Developing the Diagnostic Interview for Adolescents and Adults with Mild/Moderate Intellectual Disabilities: An interview schedule of mental disorders (DIAAID).

Introduction: Young people with intellectual disabilities (ID) are at an increased risk for experiencing mental health issues compared to their peers without disabilities. Further, there are limited resources available to help accurately assess mental health disorders and that are accessible for adolescents with ID. Method: This paper describes the iterative development and pilot testing of the Diagnostic Interview for Adolescents and Adults with Intellectual Disabilities (DIAAID). The authors utilized Evidence Center Design and Universal Design principals to develop the DIAAID; a multi-informant diagnostic interview. Results: The DIAAID development resulted in the creation of 15 adolescents disorder interviews and 24 caregiver disorder interviews. Preliminary results suggest that the DIAAID is a feasible and accessible diagnostic interview for adolescents with ID and their caregivers. Discussion: Lessons learned from DIAAID implementation and future areas research are discussed.

Brief report: replication of the psychometric characteristics of the behavioral inflexibility scale in an independent sample.

The Behavioral Inflexibility Scale (BIS) is a recently developed measure of behavioral inflexibility, defined as rigid patterns of behavior that contrast with the need to be flexible when the situation calls for it. In this study, we sought to replicate previous findings on the psychometric properties of the BIS in a community sample. Data for this study were collected using in-person assessments of 163 autistic and 95 non-autistic children ages 3-17 and included the BIS, measures of social-communication ability and repetitive behaviors, and an assessment of cognitive ability. Our findings replicate the psychometric properties of the BIS, indicating that the measure is a valid measure of behavioral inflexibility in ASD.

Examining Sensitivity to Developmental Changes on the Behavioral Inflexibility Scale.

PURPOSE: The study objective was to determine if the validated Behavioral Inflexibility Scale (BIS) is sensitive to the detection of developmental changes in inflexibility in a sample of autistic children. METHODS: Parents of autistic children (n = 146, 3-17 years) completed the BIS at two time points, one year apart, to examine change. RESULTS: The findings indicate the BIS is sensitive to the detection of developmental changes and that child-level variables are not associated with those changes. Children's Time 1 BIS scores predicted children's severity on an independent outcome measure. Finally, a relationship between total services children were receiving and change in BIS scores over time was not found. CONCLUSION: The findings suggest the BIS is a reasonable candidate for consideration as an outcome measure.

Measuring the Functional Impact of Behavioral Inflexibility in Children with Autism Using the Behavioral Inflexibility Scale: Clinical Interview (BIS-CI).

For individuals with autism spectrum disorder (ASD), behavioral inflexibility can affect multiple domains of functioning and family life. The objective of this study was to develop and validate a clinical interview version of the Behavioral Inflexibility Scale. Trained interviewers conducted interviews with parents of 144 children with ASD and 70 typically developing children (ages: 3-17 years). Using exploratory factor analysis, the Behavioral Inflexibility Scale-Clinical Interview (BIS-CI) was found to be unidimensional. Reliability data indicated the measure was internally consistent (α = 0.80), achieved excellent inter-rater reliability (ICC = 0.97) and test-retest reliability (ICC = 0.87). These findings demonstrate that the BIS-CI is a reliable and valid measure to determine the functional impact of behavioral inflexibility.

Putting "ME" into measurement: Adapting self-report health measures for use with individuals with intellectual disability.

BACKGROUND: Self-report is important for measuring health outcomes; however, most research in intellectual disability (ID) relies on proxy report. The lack of cognitively accessible measures is one barrier to accurate self-reporting by individuals with ID. AIMS: This paper describes the process of adapting self-report measures of health status, health-related quality of life, and environment for use by individuals with ID and presents evidence on their usability (accessibility), usefulness (independent self-report), and reliability (internal consistency and test-retest). METHODS AND PROCEDURES: We used an inclusive research approach, in which we collaborated with adults with ID to revise, cognitively test, and pilot test cognitively accessible self-report measures. Technology supported the independent completion of measures. We assessed usability, usefulness, and reliability of these measures in 41 adults with ID. OUTCOMES AND RESULTS: The resulting measures are useful (independently completed) and usable (elicit a range of responses), with modest reliability (internal consistency and test-retest). CONCLUSIONS AND IMPLICATIONS: Self- report by adults with ID is feasible. A key element of this measure adaptation process was engaging adults with ID. More research is needed to understand the reliability and validity of the adapted measures and the characteristics of the population for whom they are most usable.

Reliability and validity of the Pediatric Anxiety Rating Scale modified for autism spectrum disorder.

LAY ABSTRACT: Many youth with autism spectrum disorder have anxiety, but it can be difficult to assess anxiety with existing measures. We modified the Pediatric Anxiety Rating Scale for youth with autism spectrum disorder and tested the new measure in a group of 116 youth (age: 5-17 years) with autism spectrum disorder. The Pediatric Anxiety Rating Scale for youth with autism spectrum disorder is an interview that a clinician usually completes with the child and parent together. We modified the interview questions and scoring instructions based on feedback from parents of children with autism spectrum disorder and from a panel of experts in autism spectrum disorder and anxiety. Unlike many other anxiety measures, the Pediatric Anxiety Rating Scale for youth with autism spectrum disorder relies less on a child's verbal expression of anxiety and more on signs that a parent can easily observe. Training clinicians to administer and score the Pediatric Anxiety Rating Scale for youth with autism spectrum disorder was uncomplicated, and raters showed excellent agreement on video-recorded interviews. Youth who were not currently in treatment for anxiety had stable Pediatric Anxiety Rating Scale for youth with autism spectrum disorder scores with repeat measurement over a 1-month period. The Pediatric Anxiety Rating Scale for youth with autism spectrum disorder is a useful clinician-rated measure of anxiety in youth with autism spectrum disorder and fills a gap for assessing anxiety in this population.

Probiotics for Gastrointestinal Symptoms and Quality of Life in Autism: A Placebo-Controlled Pilot Trial.

Objective: A randomized pilot trial of gastrointestinal (GI) symptoms targeting probiotic for quality of life in autism spectrum disorder (ASD). Methods: Thirteen children, 3-12 years of age with ASD, anxiety, and GI symptoms, were randomized into a probiotic crossover trial of 8 weeks each on VISBIOME and placebo separated by a 3-week washout. VISBIOME contains eight probiotic species, mostly Lactobacillus and Bifidobacterium. Primary outcome was the Pediatric Quality of Life Inventory (PedsQL) GI module. Secondary outcomes included gut microbiota analysis, the Parent-Rated Anxiety Scale for ASD (PRAS-ASD), and parent-selected target symptoms. A mixed analysis model was applied. Results: Thirteen children were randomized, with 10 completing the study (77% retention): 6 in probiotic/placebo sequence, 4 in placebo/probiotic sequence. Adherence to study treatment was 96%. There were no serious adverse events (AEs), and more nonserious AEs occurred with placebo than with probiotic, including those attributable to treatment. Only 6 of the 10 guessed the correct treatment at the end of week 8. Over the 19-week trial, each outcome improved from baseline and PedsQL correlated significantly with abundance of Lactobacillus without discernable changes to microbiota composition/diversity. Although probiotic showed more improvement than placebo, PedsQL and PRAS-ASD were not statistically significant, as expected at this sample size. PedsQL effect size was d = 0.49 by the general model and d = 0.79 by simple comparison of week 8 changes. A parent-selected target symptom showed significant improvement in GI complaints on probiotic compared with placebo (p = 0.02, d = 0.79). Probiotic effects carried over through the 3-week washout. Conclusion: The VISBIOME formulation was safe and suggested a health benefit in children with ASD and GI symptoms who retained Lactobacillus. The moderate effect size compared with placebo warrants a larger trial using a parallel-group design.

Treatment of inattention, overactivity, and impulsiveness in autism spectrum disorders.

We reviewed the recent literature on medicines used to manage inattention, impulsiveness, and overactivity in children with pervasive developmental disorders (autistic disorder, pervasive developmental disorder not otherwise specified, Asperger's disorder) using computer searches of pharmacologic studies. A substantial number of reports were identified and summarized. The literature tends to be dominated by uncontrolled studies, although the number of controlled trials is growing. Findings are described for psychostimulants, noradrenergic reuptake inhibitors, antipsychotics, alpha adrenergic agonists, antidepressants, anxiolytics, cholinesterase inhibitors, N-methyl-D-aspartate receptor blockers, and antiepileptic mood stabilizers. Evidence for a positive effect is strongest for psychostimulants, noradrenergic reuptake inhibitors, antipsychotics, and alpha adrenergic agonists. Evidence for efficacy seems weakest for newer antidepressants, anxiolytics, and mood stabilizers.

Vestibular Stimulation for ADHD: randomized controlled trial of Comprehensive Motion Apparatus.

OBJECTIVE: This research evaluates effects of vestibular stimulation by Comprehensive Motion Apparatus (CMA) in ADHD. METHOD: Children ages 6 to 12 (48 boys, 5 girls) with ADHD were randomized to thrice-weekly 30-min treatments for 12 weeks with CMA, stimulating otoliths and semicircular canals, or a single-blind control of equal duration and intensity, each treatment followed by a 20-min typing tutorial. RESULTS: In intent-to-treat analysis (n = 50), primary outcome improved significantly in both groups (p = .0001, d = 1.09 to 1.30), but treatment difference not significant (p = .7). Control children regressed by follow-up (difference p = .034, d = 0.65), but overall difference was not significant (p = .13, d = .47). No measure showed significant treatment differences at treatment end, but one did at follow-up. Children with IQ-achievement discrepancy > or = 1 SD showed significantly more CMA advantage on three measures. CONCLUSION: This study illustrates the importance of a credible control condition of equal duration and intensity in trials of novel treatments. CMA treatment cannot be recommended for combined-type ADHD without learning disorder.

Testing genetic modifiers of behavior and response to atomoxetine in autism spectrum disorder with ADHD.

BACKGROUND: Frequent non-pathogenic genetic variants may act as moderators of phenotypic severity for complex disorders such as autism spectrum disorder (ASD). We previously identified polymorphisms affecting mRNA expression of candidate genes, including tryptophan hydroxylase 2 (TPH2), dopamine beta hydroxylase (DBH), and dopamine transporter (DAT, SLC6A3). METHOD: We compare genotypes and (1) clinical response to atomoxetine, (2) scores from the Autism Diagnostic Interview-Revised (ADI-R), and (3) severity of Attention Deficit Hyperactivity Disorder (ADHD) symptoms in a cohort of patients with ASD from multiple study sites. RESULTS: There was no association between CYP2D6 metabolizer status and atomoxetine response. TPH2 rs7305115 genotype was associated with ADI-R Restrictive/Repetitive Behavior score (p=0.03). DBH rs1611115 genotype was associated with ADI-R Social score (p=0.002) and Restrictive/Repetitive Behavior score (p=0.04). The DAT intron 8 5/6 repeat was associated with ADHD symptoms (ABC Hyperactivity p=0.01 and SNAP ADHD p=0.03), replicating a previous finding. CONCLUSIONS: We find associations between ASD phenotypes and regulatory variants in catecholamine biosynthesis genes. This work may help guide future genetics studies related to ASD.

Atomoxetine, Parent Training, and Their Effects on Sleep in Youth with Autism Spectrum Disorder and Attention-Deficit/Hyperactivity Disorder.

OBJECTIVE: Sleep disturbance is often a problem for children with either autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD). Psychostimulant medications used to treat ADHD symptoms can exacerbate this problem. For children with ASD and ADHD, atomoxetine (ATX) is a viable alternative to psychostimulants. We investigated the effects of ATX and a manualized parent training (PT) program targeting noncompliance, on the sleep quality of children with ASD and ADHD. METHODS: Participants in a randomized clinical trial were treated with ATX + PT, ATX alone, PT alone, or placebo (PBO) alone, for 10 weeks. Fifty-four of 128 (42%) caregivers completed the Children's Sleep Habits Questionnaire (CSHQ) at baseline and endpoint. Analysis of covariance was used to investigate possible differences between treatment groups. RESULTS: There were no significant differences between treatment groups, including PBO on the CSHQ 33-Item total score, total hours of sleep per day, and total minutes awake after sleep onset at the study endpoint. CONCLUSION: ATX appears sleep neutral. Clinicians who treat ADHD symptoms in children and adolescents with ASD may prefer ATX over psychostimulants when sleep disturbance is an issue.

Parent Stress in a Randomized Clinical Trial of Atomoxetine and Parent Training for Children with Autism Spectrum Disorder.

We previously reported a 2 × 2 randomized clinical trial of atomoxetine (ATX) and parent training (PT) for attention deficit hyperactivity disorder (ADHD) symptoms and behavioral noncompliance in 128 children with autism spectrum disorder, ages 5-14 years. Children were randomized to one of four conditions: ATX alone, placebo alone, ATX + PT, or PT + placebo. Both ATX and PT improved some indices of ADHD and behavioral compliance. In this report, we describe parent stress over time and across conditions. All four treatments improved parent self-rated stress from baseline to week 10. However, there were no statistically significant differences between treatment groups. Significantly more improvement in parent stress scores was observed for clinical responders than non-responders. ClinicalTrials.gov Title: Atomoxetine, Placebo and Parent Management Training in Autism (Strattera) ClinicalTrials.gov Identifier: NCT00844753.

A 1.5-Year Follow-Up of Parent Training and Atomoxetine for Attention-Deficit/Hyperactivity Disorder Symptoms and Noncompliant/Disruptive Behavior in Autism.

OBJECTIVE: To examine status of children with autism spectrum disorder (ASD) 10 months after a 34-week clinical trial of atomoxetine (ATX) and parent training (PT). METHODS: In a 2 × 2 design, 128 children with ASD and attention-deficit/hyperactivity disorder (ADHD) were randomly assigned ATX, PT+placebo, PT+ATX, or placebo alone. PT was weekly for 10 weeks, and then monthly. ATX/placebo was titrated over 6 weeks [≤1.8 mg/kg/d], and then maintained until week 10. Responders continued to week 34 or nonresponse. Placebo nonresponders had a 10-week ATX open trial; ATX nonresponders were treated clinically. All continued to week 34. With no further treatment from the study, all were invited to follow-up (FU) at 1.5 years postbaseline; 94 (73%) participated. Changes from Week 34 to FU and from baseline to FU were tested by one-way analysis of variance or chi-squared test. PT versus no PT was tested by chi-squared test, Fisher's exact test, Welch's t-test, Student's t-test, and Mann-Whitney's U test. RESULTS: For the whole sample, the primary outcomes (parent-rated ADHD on the Swanson, Nolan, and Pelham [SNAP] scale and noncompliance on the Home Situations Questionnaire [HSQ]) deteriorated mildly from week 34 to FU, but were still substantially better than baseline (SNAP: t = 12.177, df = 93, p < 0.001; HSQ: t = 8.999, df = 93, p < 0.001). On the SNAP, 61% improved ≥30% from baseline (67% did at week 34); on noncompliance, 56% improved ≥30% from baseline (77% did at week 34). Outcomes with PT were not significantly better than without PT (SNAP p = 0.30; HSQ p = 0.27). Originally assigned treatment groups did not differ significantly. Only 34% still took ATX; 27% were taking stimulants; and 25% took no medication. CONCLUSIONS: The majority retained their 34-week end-of-study improvement 10 months later, even though most participants stopped ATX. For some children, ATX continuation may not be necessary for continued benefit or other drugs may be necessary. Cautious individual clinical experimentation may be justified. Twelve sessions of PT made little long-term difference. ClinicalTrials.gov Identifier: Atomoxetine, Placebo and Parent Management Training in Autism (Strattera) (NCT00844753).

Effects of Metformin on Spatial and Verbal Memory in Children with ASD and Overweight Associated with Atypical Antipsychotic Use.

OBJECTIVES: Studies in humans and rodents suggest that metformin, a medicine typically used to treat type 2 diabetes, may have beneficial effects on memory. We sought to determine whether metformin improved spatial or verbal memory in children with autism spectrum disorder (ASD) and overweight associated with atypical antipsychotic use. METHODS: We studied the effects of metformin (Riomet®) concentrate on spatial and verbal memory in 51 youth with ASD, ages 6 through 17 years, who were taking atypical antipsychotic medications, had gained significant weight, and were enrolled in a trial of metformin for weight management. Phase 1 was a 16-week, randomized, double-blind, placebo-controlled, parallel-group comparison of metformin (500-850 mg given twice a day) versus placebo. During Phase 2, all participants took open-label metformin from week 17 through week 32. We assessed spatial and verbal memory using the Neuropsychological Assessment 2nd Edition (NEPSY-II) and a modified children's verbal learning task. RESULTS: No measures differed between participants randomized to metformin versus placebo, at either 16 or 32 weeks, after adjustment for multiple comparisons. Sixteen-week change in memory for spatial location on the NEPSY-II was nominally better among participants randomized to placebo. However, patterns of treatment response across all measures revealed no systematic differences in performance, suggesting that metformin had no effect on spatial or verbal memory in these children. CONCLUSIONS: Although further study is needed to support these null effects, the overall impression is that metformin does not affect memory in overweight youth with ASD who were taking atypical antipsychotic medications.

Risperidone in children with autism and serious behavioral problems.

BACKGROUND: Atypical antipsychotic agents, which block postsynaptic dopamine and serotonin receptors, have advantages over traditional antipsychotic medications in the treatment of adults with schizophrenia and may be beneficial in children with autistic disorder who have serious behavioral disturbances. However, data on the safety and efficacy of atypical antipsychotic agents in children are limited. METHODS: We conducted a multisite, randomized, double-blind trial of risperidone as compared with placebo for the treatment of autistic disorder accompanied by severe tantrums, aggression, or self-injurious behavior in children 5 to 17 years old. The primary outcome measures were the score on the Irritability subscale of the Aberrant Behavior Checklist and the rating on the Clinical Global Impressions - Improvement (CGI-I) scale at eight weeks. RESULTS: A total of 101 children (82 boys and 19 girls; mean [+/-SD] age, 8.8+/-2.7 years) were randomly assigned to receive risperidone (49 children) or placebo (52). Treatment with risperidone for eight weeks (dose range, 0.5 to 3.5 mg per day) resulted in a 56.9 percent reduction in the Irritability score, as compared with a 14.1 percent decrease in the placebo group (P<0.001). The rate of a positive response, defined as at least a 25 percent decrease in the Irritability score and a rating of much improved or very much improved on the CGI-I scale, was 69 percent in the risperidone group (34 of 49 children had a positive response) and 12 percent in the placebo group (6 of 52, P<0.001). Risperidone therapy was associated with an average weight gain of 2.7+/-2.9 kg, as compared with 0.8+/-2.2 kg with placebo (P<0.001). Increased appetite, fatigue, drowsiness, dizziness, and drooling were more common in the risperidone group than in the placebo group (P<0.05 for each comparison). In two thirds of the children with a positive response to risperidone at eight weeks (23 of 34), the benefit was maintained at six months. CONCLUSIONS: Risperidone was effective and well tolerated for the treatment of tantrums, aggression, or self-injurious behavior in children with autistic disorder. The short period of this trial limits inferences about adverse effects such as tardive dyskinesia.

Acetyl-L-carnitine (ALC) in attention-deficit/hyperactivity disorder: a multi-site, placebo-controlled pilot trial.

OBJECTIVE: To determine whether acetyl-L-carnitine (ALC), a metabolite necessary for energy metabolism and essential fatty acid anabolism, might help attention-deficit/hyperactivity disorder (ADHD). Trials in Down's syndrome, migraine, and Alzheimer's disease showed benefit for attention. A preliminary trial in ADHD using L-carnitine reported significant benefit. METHOD: A multi-site 16-week pilot study randomized 112 children (83 boys, 29 girls) age 5-12 with systematically diagnosed ADHD to placebo or ALC in weight-based doses from 500 to 1500 mg b.i.d. The 2001 revisions of the Conners' parent and teacher scales (including DSM-IV ADHD symptoms) were administered at baseline, 8, 12, and 16 weeks. Analyses were ANOVA of change from baseline to 16 weeks with treatment, center, and treatment-by-center interaction as independent variables. RESULTS: The primary intent-to-treat analysis, of 9 DSM-IV teacher-rated inattentive symptoms, was not significant. However, secondary analyses were interesting. There was significant (p = 0.02) moderation by subtype: superiority of ALC over placebo in the inattentive type, with an opposite tendency in combined type. There was also a geographic effect (p = 0.047). Side effects were negligible; electrocardiograms, lab work, and physical exam unremarkable. CONCLUSION: ALC appears safe, but with no effect on the overall ADHD population (especially combined type). It deserves further exploration for possible benefit specifically in the inattentive type.

Adverse Events of Atomoxetine in a Double-Blind Placebo-Controlled Study in Children with Autism.

OBJECTIVE: Attention-deficit/hyperactivity disorder (ADHD) symptoms, including inattention and over activity, occur in approximately one-third of children with autism spectrum disorder (ASD). We describe the rate and duration of adverse events in a randomized controlled trial of atomoxetine (ATX) and parent training (PT) for ADHD symptoms and noncompliance in children with ASD. METHODS: We conducted a 10-week, double-blind, 2 × 2 trial of ATX and PT with 128 children (ages 5-14) randomized to ATX alone, ATX+PT, placebo+PT, or placebo alone. For 6 weeks, ATX (or placebo) doses were clinically adjusted to a maximum of 1.8 mg/(kg·day) and maintained for an additional 4 weeks. An average of seven PT sessions were conducted in the two PT arms. Adverse events (AEs) were assessed through parent ratings of common symptoms on a seven-point Likert severity scale and through direct interviews with study medical staff. RESULTS: ATX was associated with decreased appetite and fatigue, but was otherwise well tolerated. Most reported AEs lasted 4 weeks or less. Unlike reports with typically developing (TD) children, there were no concerns with QTc changes or suicidal ideation. CONCLUSIONS: This study extends the findings of previous studies of ATX in ASD by documenting that the type of AEs was similar to that of TD children, with no significant safety concerns.

A Randomized, Placebo-Controlled Trial of Metformin for the Treatment of Overweight Induced by Antipsychotic Medication in Young People With Autism Spectrum Disorder: Open-Label Extension.

OBJECTIVE: A previous study reported on a 16-week placebo-controlled, randomized clinical trial (RCT) of metformin for weight stabilization in 61 children and adolescents 6 to 17 years old with autism spectrum disorder who were prescribed atypical antipsychotics. The present study describes the results of a 16-week open-label extension. METHOD: Fifty-two participants from the acute trial (85%) entered the extension; 22 had been on metformin during the initial RCT and 30 had been on placebo. Participants were re-titrated to 500 mg twice a day (6- to 9-year-olds) or 850 mg twice a day (10- to 17-year-olds) during the open-label extension. Primary outcome measure was change in body mass index (BMI) z-score after 16 weeks; secondary outcomes were change in additional body composition and metabolic parameters. RESULTS: After 16 weeks of open-label treatment, participants initially taking placebo during the RCT had lower BMI z-scores (mean 16-week change -0.10, p = .004). Statistically significant improvements also were noted in secondary body composition measures (weight z-score and BMI and weight percentile) but not in metabolic variables. Participants who initially had been taking metformin during the 16-week RCT maintained prior decreases in BMI z-scores but did not have additional weight loss. Three participants discontinued treatment because of an adverse event. No significant changes were noted on metabolic measures, although the decrease in hemoglobin A1c was large (∼1 mmol) and consistent across the acute and open-label phases. CONCLUSION: Metformin can be effective for decreasing weight gain associated with atypical antipsychotic use and maintaining prior improvement in children and adolescents with autism spectrum disorder. Clinical trial registration information-Treatment of Overweight Induced by Antipsychotic Medication in Young People With Autism Spectrum Disorders (ASD); http://clinicaltrials.gov/; NCT01825798.

Risperidone and adaptive behavior in children with autism.

OBJECTIVE: To evaluate the impact of risperidone on adaptive behavior in children with autistic disorder who have serious behavior problems and to examine different methods of scoring the Vineland Adaptive Behavior Scales to measure change. METHOD: Forty-eight children (5 years to 16 years, 5 months) who showed behavioral improvement during acute treatment with risperidone were followed for 6 months and assessed with the Vineland Scales. RESULTS: Raw scores, age-equivalents, and special norm percentile scores all showed significant increases in adaptive behavior in the areas of communication, daily living skills, and socialization (p <.01). During a period of 6 to 8 months, children gained an average of 7.8 age-equivalent months in the area of socialization, a > 6% improvement beyond what would be expected based on baseline growth rates. CONCLUSIONS: Although limited by the absence of a control group, these results suggest that risperidone may improve adaptive skills in children with autistic disorder accompanied by serious behavioral problems. Vineland age-equivalent scores appear to be most useful in assessing change with treatment over time.

Validity of the autism diagnostic interview-revised.

The factor structure, internal consistency, and convergent validity of the Autism Diagnostic Interview-Revised (ADI-R) algorithm items were examined in a sample of 226 youngsters with pervasive developmental disabilities. Exploratory factor analyses indicated a three-factor solution closely resembling the original algorithm and explaining 38% of the variance, with one significant discrepancy: Unlike the algorithm, all nonverbal communication items were associated with the Social factor. Internal consistencies of domain scores ranged from .54 to .84. Correlations between ADI-R domain and total scores and instruments assessing adaptive behavior, psychopathology, and autism were examined. They indicated some similarities between constructs, but also that the ADI-R measures autism in a unique fashion.