevalence of mental health problems. Where be- havioral disorders are included, prevalence is signifi- cantly higher and includes a large proportion of personality disorders (32). Deb et al. (1) suggest that if behavioral disorders, personality disorders, autism and ADHD are excluded, then the overall rate of psy- chiatric illness does not differ significantly from the general population. Yet, 16.7% of people with intel- lectual disabilities in the UK have challenging behav- ior (21), and it is the most common reason for referral to psychiatric services and accounts for a third of the admissions to psychiatric units from the community (55). Examples include aggressive, de- structive, attention seeking, sexually inappropriate, self-injurious, noisy, hyperactive and socially inap- propriate behaviors.

Emerson (56) defined challenging behavior as “culturally abnormal behaviour of such an intensity, frequency or duration that the physical safety of the person or others is likely to be placed in serious jeop- ardy, or behaviour which is likely to seriously limit use of, or result in the person being denied access to, ordinary community facilities.” Hence, challenging behavior is not a diagnostic category. Rather it is used to quantify the needs of individuals with intel- lectual disabilities in community services. Whether behavior is judged to be “challenging” or not is deter- mined by a combination of what the person does, the setting in which they do it and how their behavior is interpreted (1). As a result, challenging behaviors are likely to vary in their form and in the psychological and/or biological processes that underlie them (21). Such behavioral problems are often long-term be- havior patterns without a predictable time course, and there is confusion regarding the conditions under which a challenging behavior meets the for- mal diagnostic criteria for a psychiatric diagnosis. A number of possible links between challenging be- haviors and psychiatric disorders have been sug- gested (57). Hypotheses include: a) Challenging behavior and mental illness have the same biological basis and, in some cases, the biological basis that normally produces a challenging behavior may be expressed as a psychiatric disorder; b) challenging behavior may be an expression of mental illness; and

c) challenging behavior and mental illness may be linked on an operant basis, whereby challenging be- havior may occur in order to terminate aversive events during periods of mental illness.

Few studies address the relationship between challenging behaviors and mental illness, but it is likely that some challenging behavior is caused or ex- acerbated by a co-existing psychiatric disorder (57). Some studies demonstrate a positive relationship be- tween the severity of challenging behavior and the prevalence of psychiatric symptoms. For example, Moss and colleagues (34) found that depression was four times as prevalent in people with more demand- ing challenging behavior compared to people with- out challenging behavior. However, other studies such as Tsiouris et al. (58) found no evidence that challenging behaviors were depressive equivalents in individuals with intellectual disabilities. Ultimately, behavioral disturbances in people with intellectual disabilities are a complex mix of symptoms of multi- ple origins. Determining whether behaviors are the result of organic conditions, psychiatric disorders, environmental influences, or a combination of these, is often very difficult. For example, in some cases, behavioral problems may affect a person’s interper- sonal skills without underlying psychopathology, but in others, the same behaviors and stunted social de- velopment may be symptoms of underlying mental illness (59). Evaluating the relative contributions of these factors to the observed signs and symptoms is a core element of the assessment process.

To summarize, the terms challenging behavior and mental health problems represent two distinct approaches to understanding problem behaviors in individuals with mental health problems. Challeng- ing behavior is not a disorder, but recognition of the extent to which behavior has some adverse effect on the individual or others concerned with supporting that individual. As such its definition and identifica- tion refers not to the form of the behavior, but to its impact. While in some cases, each of these terms may be used to describe the same behavior, the status of challenging behaviors within psychiatry is uncer- tain and its relationship to mental health problems is unclear. For example, research is yet to establish under what circumstances a challenging behavior represents a separate entity, when it is an idiosyn- cratic expression of a mental health problem and

246 ASSESSMENT OF MENTAL HEALTH PROBLEMS IN PEOPLE WITH INTELLECTUAL DISABILITIES

when it is a contributory factor. Ultimately, the dis- tinction between challenging behavior and mental health problems may be artificial and too simplistic. In virtually every psychiatric disorder there may be behavioral manifestations that are learned, condi- tioned by environmental factors or under voluntary control. Nevertheless, identifying those individuals with challenging behavior resulting from a psychiat- ric disorder is crucial in improving that individual’s quality of life and in ensuring that adequate care plans and appropriate support and training for carers is in place. For example, having a formal diag- nosis of a psychiatric disorder rather than a non-spe- cific description of challenging behavior is very important because a diagnosis may lead to specific treatment.

Implications for Community Services in Meeting Mental Health Needs

Large numbers of individuals with intellectual dis- abilities living in the community exhibit psychiatric or behavioral problems arising from mental health problems. Together the joint contributions of mental illness and intellectual disabilities indicate a group of individuals whose needs are considerable, and whose quality of life will be seriously impaired if the illness is not effectively identified and treated (22, 60). Following de-institutionalization, there was a need to identify, treat and manage the mental health problems of people with intellectual disabilities in the community (54). Behavioral and psychiatric dis- orders are crucial determinants of the level and costs of specialist support an individual requires to live in- dependently in the community (32). Yet the com- plexity of factors influencing the mental health of individuals with intellectual disabilities has implica- tions for how these needs can be effectively met.

In terms of assessment, the accurate diagnosis of mental illness provides a clear direction for biomedi- cal interventions (34). Clearly, diagnostic classifica- tion provides only partial guidance to morbidity and the quality of life experienced by individuals with mental illness (39). Increased clinical and research attention in recent years has resulted in the develop- ment of a range of assessment instruments aimed at improving the identification and diagnosis of psy- chiatric and behavioral disorders in this population.

The routine use of valid and reliable assessment and monitoring tools may make a significant contribu- tion to improving the quality of care. Yet currently there is no consensus about which assessment in- struments should be used. Research has begun to focus on the adaptation of existing classification sys- tems for use with people with intellectual disabilities. For example, Moss and colleagues (11) developed the “PAS-ADD” (Psychiatric Assessment Schedule for Adults with Developmental Disabilities), a psy- chiatric interview based on ICD-10 criteria (8) which combines information from self-reports of in- dividuals with intellectual disabilities and from key informants.

The application of standard psychiatric diagnos- tic criteria to adults with severe and profound levels of intellectual disabilities is not supported at this time by many experienced researchers (61). For peo- ple with a moderate or greater degree of intellectual disabilities, specially developed carer or clinician- completed instruments are probably required. An al- ternative solution may be to devise a separate diag- nostic framework specifically for adults with intellectual disabilities or to modify existing catego- ries of disorder to take account of the differences due to intellectual disabilities. The DC-LD (diagnostic criteria for use with adults with intellectual disabili- ties) (62) is one example of a new set of diagnostic categories specifically designed for individuals with moderate to profound intellectual disabilities. These criteria are based on the ICD framework and were developed on the basis of expert clinical consensus. Assessment and monitoring tools based on these cri- teria are awaited. See Mohr and Costello (63), Rush et al. (64) and Hatton (65) for reviews of assessment and monitoring tools designed for measuring mental health problems in individuals with intellectual dis- abilities.

Today, mental health services increasingly adopt a problem-based, rather than a strictly diagnostic ap- proach. Emphasis is placed upon multidisciplinary teams, providing a coordinated and comprehensive “biopsychosocial” approach to assessment and treat- ment (66). Assessment must therefore extend be- yond the clinical interview and incorporate the wider aspects of a person’s life, such as ability to cope with life transitions and the adequacy of support net- works. This broad approach implies that a range of

HELEN COSTELLO AND NICK BOURAS 247

agencies, including carers and individuals with intel- lectual disabilities, work together in order to maxi- mize the gathering of developmental, background, functional, behavioral and observational data (43). This has implications for residential service re- sponses, both in terms of staffing ratios and the range of necessary staff skills.

The role of carers Limited communication skills imply that many peo- ple with intellectual disabilities experience difficul- ties in articulating their mental health problems. In contrast to members of the general population, the decision to seek help is not made by the person with intellectual disabilities him or herself (67). Access to appropriate treatment is therefore dependent upon family and staff carers recognising the signs of men- tal illness, understanding their significance and tak- ing appropriate action (21). Frequent contact with individuals with intellectual disabilities across a range of settings enables carers to build up a compre- hensive knowledge of the behavioral repertoires of the individuals they support. Carers therefore have a unique insight into the behaviors of individuals, and they are ideally placed to detect any changes, which may signify the onset of mental illness. Furthermore, they are often the sole source of information, and they form an essential bridge between individuals with intellectual disabilities, their family, other staff and the mental health team.

The most basic and vital role of carers within this context is the awareness that a person with intellec- tual disabilities may suffer from a mental illness. They must also know what changes in behavior and emotional state indicate mental illness, and they need to look for patterns of change because a single feature can have several causes. Awareness of the vul- nerability factors predisposing individuals with in- tellectual disabilities to developing mental illness is also necessary. This enables carers to be proactive and to be alert to particular behavior changes before problems become chronic (68). They must also know when and how to access appropriate external opinion and support. Carers play a central role in the diagnostic process, especially for people with more severe intellectual disabilities, where assessment is heavily reliant upon third party reports and observa- tions. They must accurately describe the changes ob-

served and provide information about the person’s life such as where they live and their current relation- ships. Carers also play an important role in treat- ment implementation and monitoring. Again, they must have an understanding of which behaviors are pertinent to mental health assessment, so that they can provide feedback to mental health professionals about the effectiveness of any treatments imple- mented. However, many of the difficulties relating to the assessment of mental health problems in individ- uals with intellectual disabilities also confound the process of identification and referral.

To summarize, carers play a central role in recog- nising possible mental illness, making referrals for further psychiatric assessment and providing diag- nostic information and treatment feedback. Re- search suggests that carers lack the necessary skills to perform this role and unless conspicuous, the signs of mental health problems are likely to be overlooked by carers (10, 11). Training initiatives aimed at in- creasing the ability of carers to recognise the signs of mental illness and to make informed referral deci- sions are therefore paramount in ensuring adequate access to mental health services by individuals with intellectual disabilities (69).

Conclusions

Methodological diversity, along with complexities in defining mental illness and the nature of psychiatric assessment make conclusions about the prevalence and manifestations of mental health problems in this population are problematic and probably premature (32). Until we are able to examine more representa- tive samples, are able to assume that diagnostic dis- orders are valid and that all individuals with mental health problems have been identified, then preva- lence estimates reflect the characteristics of the ser- vice-delivery systems as much as those of individuals with intellectual disabilities and mental health prob- lems (30).

Nevertheless, the presence of mental health prob- lems in a high proportion of individuals with intel- lectual disabilities indicates the importance of providing effective support and treatment strategies for addressing mental health needs. This has impli- cations for the characteristics of residential, day and mental health services if mental health problems are

248 ASSESSMENT OF MENTAL HEALTH PROBLEMS IN PEOPLE WITH INTELLECTUAL DISABILITIES

to be adequately met. Application of standard psy- chiatric diagnostic criteria across the spectrum of in- tellectual disability is problematic, and a comprehensive, problem-based approach conducted by multidisciplinary teams is required. Ensuring that carers have adequate skills in relation to recognising and referring individuals with mental health prob- lems is essential in determining access to mental health services and in maximizing the quality of care for individuals with intellectual disabilities.

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