First report of a Canadian epidemiological study of autistic syndromes.

This report describes an epidemiological investigation of the autistic syndrome using new research diagnostic criteria (Denckla, 1986). The focus here is on the methods of screening and follow-up, and on a description of the cases identified within a circumscribed region of Nova Scotia. Autism, as defined by social deviance, language impairment and repetitive or ritualistic behaviours, has a prevalence of 10 per 10,000 and a male to female ratio of 2.5:1. These findings are discussed relative to those reported previously.