Review of adaptive behavior studies in mentally retarded persons with autism/pervasive developmental disorder.
People with both autism and ID score far worse in social and communication skills than non-autistic peers with ID, but their self-care and motor skills are equal—so match groups on those domains, not language level.
01Research in Context
What this study did
Kraijer (2000) read every paper that measured daily living skills in people who had both autism and intellectual disability. The goal was to see how these dual-diagnosed adults differed from adults who had only intellectual disability. The review pulled together scores from tools like the Vineland Adaptive Behavior Scales.
What they found
Across studies, the autism-plus-ID group always scored lower in social and communication domains. They also showed more tantrums, self-injury, and repetitive behavior. Surprisingly, self-help skills (toileting, dressing, eating) and motor skills were about equal between the two groups.
How this fits with other research
Jain et al. (2025) now sharpens the picture. Using the newer Vineland-III and a large sample, they show that even kids with social communication disorder—who have no ID—greatly outscore kids with ASD on every adaptive domain. The gap is largest in communication and socialization, backing the 2000 finding that these are the core deficit areas.
Paul et al. (2014) extends the timeline downward. They found the same adaptive lags in toddlers under two, proving the gap starts almost from birth. This supports Kraijer (2000) but shows the problem is evident far earlier than the adult institutions reviewed.
Klin et al. (2007) adds a twist: youth with ASD and normal IQ still fall behind in daily living skills, and the gap widens with age. This seems to clash with Kraijer (2000), who said self-help scores were equal when ID was present. The difference is IQ: once you remove ID, the autism-only group still struggles with independence, revealing that adaptive deficits are part of autism itself, not just a by-product of low IQ.
Why it matters
When you match participants for studies—or write goals—use self-help or motor skills to equate groups, not social or communication scores. If you screen a teen with ASD and normal IQ, still run the Vineland; don’t assume good cognition equals good independence. Target daily living goals early and keep them on the plan even when IQ rises.
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02At a glance
03Original abstract
A review is presented of the investigations carried out concerning the adaptive behavior of persons with the dual disability of mental retardation and autism/PDD. A close correspondence is found between the results obtained by means of a Dutch set of scales, the SRZ, SGZ, and SMZ, and those obtained by means of the Vineland Adaptive Behavior Scales. Compared with matched nonautistic persons, the performance of dually disabled persons is found to be particularly poor in the domain Social Skills/Socialization and somewhat less poor in the domain Communication. Performance of the two categories does not differ in the domains Self Help/Daily Living Skills and Gross Motor Skills/Motor Skills. As a net result, persons of the dually disabled category are found to obtain comparatively low total scores for social competency, the SRZ-Total/Adaptive Behavior Composite. In addition, autistic mentally retarded persons are found to display more maladaptive behavior. For comparative studies in the mental retardation field the use of level of Self Help/Daily Living Skills and, to a lesser extent, level of Gross Motor Skills/Motor Skills are recommended as suitable matching variables.
Journal of autism and developmental disorders, 2000 · doi:10.1023/a:1005460027636