Defining the intellectual profile of Asperger Syndrome: comparison with high-functioning autism.

Asperger syndrome (AS) is a disorder of early childhood characterized by autistic social deficits, subtle communication impairment, and excessive isolated interests. There is no history of language delay or of mental retardation. Despite its increasing popularity as a distinct condition, its diagnostic validity remains uncertain. It is still unclear to what extent AS differs from autism with normal intelligence sometimes referred to as high-functioning autism (HFA). However, some reports have suggested that persons with AS possess a distinct profile on tests of intelligence characterized by a high verbal IQ and a low performance IQ, whereas in most cases with HFA, the pattern is reversed. Since few studies have directly compared AS subjects with HFA controls using unmodified diagnostic criteria and standardized measures of assessment, in this report we compared 22 AS subjects with 12 HFA controls, matched on age, sex and level of intelligence. As a group, subjects with AS showed a higher verbal IQ and higher scores on information and vocabulary subtests than those with HFA. However, scores of several AS and HFA subjects showed a mixed pattern. Implications of these findings are discussed in the context of the validity of Asperger Syndrome.