article critique

Randomized, Controlled Trial of an Intervention for ToddlersWith Autism: The Early Start DenverModel

WHAT’SKNOWNONTHISSUBJECT: Previous studies on the efficacy of early behavioral intervention for improving outcomes for preschool-aged childrenwith autismhave yieldedpromising results. However, no randomized clinical trials of early developmental behavioral intervention designed for toddlerswith autismhavebeen conducted to date.

WHATTHISSTUDYADDS: This study assessed the efficacy of the Early Start DenverModel, a comprehensive developmental behavioral intervention, for improving outcomesof toddlerswith ASD. The intervention,whichwas initiatedwhen childrenwere less than 21⁄2 years, resulted in significant improvements in IQ, language, adaptive behavior, andautismdiagnosis.

abstract OBJECTIVE: To conduct a randomized, controlled trial to evaluate the efficacy of the Early Start DenverModel (ESDM), a comprehensive de- velopmental behavioral intervention, for improving outcomes of tod- dlers diagnosedwith autismspectrumdisorder (ASD).

METHODS: Forty-eight children diagnosed with ASD between 18 and 30 monthsof agewere randomly assigned to 1of 2 groups: (1) ESDM inter- vention,which isbasedondevelopmentalandappliedbehavioralanalytic principlesanddeliveredby trained therapistsandparents for2years;or (2)referraltocommunityprovidersforinterventioncommonlyavailablein thecommunity.

RESULTS: Comparedwithchildrenwhoreceivedcommunity-intervention, childrenwhoreceivedESDMshowedsignificantimprovementsinIQ,adap- tivebehavior,andautismdiagnosis.Twoyearsafterenteringintervention, theESDMgrouponaverageimproved17.6standardscorepoints(1SD:15 points)comparedwith7.0pointsinthecomparisongrouprelativetobase- linescores.TheESDMgroupmaintaineditsrateofgrowthinadaptivebehav- iorcomparedwithanormativesampleoftypicallydevelopingchildren.Incon- trast, over the2-yearspan, thecomparisongroupshowedgreaterdelays in adaptivebehavior.ChildrenwhoreceivedESDMalsoweremorelikelytoexpe- rienceachange indiagnosis fromautismtopervasivedevelopmentaldisor- der,nototherwisespecified,thanthecomparisongroup.

CONCLUSIONS: This is thefirst randomized, controlled trial todemon- strate theefficacyofacomprehensivedevelopmentalbehavioral inter- vention for toddlers with ASD for improving cognitive and adaptive behavior and reducing severity of ASDdiagnosis. Results of this study underscore the importance of early detection of and intervention in autism.Pediatrics 2010;125:e17–e23

AUTHORS: GeraldineDawson, PhD,a,b,c Sally Rogers, PhD,d JeffreyMunson, PhD,e,fMilani Smith, PhD,e Jamie Winter, PhD,e JessicaGreenson, PhD,e AmyDonaldson, PhD,g and Jennifer Varley,MSe

aAutismSpeaks; bDepartment of Psychiatry, University of North Carolina, Chapel Hill, North Carolina; cDepartment of Psychology, eUniversity ofWashington AutismCenter, Center onHuman Development andDisability, and fDepartment of Psychiatry and Behavioral Sciences, University ofWashington, Seattle, Washington; dMIND Institute, Department of Psychiatry, University of CaliforniaDavis, Sacramento, California; and gDepartment of SpeechandHearingScience, PortlandState University, Portland, Oregon

KEYWORDS autism, behavioral intervention, cognitive function, developmental outcomes, early intervention

ABBREVIATIONS ASD—autismspectrumdisorder ESDM—Early Start DenverModel ABA—applied behavior analysis A/M—assess andmonitor PDD—pervasive developmental disorder NOS—not otherwise specified MSEL—Mullen Scales of Early Learning ADOS—AutismDiagnostic Observation Schedule VABS—VinelandAdaptive Behavior Scales RBS—Repetitive Behavior Scale

This trial has been registered atwww.clinicaltrials.gov (identifierNCT00090415).

www.pediatrics.org/cgi/doi/10.1542/peds.2009-0958

doi:10.1542/peds.2009-0958

Accepted for publication Jul 17, 2009

Address correspondence toGeraldineDawson, PhD, Autism Speaks, 4120Bioinformatics Building, University of North Carolina, Chapel Hill, North Carolina. E-mail: gdawson@ autismspeaks.org

PEDIATRICS (ISSNNumbers: Print, 0031-4005; Online, 1098-4275).

Copyright©2009by the American Academyof Pediatrics

FINANCIALDISCLOSURE:Sally Rogers andGeraldineDawson areauthors of Early Start DenverModel for YoungChildrenwith Autism fromwhich they receive royalties.

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Autism spectrum disorder (ASD) is characterized by impairments in so- cial reciprocity and communication, and stereotyped and repetitive behav- iors, with onset during early child- hood. Intellectual disability is present in a large proportion of individuals.1

Withaprevalenceof1per150,2autism costs the United States $35 billion per year.3 The lifetime per-capita societal cost of autism is $3.2million,with lost productivity andadult careamong the largest costs.4 Thus, early-intervention methods that can improve outcome for individuals with ASD are of high importance.

The 1987 report by Lovaas5 of an early behavioral intervention that resulted in 49% of children in the study being mainstreamed into regular class- rooms and showing significant IQ gains created a groundswell of inter- est among parents and professionals in early intervention and raised ques- tions about early plasticity in children with autism.6 Although subsequent in- tervention studies, including a ran- domized, controlled trial,7 have docu- mented improvements in IQ for a subgroup of children, questions re- garding the efficacy of early interven- tion have remained. Many of the stud- ies lackedmethodologicrigor.Authors of a recent meta-analysis of the effi- cacy of early behavioral intervention argued that stronger evidence that early behavioral intervention results inbetteroutcomesthanstandardcare is still needed.8

Our study was a randomized, con- trolled trial of early intensive behav- ioral intervention for young children with ASD that was funded by the Na- tional Institute of Mental Health (Dr Dawson, principal investigator). Itwas hypothesized that the early interven- tion would result in significant im- provements in cognitive abilities of youngchildrenwithASD. Thestudydif- fered from previous ones in several

ways. First,wemaintainedahigh level of methodologic rigor, including gold- standard diagnostic criteria, random- ization, comprehensive outcomemea- sures conducted by naive examiners, high retention rates, andmeasures of fidelityof implementationofamanual- ized intervention.

Second, toourknowledge,ourstudy is thefirstrandomized,controlledtrialof intervention for toddlers with autism; all children were younger than 30 months at entry. Given the recent rec- ommendation by the American Acad- emy of Pediatrics that 18-month-old childrenbescreened forASD,9 it is im- perative that the efficacy of early- intervention models appropriate for toddlerswith ASDbedemonstrated.

Third, the intervention, the Early Start DenverModel (ESDM),10 isacomprehen- sive early behavioral intervention for in- fants to preschool-aged children with ASD that integrates applied behavior analysis (ABA) with developmental and relationship-based approaches. The ESDM was designed to address the needs of toddlerswith ASDas youngas 12months. The intervention is provided in a toddler’s natural environment (the home)and isdeliveredbytrainedthera- pistsandparents. Inourstudy, children receivedstructured interventionathigh intensity, consistent with the National ResearchCouncil’s recommendation.11

PATIENTS ANDMETHODS

Study Procedures

Forty-eightchildrenbetween18and30 months of age diagnosedwith autistic disorder or pervasive developmental disorder (PDD), not otherwise speci- fied (NOS),were randomlyassigned to 1 of 2 groups: (1) the ESDM group re- ceived yearly assessments, 20 hours/ week of the ESDM intervention from University of Washington clinicians, parent training, and parent delivery for 5 ormore hours/week of ESDM, in addition to whatever community ser-

vices the parents chose; and (2) the assess-and-monitor (A/M) group re- ceived yearly assessments with inter- vention recommendations and refer- rals for intervention from commonly available community providers in the greater Seattle region.

Children were evaluated by experi- enced examinersnaive to intervention status at baseline (preintervention), 1 year after onset of the intervention, andateither2 yearsafteronsetof the intervention or at 48 months of age, whicheveryieldedalongertimeframe.

Participants

Participants were recruited through pediatricpractices,Birth toThreecen- ters, preschools, hospitals, and state and local autism organizations. Exclu- sioncriteria included(1)aneurodevel- opmental disorder of known etiology (eg, fragileXsyndrome),(2)significant sensory ormotor impairment, (3)ma- jor physical problems such as a chronic serious health condition, (4) seizuresattimeofentry, (5)useofpsy- choactivemedications, (6) history of a serious head injury and/or neurologic disease, (7) alcohol or drug exposure during theprenatal period, and (8) ra- tio IQ below 35 asmeasured bymean age equivalence score/chronological age on the visual reception and fine motor subscales of the Mullen Scales of Early Learning (MSEL).12 Children who developed seizures during the courseof thestudywerenotexcluded. Inclusion criteria included age below 30 months at entry, meeting criteria forautisticdisorderontheToddlerAu- tism Diagnostic Interview,13 meeting criteria for autism or ASD on the Au- tism Diagnostic Observation Sched- ule,14 andaclinicaldiagnosisbasedon Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria15 using all available information, residing within 30 min- utes of the University of Washington,

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andwillingness toparticipate ina �2- year intervention. At baseline, 18 chil- dren in the A/M group and 21 in the ESDMgroupreceivedaDSM-IVdiagno- sis of autistic disorder. Six children in theA/Mgroupand3intheESDMgroup received a diagnosis of PDD NOS. This differencewasnotsignificant(Fisher’s exact test, P � .231). The ethnicities involved were Asian (12.5%), white (72.9%), Latino (12.5%), and multira- cial (14.6%). The male-to-female ratio reflected the expected ratio in ASD of 3.5:1.

Retention rates were 100% (1-year) and100%(2-year) for the ESDMgroup and96% (1-year) and 88% (2-year) for theA/Mgroup,whichyieldedasample sizeof24 intheESDMand21intheA/M group at outcome. Figure 1 shows the participant flowchart.

Measures

AutismDiagnostic Interview–Revised

The toddlerversionof theAutismDiag- nostic Interview–Revised13 is a semi- structured parent interview that as- sesses autism symptoms across 3 domains: social relatedness; commu- nication; and repetitive, restricted behaviors.

AutismDiagnostic Observation Schedule

The Autism Diagnostic Observation Schedule (ADOS), WPS version,14 is a semistructuredstandardizedobserva- tion that measures autism symptoms in social relatedness, communication, play, and repetitive behaviors. A stan- dardized severity score based on codeswithinthesedomainscanbecal- culated to compare autism symptoms acrossmodules.16

Mullen Scales of Early Learning (MSEL)

TheMSEL12 are a standardized develop- mental test forchildren frombirth to68 months of age. Four of the 5 subscales

wereadministered:finemotor,visualre- ception,expressivelanguage,andrecep- tive language. T scores for subscales have a mean of 50 (SD: 10). The early- learning composite score is a standard scorewithmeanof100(SD:15).

VinelandAdaptive Behavior Scales

TheVinelandAdaptiveBehaviorScales (VABS)17areaparent interviewthatas- sesses social, communication, motor, anddaily livingskills.Theyprovideage- equivalent and standard scores for several subscales, including expres- siveandreceptive languageandsocial adaptive functioning.

Repetitive Behavior Scale

The Repetitive Behavior Scale (RBS)18

is a parent questionnaire that charac- terizes theseverityof repetitivebehav- iors, yielding 6 subdomain scores (eg,

sameness, self-injurious behavior) anda total score.

Randomization

Participants were stratified into 2 groupson thebasis of composite IQat entry (�55 and 55) and gender to en- sure comparable IQ andgender ratios between groups. Within each of these strata, randomization was conducted byusingrandompermutedblocksof4. The intervention groups did not differ at baseline in severity of autismsymp- toms based on ADOS scores, chrono- logical age, IQ, gender, or adaptive be- haviors (see Table 1).

InterventionGroups

ESDMGroup

The ESDMgroupwasprovidedwith in- tervention by trained therapists for

Assessed for eligibility (n = 96)

Excluded (n = 45) Did not meet diagnostic criteria (n = 38) Met diagnostic criteria but declined to participate in randomization because of

demands of intervention (n = 7)

Randomly assigned (n = 51)

Allocated to ESDM group (n = 24)

Allocated to A/M group (n = 24)

Time 1 assessment (n = 23)

Followed (n = 23) Lost to follow-up (n = 1)

Time 2 assessment (n = 24)

Followed (n = 24) Lost to follow-up (n = 0)

Time 2 assessment (n = 21)

Followed (n = 21) Lost to follow-up (n = 3)

Time 1 assessment (n = 24)

Followed (n = 24) Lost to follow-up (n = 0)

Analyzed (n = 21)Analyzed (n = 24)

Excluded (n = 3) Declined ESDM because of intervention requirements (n = 2)

Subsequently diagnosed with Rett syndrome (n = 1)

E nr

ol lm

en t

A llo

ca tio

n Fo

llo w

-u p

A na

ly si

s

FIGURE 1 Participant flowchart.

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2-hoursessions, twiceperday, 5days/ week, for 2 years. A detailed interven- tion manual and curriculum were used.19 One or both parentswere pro- videdwithparenttrainingfromthepri- mary therapist during semimonthly meetings, duringwhich the principles and specific techniques of ESDMwere taught. Parents were asked to use ESDMstrategiesduringdaily activities and to keep track of the number of hours during which they used these strategies. ESDMuses teachingstrate- gies that involve interpersonal ex- change and positive affect, shared en- gagement with real-life materials and activities,adultresponsivityandsensi- tivity tochildcues,and focusonverbal and nonverbal communication, based onadevelopmentally informedcurric- ulumthataddressesalldevelopmental domains. Teaching strategies are con- sistentwith theprinciplesofABA,such as the use of operant conditioning, shaping, and chaining. Each child’s plan is individualized.There isastrong parent-family role responsive to each family’s unique characteristics. Par- entsare taught thebasic ESDMstrate- gies and asked to use themduring ev- eryday activities such as feeding, bath time,andplay. Parentschose teaching

objectives from the curriculum that they viewedashighpriority.

Intervention programs were super- vised by a graduate-level, trained lead therapist who had a minimum of 5 years’ experience providing early in- tervention to young children with au- tism,withongoingconsultation froma clinical psychologist, speech-language pathologist, anddevelopmentalbehav- ioral pediatrician. An occupational therapist provided consultation as needed. Intervention objectives and strategies were reviewed, and the in- tervention was observed at least bi- weekly by the lead therapist andevery 3 months by the speech-language pa- thologist. Intervention was delivered by therapistswho typically held abac- calaureate degree, received 2months of training by the lead therapist, and met weekly with the lead therapist. Therapists were trained to compe- tence, defined as completing course- work, passing tests, mastering the in- tervention, demonstrating fidelity of 85%ofmaximumscoreson thefidelity instrument, and maintaining ongoing fidelity.20

ESDM intervention hours were sys- tematically recorded. Although 20

therapist-delivered interventionhours perweekweremadeavailable, theac- tualmeanwas15.2 hours (SD: 1.4) be- cause of illnesses, vacations, and so on. Parents reported spending an av- erage of 16.3 hours/week (SD: 6.2) us- ing ESDM strategies. The ESDM group reportedanaverageof5.2hours/week (SD:2.1) inother therapies(eg,speech therapy, developmental preschool) over the study enrollment period. Other therapies were documented by usingan interventionhistory interview administered every 6months.

A/MGroup

Childrenwhowererandomlyassigned to theA/Mgroupreceivedcomprehen- sive diagnostic evaluations, interven- tion recommendations, and commu- nity referrals at baseline and again at each of the 2 follow-up assessments. Familiesweregivenresourcemanuals and readingmaterials at baseline and twice yearly throughout the study. The A/M group reported an average of 9.1 hours of individual therapy and an averageof9.3hours/weekofgroup in- terventions (eg, developmental pre- school) across the 2-year period dur- ing which the intervention study was conducted. In thegreaterSeattlearea, there are a number of Birth to Three centers that provide interventions, speech and language therapy, and occupational therapy. Developmen- tal preschool programs vary but typ- ically include special education and relatedservices. Thereareanumber of private ABA providers in the community.

Data Analysis

TheeffectofESDMinterventionwasas- sessed by using repeated-measures analysis of variance,with apriori con- trasts that compared baseline scores with1-and2-yearoutcomescores.The primary outcome measures were the MSEL composite standard score and the VABS composite standard score.

TABLE1 BaselineMeasures for ESDMandA/MGroups

A/MGroup ESDMGroup F MS P

Mean SD N Mean SD N

Age at study entry,mo 23.1 3.9 24 23.9 4.0 24 0.48 7.52 .490 MSEL Early-learning compositea 59.4 8.6 24 61.0 9.2 24 0.40 31.69 .530 Receptive languageb 21.2 3.8 24 21.1 4.7 24 0.01 0.19 .920 Expressive languageb 26.0 8.6 24 24.5 7.2 24 0.48 30.08 .492 Visual receptionb 30.8 8.9 24 33.2 11.0 24 0.70 70.08 .406 Finemotorb 30.6 10.7 24 33.9 11.9 24 1.02 130.02 .318 VABS Adaptive behavior compositea 69.9 7.3 24 69.5 5.7 24 0.04 1.69 .844 Communicationa 69.6 7.3 24 68.4 7.6 24 0.32 17.52 .577 Socializationa 72.4 9.4 24 73.8 7.7 24 0.29 21.33 .594 Daily living skillsa 86.8 10.0 24 87.3 11.4 24 0.03 3.52 .381 Motor skillsa 72.5 6.5 24 70.9 6.2 24 0.78 31.69 .862 ADOS severity score 6.9 1.7 24 7.2 1.7 24 0.35 1.02 .557 RBS total 21.5 19.2 24 15.2 10.8 24 1.93 468.75 .171

No significant differences amongbaselinemeasureswere found (P � .10 on allmeasures). aStandard score (mean: 100 �SD: 15�). b T score (mean: 50 �SD: 10�).

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Secondary outcome measures were the ADOS severity score,16 the RBS,18

MSEL, and VABS subscale scores, and changes in diagnostic status (autistic disorder, PDDNOS, andnodiagnosis).

RESULTS

No serious adverse effects related to the interventionwere reportedduring the 2-year period.

1-Year Outcome

Table 2 displays statistics for 1- and 2-year outcomes, change scores rela- tive to baseline, and group compari- sons for primary and secondarymea- sures. Significant intervention effects were found for cognitive ability after 1 year on theMSEL composite standard scores.TheESDMgroupdemonstrated an average IQ increase of 15.4 points (�1SD)comparedwithan increaseof 4.4 points in theA/Mgroup. The visual receptionsubscalewas theonly indi- vidual subscale on the MSEL on which the groups significantly dif- fered at the 1-year outcome. The ESDM group gained 5.6 T-score points, whereas the A/M group de- clined1.7points. TheESDMgroup im- proved 17.8 points on receptive lan- guage compared with a 9.8-point

improvement in the A/Mgroup, a dif- ference that fell just short of statis- tical significance.

As a whole, children gained raw score points in the daily living skills subscale of the VABS; however, progress was much slower in rela- tion to the VABS normative sample between baseline and 1 year. The groups did not differ in terms of adaptive behavior, measured by the VABS composite standard score, af- ter 1 year (the ESDMgroupshoweda 3.8-point decline, and the A/M group showed a 6.3-point decline). The groupsdidnotdiffer in termsof their ADOS severity scores or RBS total score after 1 year of intervention.

2-Year Outcome

Two years after the baseline assess- ment, theESDMgroupshowedsignif- icantly improved cognitive ability, measured by MSEL composite stan- dard scores, which increased 17.6 points compared with 7.0 points in the A/M group. The bulk of this change seems to have been a result of receptive and expressive lan- guage, which showed increases of 18.9 and12.1points, respectively, for

the ESDM group, whereas the A/M group improved 10.2 and 4.0 points, respectively.

The ESDM and A/M groups signifi- cantly differed in terms of their adaptive behavior as measured by the VABS composite standard scores at the2-yearoutcome(seeFig2). The ESDM group showed similar stan- dard scores at the 1- and 2-year out- comes, indicatingasteadyrateofde- velopment, whereas the A/M group, on average, showed an 11.2-point av- erage decline. Thus, the A/M group’s delays in overall adaptive behavior became greater when compared with the normative sample. The A/M group showed average declines in standard scores that were twice as great as those in the ESDM group in thedomainsofsocialization,daily liv- ing skills, and motor skills. The groupsdidnotdiffer in termsof their ADOS severity scores or RBS total score after 2 years of intervention.

Diagnosis

At baseline, the diagnoses in each group were not significantly differ- ent (Fisher’s exact test, P � .461) and were distributed as follows:

TABLE2 Child OutcomesAfter 1 and 2 Years of Study Participation

1-y Outcome 2-y Outcome Group � Time (Baseline vs 1-y)

Group � Time (Baseline vs 2-y)

A/M (N � 23) ESDM(N � 24) A/M (N � 21) ESDM(N � 24)

Mean SD � Mean SD � Mean SD � Mean SD � F MS P F MS P

Chronological age,mo 38.1 3.8 15.3 38.8 4.4 14.9 52.1 4.3 29.3 52.4 3.4 28.5 0.95 2.18 .334 1.27 6.91 .266 MSEL Early-learning composite

64.0 13.8 4.4 76.4 23.4 15.4 66.3 15.3 7.0 78.6 24.2 17.6 5.99 1416.90 .018 4.31 1264.38 .044

Receptive language 31.1 11.1 9.8 38.9 15.4 17.8 31.5 10.6 10.2 40.0 16.3 18.9 4.00 745.21 .051 4.14 843.56 .048 Expressive language 33.0 11.5 6.7 36.1 14.2 11.6 30.0 9.2 4.0 36.6 13.6 12.1 1.99 290.43 .165 4.88 748.07 .033 Visual reception 29.0 10.7 �1.7 38.8 16.4 5.6 34.5 13.0 4.5 41.0 17.9 7.8 4.22 621.97 .046 0.63 126.23 .433 Finemotor 26.1 8.6 �5.0 32.7 11.7 �1.3 28.5 9.5 �2.8 33.5 12.2 �0.4 1.32 161.35 .256 0.46 63.81 .503 VABS 63.7 8.8 �6.3 65.7 9.8 �3.8 59.1 8.8 �11.2 68.7 15.9 �0.8 0.85 71.61 .360 7.05 1181.82 .011 Communication 71.0 13.0 1.2 73.5 11.7 5.0 69.4 15.8 �0.7 82.1 21.8 13.7 1.38 175.69 .246 6.38 2300.98 .015 Socialization 68.9 12.1 �3.5 70.0 9.9 �3.8 63.1 9.3 �8.9 69.2 11.6 �4.6 0.01 1.15 .934 1.29 204.57 .263 Daily living skills 65.3 7.1 �7.4 65.6 8.6 �5.3 58.0 8.1 �14.5 64.7 12.4 �6.2 0.89 51.78 .350 6.73 773.34 .013 Motor skills 70.7 12.2 �15.9 75.1 14.4 �12.2 64.1 12.3 �23.1 77.4 19.8 �9.9 0.99 157.43 .326 7.40 1881.65 .009 ADOS severity score 7.3 2.1 0.4 6.5 1.5 �0.7 7.3 1.8 0.3 7.0 1.9 �0.2 3.38 13.15 .072 0.66 3.29 .422 RBS total 23.3 17.5 1.0 15.5 12.3 0.9 22.0 16.3 �0.6 16.7 13.1 2.5 0.001 0.19 .976 0.37 92.50 .545

� indicatesmean change frombaseline.

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ESDM,21withautisticdisorderand3 with PDD NOS; A/M, 18 with autistic disorder and 6 with PDD NOS. At the 2-year outcome, 15 (62.5%) children in the ESDM group had the same di- agnosis (14 with autistic disorder, 1 with PDD NOS) and 15 (71.4%) chil- dren in the A/M group had the same diagnosis (all 15 with autistic disor- der). Diagnosis improved (baseline autistic disorder to PDD NOS at year 2) for 7 (29.2%) children in the ESDM group but for only 1 (4.8%) child in the A/M group. However, the diagno- sis changed from PDD NOS at base- line to autistic disorder at year 2 for 2 (8.3%) children in the ESDM group and 5 (23.8%) children in the A/M group. Thus, children who received ESDM were significantly more likely to have improved diagnostic status at the2-yearoutcomecomparedwith children in the A/M group, as as- sessed by using Fisher’s exact test 2 (interventiongroups) � 2 (improved versus worsened diagnosis) contin- gency table (P � .041). Fisher’s exact test for the 2 (intervention groups) � 3 (diagnostic change: no change versus improved versus worsened diagnosis) contingency table was just short of significance (P � .060).

DISCUSSION

Recommendations by the American Academy of Pediatrics9 that all chil- dren be screened for autism at 18 months of age oblige the develop- mentof interventions thatareappro- priate for toddlers with ASD. To our knowledge, this study is the first to demonstrate the efficacy of an inten- sive intervention designed for tod- dlers with ASD as young as 12 months of age. After 2 years of inter- vention, children provided with the ESDM19 showed significant improve- ments in IQ, adaptive behavior, and diagnostic status compared with childrenwhoreceivedcommunity in- terventions. Consistent evidence of improvement in communicative abil- ities in theESDMgroupwas found,as demonstrated by gains in receptive and expressive language scores on the MSEL subscales and the VABS communication subscale. Significant improvement for the ESDM group was found for overall adaptive be- havior, communication, daily living skills, and motor skills. Specifically, the ESDMgroup, althoughstill signif- icantly delayed in adaptive behavior, was able to keep pace with the rate of change of the VABS normative

sample, whereas the community- based intervention group continued to fall farther behind in adaptive be- havior. Given the importance of adaptive behavior for everyday func- tioning at home and school, the fact that theESDMgroupdidnot continue to fall farther behind is likely to af- fect ability to function in less- restrictive environments. This dem- onstrates that the ESDM intervention acceleratesoverall developmentand is generalizing to everyday life. Whereas 71% of the children in the group that received community- based intervention retained their di- agnosis of autistic disorder over the 2-yearperiod, only 56%of children in theESDMgroupdidso. Thediagnosis of 7 children (30%) in the ESDM group changed from autistic dis- order to PDD NOS, whereas this only occurred for 1 child (5%) in the community-intervention group. These diagnostic assessments were conducted by experienced clinicians who were naive with respect to intervention-group status. However, this change in diagnostic severity was not reflected in significant dif- ferences in theADOSseverity scores. This lack of correspondence be- tween measures is difficult to inter- pret, because the child’s perfor- mance in the ADOS contributes to clinical diagnosis. However, other behaviors, includingparental report, also contribute to overall clinical diagnosis. The repetitive-behavior scores also did not changeover time in either group.

CONCLUSIONS

The outcomes of this study, which in- volve an increase in IQ scores of 17 points(�1SD)andsignificantgains in language and adaptive behavior, com- pare favorably with other controlled studies of intensive early intervention (eg, Smith et al [2000],7 which deliv- ereddiscrete trial intervention for �2

FIGURE 2 Mean scores on the MSEL (left) and the VABS composite (right) for children in the ESDM and A/M groups 1 and2 years after entering study. Error bars indicate 1SD.

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years for 25–40 hours/week). The group differences reported from our study are larger than those produced byothercomparative trialsofdevelop- mental behavioral approaches, which were conducted for briefer periods of time andwith fewer hours of delivery perweek.21,22Whether thechildrenwill sustain their gains over a longer term is an important question that will re- quire follow-up study.

The results of this study suggest that the ESDMmodel,19 an intervention ap- proach that uses teaching strategies of ABA that are deliveredwithin an af- fectively rich, relationship-focused context, canbeeffective for improving outcomes of young children with au- tism. Parents’ use of these strategies at home during their daily activities likely was an important ingredient of its success.

ACKNOWLEDGMENTS This study was supported by National Institute of Mental Health grant U54MH066399 (toDrDawson).

We acknowledge the contributions of the parents and children who took part in this study and the support and effortofnumerousundergraduateand graduate students and staff who are part of the University of Washington AutismCenter.

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