Autism and pervasive developmental disorders: concepts and diagnostic issues

The purpose of this report is to bring up to date available information on the defining features and diagnostic issues relating to autism and related disorders. We review the validity of the syndrome based on our last review (Rutter, 1978; Schopler, 1978). Subsequent data have produced refinement in our understanding of both diagnostic criteria and the nature of the basic deficit. Controversies over both the boundaries and the heterogeneity within the autism syndrome are evaluated according to available evidence. Diagnostic rating instruments for expediting systematic sample selection are critiqued, and leads for new research directions are suggested.