Neurobehavioral theories of autism have hypothesized core deficits in sensory input or perception, basic attentional abilities or generalized attention to extrapersonal space, anterograde memory, auditory information processing, higher order memory abilities, conceptual reasoning abilities, executive function, control mechanisms of attention, and higher order abilities across domains. A neuropsychologic battery designed to investigate these hypotheses was administered to 33 rigorously diagnosed autistic individuals with IQ scores greater than 80, and 33 individually matched normal controls. Stepwise discriminant function was used to define the profile of neuropsychologic functioning across domains. The neuropsychologic profile in these autistic individuals was defined by impairments in skilled motor, complex memory, complex language, and reasoning domains, and by intact or superior performance in the attention, simple memory, simple language, and visual–spatial domains. This profile is not consistent with mental retardation or with a general deficit syndrome, but rather with a selective impairment in complex information processing that does not involve visual–spatial processing. This profile is not consistent with a single primary deficit, but with a multiple primary deficit model in which the deficit pattern within and across domains is reflective of the complexity of the information processing demands. This neuropsychologic profile is furthermore consistent with the neurophysiologic characterization of autism as a late information processing disorder with sparing of early information processing. (JINS, 1997, 3, 303–316)

A Wechsler Intelligence Scale profile characterized by VIQ < PIQ with lowest subtest score on Comprehension and highest on Block Design has been associated with autism. Recently, this profile has been applied to assess the accuracy of diagnosis in research samples and for differentiating autism from similar disorders in high-functioning individuals. Universality of this profile, however, has not been sufficiently demonstrated. We therefore examined WISC-R and WAIS-R profile characteristics in 81 rigorously diagnosed high-functioning (VIQ and FSIQ > 70) children (n = 45) and adults (n = 36) with autism. Analysis of the profiles in these groups did not reveal the presumed typical VIQ < PIQ pattern. The typical subtest pattern was found, but the magnitude of profile variability was small. We concluded that individuals with autism can demonstrate a wide range of ability levels and patterns on the Wechsler scales, without a single characteristic prototype. Use of IQ score profiles in the diagnosis and differential diagnosis of autism in high-functioning individuals is not considered valid.

Academic achievement levels in 54 high functioning (IQ > 70) autistic subjects were compared with those of 41 normal controls, who did not differ significantly in age, IQ, gender, race, or SES from the autistic subjects. The measures of academic achievement used included portions of the Detroit Tests of Learning Aptitude-2, the Woodcock Reading Mastery Test, and the Kaufman Test of Educational Achievement. Based on prior neuropsychological findings, it was hypothesized that autistic subjects would not differ from controls on subtests assessing mechanical and procedural skills, but would differ on subtests measuring comprehension and interpretive skills. As predicted, the autistic subjects performed significantly less well than controls on comprehension tasks, but not on mechanical reading, spelling, and computational tasks. This pattern is at variance with the typical academic profile of individuals with disabilities in reading or spelling, but shares some features with the nonverbal learning disabilities.

Verbal individuals with autism provide an important opportunity for investigating the qualitative nature of speech and language impairments in autism. In this study, a psychometric analysis of the language performance of 62 high-functioning autistic (HFA; Full Scale IQ and Verbal IQ > 70) participants was compared with that of 50 control participants matched for age, IQ, gender, race, education, and family socioeconomic distribution. Tests were included to compare basic procedural linguistic skills with complex, interpretive linguistic skills. The HFA participants did as well as controls on basic procedural language tests, but significantly less well on tests of complex interpretive language abilities. This profile is consistent with neuropsychological reports of generalized deficits in complex information-processing abilities with preservation of basic skills in the same functional areas.Autism is a developmental disorder characterized by severely impaired capacity for affective contact, abnormalities in social behavior, poor verbal and nonverbal communicative abilities, impairment in imaginative abilities, and a restricted range of interests. Although frequently associated with mental retardation, mental retardation is not considered a core or universal feature of this disorder according to the Diagnostic and Statistical Manual of Mental Disorders (4th ed., DSM-IV; American Psychiatric Association, 1994). That is, autism is known to occur in the absence of mental retardation in the form of high-functioning autism (HFA; Ameli, Courchesne,

A battery of psychoeducational tests was administered to samples of high-functioning (IQ > 70) autistic subjects and normal controls. A previous psychoeducational study indicated the presence of preserved procedural and mechanical academic skills accompanied by impaired comprehension and interpretive skills in high-functioning autistic individuals. The present findings indicate that this psychoeducational pattern also has a developmental aspect. Younger (< 13 years) autistic subjects performed as well or better than younger controls on psychoeducational measures of mechanical and procedural skills, and on some complex, interpretive tasks. However, they performed more poorly than controls on tasks that involve following complex linguistic instructions. Younger autistic subjects and controls did not differ significantly from each other on interpretive tasks, while the older austic subjects did significantly more poorly than the older controls on such tasks. The findings are discussed in terms of early success, but subsequent decline, in the course of academic functioning in autism.