Validity of the sleep subscale of the Diagnostic Assessment for the Severely Handicapped-II (DASH-II)

Currently there are no available sleep disorder measures for individuals with severe and profound intellectual disability. We, therefore, attempted to establish the external validity of the Diagnostic Assessment for the Severely Handicapped-II (DASH-II) sleep subscale by comparing daily observational sleep data with the responses of direct care staff to the sleep subscale of the DASH-II. Participants included 25 individuals with severe intellectual disability and 25 individuals with profound intellectual disability who reside in a large developmental center in central Louisiana. Four of the five items of the DASH-II were shown to have external validity. Implications of these findings for future research and practice are discussed.     

Patterns of emotional and behavioural disturbance associated with autistic traits in young people with severe intellectual disabilities and challenging behaviours

Emotional and behavioural disturbance was assessed in 82 individuals with severe intellectual disabilities and challenging behaviour using the Diagnostic Assessment for the Severely Handicapped-II (DASH-II). Levels of disturbance were compared firstly in individuals with and without features of autism as assessed by the DASH-II, and secondly in individuals with varying severities of autism. In both cases levels of ability and overall severity of behaviour disorder were comparable across groups. Individuals with autistic features were found to have significantly higher scores than nonautistic individuals on the DASH-II organic disorder, anxiety, mania, PDD/autism and stereotypies subscales. When participants with autistic features were separated into groups of severe and moderate autism and compared with nonautistic participants, significant effects of group were found for scores on the anxiety, mood, mania, PDD/autism, schizophrenia and stereotypies subscales. Scheffé tests were conducted to further evaluate between-group differences. Item analysis showed seven DASH-II items to have a 30% or more difference between levels of endorsement in autistic and nonautistic individuals, with six further items showing a 20% or greater difference in levels of endorsement. Findings are compared to those from previous research and implications for the conceptualisation of emotional and behavioural disorders in individuals with autism are discussed.     

A Comparison of Speaking and Mute Individuals with Autism and Autistic-Like Conditions on the Autism Behavior Checklist

The item, total, and subscale scores on the Autism Behavior Checklist (ABC) were compared for 155 mute and 335 speaking individuals with autism spectrum disorders. Although no significant difference was observed between the groups on the ABC total score, the mute group demonstrated significantly more pathology on 21 of 57 items and 3 of 5 subscales. The speaking group obtained significantly higher scores on only 8 items and 1 subscale (Language). The appropriateness of providing greater pathology scores on expressive language items to speaking, rather than to mute, individuals is called into question. The authors speculate whether the expressive language items are weighted too heavily, in regard both to the Language subscale and to the ABC total score. If the expressive language items were removed, the mute group would have significantly higher ABC total scores and therefore a greater degree of autism severity.     

An Evaluation of the Gilliam Autism Rating Scale

The Gilliam Autism Rating Scale was developed to identify individuals with autism in research and clinical settings. It has benefited from wide use and acceptance but has received little empirical attention. The purpose of this study was to evaluate the construct and diagnostic validity, interrater reliability, and effects of participant characteristics of the GARS in a large and heterogeneous sample of children and adolescents with autism spectrum disorders. 360 parent and teacher ratings were submitted to factor analysis. A three-factor solution explaining 38% of the variance was obtained. Almost half of all items loaded on a Repetitive and Stereotyped Behavior factor. The Developmental Disturbance subscale did not contribute to the Autism Quotient (AQ) and was poorly related to other subscales. Internal consistency for the three behavioral subscales was good but low for the Developmental Disturbance subscale. The average AQ was significantly lower than what was reported in the test manual, suggesting low sensitivity with the current cutoff criteria. Interrater reliability was also much lower than originally reported by the instrument’s developer. No significant age or gender effects were found. Level of impairment, as measured by adaptive behavior, was negatively related to total and subscale scores. The implications of these findings were discussed, as was the use of diagnostic instruments in the field in general.     

Mania and behavioral equivalents: A preliminary study

Previous research has failed to address the possibility of behavioral equivalents in people with ID and mania. The relationship between a measure of mania and possible behavioral equivalents was assessed in 693 adults, most with severe or profound ID, living in a large residential setting. The mania subscale of the DASH-II proved to be a homogenous scale, suggesting that this may be a valid measure of mania in individuals with ID. Both item and factor analyses and correlations showed that many behavioral items acceptably correlated with the mania items. There may be some challenging behaviors that are related to mania in individuals with ID. A factor analysis noted a decreased need for sleep, restlessness, agitation, and irritability as items associated with mania.     

The validity of the autism spectrum disorders-diagnosis for intellectually disabled adults (ASD-DA)

Psychologists interviewed direct-care staff using a battery of assessment measures including the autism spectrum disorders-diagnosis for intellectually disabled adults (ASD-DA), the Diagnostic Assessment for the Severely Handicapped-II (DASH-II), the Matson Evaluation of Social Skills for Individuals with Severe Retardation (MESSIER), the Socialization domain of the Vineland Adaptive Behavior Scales (VABS), and a checklist containing criteria for autism and PDD-NOS from the DSM-IV-TR and ICD-10. Three hundred and seven intellectually disabled (ID) adolescents and adults ranging in age from 16 to 88 were assessed. Participants were diagnosed with either ID and ASD (autism or PDD-NOS; n=156) or ID and no Axis I diagnosis (n=151). A modification of the multitrait-multimethod approach was used to establish the convergent and discriminant validity of the ASD-DA. The scale proved to have robust convergent validity when correlated with the DSM-IV-TR/ICD-10 checklist, MESSIER, and Socialization domain of the VABS. Additionally, discriminant validity was demonstrated by comparing the ASD-DA to items from the DASH-II (measure of general psychopathology). The implications of these data are discussed.     

Validity of the Aberrant Behavior Checklist in Children with Autism Spectrum Disorder

The Aberrant Behavior Checklist (ABC) is a widely used measure in autism spectrum disorder (ASD) treatment studies. We conducted confirmatory and exploratory factor analyses of the ABC in 1,893 children evaluated as part of the Autism Treatment Network. The root mean square error of approximation was .086 for the standard item assignment, and in exploratory factor analysis, the large majority of items continued to load on the originally assigned factors. Correlations between the ABC subscales and multiple external variables including the Child Behavior Checklist and demographic variables supported the convergent and divergent validity of the ABC as a measure of behavior problems in ASD. Finally, we examined the impact of participant characteristics on subscale scores and present normative data.     

A factor analytic study of the Autism Behavior Checklist

The factor structure of the Autism Behavior Checklist (ABC) (Krug, Arick, & Almond, 1980a, 1980b), a 57-item screening instrument for autism, was examined on a sample of 383 individuals with autism spectrum disorders (i.e., autistic disorder, Asperger syndrome, and other autism-like conditions) aged 5-22 years. A five-factor model accounted for 80% of the total variance in the checklist. Thirty-nine of the 57 items had factor loadings of 0.4 or more, with 13 items loading on Factor 1, 11 items on Factor 2, 6 items on Factor 3, 5 items on Factor 4, and 4 items on Factor 5. No support was found for classifying the 57 items into the five subscales proposed by Krug et al. (1980a, 1980b) or for the three-factor solution suggested by Wadden, Bryson, and Rodger (1991).     

Diagnosing Autism: Analyses of Data from the Autism Diagnostic Interview

Results from ROC curves of items from two scales, the Autism Diagnostic Interview (ADI) and Autism Diagnostic Interview-Revised (ADI-R), operationalizing DSM-IV criteria for autism are presented for 319 autistic and 113 other subjects from 8 international autism centers. Analyses indicate that multiple items were necessary to attain adequate sensitivity and specificity if samples with varying levels of language were considered separately. Although considering only current behavior was generally sufficient when a combination cutoff and additive model was employed, predictive power was highest when history was taken into account. A single set of criteria, as operationalized by individually structured questions in the ADI/ADI-R, was effective in differentiating autism from mental handicap and language impairment in subjects with a range of chronological ages and developmental levels.     

The Psychopathology in Autism Checklist (PAC): A pilot study

Adults with autism and intellectual disability (ID) are assumed to have high vulnerability for developing psychiatric disorders, but instruments or criteria for identifying those who may be in need of psychiatric services have been lacking. This study presents a new carer-completed screening checklist designed for this purpose.Differentiation between symptoms related to autism and to psychiatric disorders is indicated in order to identify psychiatric disorders in persons with autism. The Psychopathology in Autism Checklist (PAC) contains 30 items representing symptoms previously evaluated as specific to one of four major psychiatric disorders (psychosis, depression, anxiety and OCD) and not related to autism. Twelve items evaluated as indicators of general adjustment problems are also included. All 42 items are based on ICD-10 and DSM-IV criteria.The PAC was piloted on a sample of 35 adults with autism and ID. The score of participants previously identified with co-occurring psychiatric disorders (i.e. psychosis, depression, anxiety disorder, or OCD) were compared with the score of participants without psychiatric disorders.The results indicate acceptable psychometric properties, and that the PAC discriminates between adults with autism and ID with and without psychiatric disorders, and partially between individuals diagnosed with different psychiatric disorders.     

Preliminary Study of the Autism Self-Efficacy Scale for Teachers (ASSET)

The purpose of the current study was to evaluate a new measure, the Autism Self-Efficacy Scale for Teachers (ASSET) for its dimensionality, internal consistency, and construct validity derived in a sample of special education teachers (N = 44) of students with autism. Results indicate that all items reflect one dominant factor, teachers’ responses to items were internally consistent within the sample, and compared to a 100-point scale, a 6-point response scale is adequate. ASSET scores were found to be negatively correlated with scores on two subscale measures of teacher stress (i.e., self-doubt/need for support and disruption of the teaching process) but uncorrelated with teacher burnout scores. The ASSET is a promising tool that requires replication with larger samples.     

The Modified Checklist for Autism in Toddlers: An Initial Study Investigating the Early Detection of Autism and Pervasive Developmental Disorders

Autism, a severe disorder of development, is difficult to detect in very young children. However, children who receive early intervention have improved long-term prognoses. The Modified Checklist for Autism in Toddlers (M-CHAT), consisting of 23 yes/no items, was used to screen 1,293 children. Of the 58 children given a diagnostic/developmental evaluation, 39 were diagnosed with a disorder on the autism spectrum. Six items pertaining to social relatedness and communication were found to have the best discriminability between children diagnosed with and without autism/PDD. Cutoff scores were created for the best items and the total checklist. Results indicate that the M-CHAT is a promising instrument for the early detection of autism.     

Self-reported social skills impairment explains elevated autistic traits in individuals with generalized social anxiety disorder

Screening for autism in individuals with generalized social anxiety disorder (GSAD) is complicated by symptom overlap between GSAD and autism spectrum disorder (ASD). We examined the prevalence of self-reported autistic traits within a sample of participants with a diagnosis of GSAD (n = 37) compared to individuals without a GSAD diagnosis (NOSAD; n = 26). Of the GSAD sample participants, 70.84% self-reported autistic traits above a cut-off of 65 on the Autism Quotient-Short (AQ-S) and reported significantly more autistic traits on 3 of 5 AQ-S subscales compared to the NOSAD group. Diagnosis uniquely predicted variation in the social skills subscale above and beyond the other subscales and other predictors. Furthermore, variation in the social skills subscale largely explained group differences on the other subscales. Our results suggest caution in utilizing measures like the AQ-S with clinical populations characterized by social difficulties such as individuals with a GSAD diagnosis.     

Symptoms of psychopathology in adults with intellectual disability and seizures

Seizures are more common in individuals with intellectual disabilities than in the general population. As a result, differences in functioning for individuals with intellectual disability with and without seizures have been evaluated. Research on differences in psychopathology for individuals with intellectual disability with and without seizures has been mixed. The purpose of this study was to examine differences in subscale scores on the Diagnostic Assessment for the Severely Handicapped-II (DASH-II) between individuals with intellectual disability with and without seizures. In this study, 321 individuals from two large developmental centers in the southeastern United States were administered the DASH-II. Researchers found that the seizure group endorsed significantly more symptoms on the mood subscale than the group without seizures. No other group differences were found to be significant. Implications of these results are discussed.     

Factor Analysis of Restricted and Repetitive Behaviors in Autism Using the Autism Diagnostic Interview-R

The current study examined the factor structure of restricted and repetitive behaviors (RRB) in children with autism. Factor extraction procedures of 12 items from the Autism Diagnostic Interview-Revised (ADI-R) were applied in N = 207 individuals with autism. Two interpretable factors were identified: Factor 1—repetitive sensory motor actions and Factor 2—resistance to change. There was a significant negative correlation between an index of level of adaptive functioning and Factor 1. Intraclass correlations were not significant for either factor in a subset of families with two or more siblings with autism (multiplex). No differences in scores were apparent for either factor when multiplex families and families containing only one affected individual with autism (singleton) were compared. RRB in autism are represented by two distinct factors which may reflect two separate groups within autism. Defining subgroups within autism will allow for reduction of clinical heterogeneity and enhance our ability to dissect the genetic etiology of this complex disorder.     

Prevalence of autism in an urban population of adults with severe intellectual disabilities – a preliminary study

Background Research on the prevalence of autism in Iceland has indicated that one possible explanation of fewer autism cases in older age groups was due to an underestimation of autism in individuals with intellectual disabilities (IDs). The present study systematically searched for autism cases in the adult population of individuals with severe ID living in the city of Reykjavik, Iceland. Methods Potential participants (n = 256) were recruited through the Regional Office for the Affairs of the Handicapped in Reykjavik. First, a screening tool for autism was applied, followed by the Childhood Autism Rating Scale and finally the Autism Diagnostic Interview‐Revised (ADI‐R). Results The point prevalence of severe ID was 3.7/1000 (95% CI 3.2–4.1) with a male–female ratio of 1.2:1. Participation rate in the study was 46.5%. Participants were younger than non‐participants and more often residents of group homes. The prevalence of autism was 21% (25/119) (95% CI 14.7–29.2) with a male–female ratio of 1.8:1. Of the individuals with autism, 10/25 (40%) were verbal according to the ADI‐R definition, and 18/25 (72%) had active epilepsy and/or other neurological conditions and handicaps. Conclusion The study identified twice the number of autism cases than those previously recognised within the service system. Autism is a prevalent additional handicap in individuals with severe ID, which should always be considered in this population. There are indications that the estimated prevalence of autism found should be considered minimal.     

The Autism Diagnostic Interview-Revised and the Childhood Autism Rating Scale: Differences Between Diagnostic Systems and Comparison Between Genders

Diagnoses for autism based on the Autism Diagnostic Interview-Revised (ADI-R) and the Childhood Autism Rating Scale (CARS) were examined for 83 individuals with suspected autism. Agreement between systems reached 85.7%. Participants receiving diagnosis of autism based on only one system were significantly younger in age than individuals receiving diagnoses according to both systems. Individuals who did not receive diagnosis of autism on the ADI-R had lower chronological and mental ages and lower CARS scores compared to individuals who received diagnosis of autism based on the ADI-R. Eighteen females and 18 males were matched to examine possible gender differences. No significant findings were revealed, suggesting that the symptoms of autism according to the ADI-R and CARS do not differ between males and females when matched for chronological and mental ages.     

The Autism Diagnostic Observation Schedule—Generic: A Standard Measure of Social and Communication Deficits Associated with the Spectrum of Autism

The Autism Diagnostic Observation Schedule—Generic (ADOS-G) is a semistructured, standardized assessment of social interaction, communication, play, and imaginative use of materials for individuals suspected of having autism spectrum disorders. The observational schedule consists of four 30-minute modules, each designed to be administered to different individuals according to their level of expressive language. Psychometric data are presented for 223 children and adults with Autistic Disorder (autism), Pervasive Developmental Disorder Not Otherwise Specified (PDDNOS) or nonspectrum diagnoses. Within each module, diagnostic groups were equivalent on expressive language level. Results indicate substantial interrater and test—retest reliability for individual items, excellent interrater reliability within domains and excellent internal consistency. Comparisons of means indicated consistent differentiation of autism and PDDNOS from nonspectrum individuals, with some, but less consistent, differentiation of autism from PDDNOS. A priori operationalization of DSM-IV/ICD-10 criteria, factor analyses, and ROC curves were used to generate diagnostic algorithms with thresholds set for autism and broader autism spectrum/PDD. Algorithm sensitivities and specificities for autism and PDDNOS relative to nonspectrum disorders were excellent, with moderate differentiation of autism from PDDNOS.     

Brief Report: Assessment of the Social-Emotional Profile in Children with Autism Spectrum Disorders using a Novel Comic Strip Task

This study investigated whether the novel Comic Strip Task (CST) could be used to detect Theory-of-Mind impairments (ToM) in 4- to 8-year-old children with high functioning Autism Spectrum Disorders (ASD). Twelve children with either high-functioning autism or Asperger’s Disorder and 12 typically-developing children completed the 21-item measure. The overall CST demonstrated moderate internal consistency but the Belief-understanding subscale was excluded from the test due to poor reliability. As predicted, the ASD group performed significantly more poorly than controls on the overall 2-subscale CST and on the intention-understanding subscale. No group differences were found in emotion-understanding subscale performance. Controlling for age, verbal ability was positively correlated with overall CST performance across groups. CST performance in the ASD group positively correlated with parent-reports of communication difficulties. Despite some limitations with the belief-understanding subscale, the CST has promising psychometric features warranting further development of this measure.     

Exploratory subsetting of autism families based on savant skills improves evidence of genetic linkage to 15q11-q13

OBJECTIVE: Autism displays a remarkably high heritability but a complex genetic etiology. One approach to identifying susceptibility loci under these conditions is to define more homogeneous subsets of families on the basis of genetically relevant phenotypic or biological characteristics that vary from case to case. METHOD: The authors performed a principal components analysis, using items from the Autism Diagnostic Interview, which resulted in six clusters of variables, five of which showed significant sib-sib correlation. The utility of these phenotypic subsets was tested in an exploratory genetic analysis of the autism candidate region on chromosome 15q11-q13. RESULTS: When the Collaborative Linkage Study of Autism sample was divided, on the basis of mean proband score for the "savant skills" cluster, the heterogeneity logarithm of the odds under a recessive model at D15S511, within the GABRB3 gene, increased from 0.6 to 2.6 in the subset of families in which probands had greater savant skills. CONCLUSIONS: These data are consistent with the genetic contribution of a 15q locus to autism susceptibility in a subset of affected individuals exhibiting savant skills. Similar types of skills have been noted in individuals with Prader-Willi syndrome, which results from deletions of this chromosomal region.