Research showed that features of ASD can change over the course of development. Only a limited number of studies assessed cognitive strengths and impairments in high-functioning adults with ASD and results were contradictory. Therefore, it is not clear whether the three characterizing cognitive theories are still appropriate when individuals with ASD reach adulthood.
To examine the intelligence profiles, theory of mind, central coherence and executive functioning in adults with the autistic disorder, Asperger syndrome and a neurotypical adult group.
The research project encompassed four studies in which the intelligence profile and the three cognitive theories were examined in adults with autistic impairment and in a healthy control group. Neuropsychological instruments and self-report questionnaires were used. In each study, the research groups were matched in age and gender. The mean age of the ASD population varied between 38 and 43 years. The diagnoses were based on ADI-R and structured DSM-IV interviews, differentiation between autism and Asperger syndrome was based on criteria of Gillberg & Gillberg and ICD-10.
The HFA group was impaired in the speed of processing information, compared to the Asperger and neurotypical groups. The two disorder groups were impaired in advanced theory of mind and reported a detailed information processing style. Furthermore, they reported more use of systemizing strategies than the neurotypical group. No specific impairment has been found in working memory and in switching and using strategies in any of the groups.
In the areas of theory of mind and central coherence, the self-reports appeared more predictable for the presence of ASD than the neuropsychological tasks.
In high-functioning adults with ASD, the theories of 'impaired theory of mind' and a 'detailed information processing style' are still relevant. However, there is less evidence for impairment in executive functioning in these individuals.
The impairment in speed of processing information should be taken into account when interpreting performance on cognitive tasks that aim to measure certain cognitive areas.
Based on our studies we want to emphasize the usefulness of self-reports in high-functioning adults with ASD. Apparently, compensating strategies, possibly related to relatively high intelligence, enables these individuals to recognize their strengths and weaknesses relatively adequate.
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