[The intelligence structure of autistic persons]

In a research project on the genetics of autistic disorders 115 subjects were examined. An autistic disorder was diagnosed in 102 of the subjects using the standardized Autism Diagnostic Interview (ADI; Le Couteur et al., 1989/ADI-R; Lord et al., 1994). The WAIS-R or WISC-R could be administered to 42 of the subjects. The mean full-scale IQ was 84.4, slightly below the range of normal intelligence. The mean verbal IQ (89.3) was considerably higher than the performance IQ (78.9). Analysis of the subtest patterns showed the highest scores to be in those subtests measuring knowledge of dates and facts and visuospatial abilities. The lowest scores were on subtests requiring an understanding of social relations and the ability to understand concrete social actions. This subtest pattern confirms results of other studies on the intelligence of individuals with autism and was independent of gender and level of intelligence. The subtest pattern appears to be specific for autistic disorder; it has been interpreted with reference to the theory of "weak central coherence" (Frith, 1989; Shah & Frith, 1993), which postulates that in autistic individuals stimulus perception and processing occurs independently of the general context. The results suggest that the differentiation between different types of autistic disorders should be abandoned in favor of a continuum of autistic disorders with differing degrees of severity.