Two hundred and twenty-eight cases of children with final clinical diagnoses of childhood psychosis were reviewed using a standard coding scheme; cases were grouped in three broad categories on the basis of clinical diagnosis (autistic, atypical and schizophreniform). These three groups differed significantly in many respects, although the ‘atypical’ group more closely resembled the autistic group. While it was possible meaningfully to differentiate diagnostic groups using DSM-III criteria, some cases were difficult to classify. Childhood schizophrenia, as strictly defined, was far less common than childhood autism. The development of diagnostic schemes for those children whose disorders are difficult to classify is an important topic for future research.

Eight young adults with autism and autistic-like pervasive developmental disorders (PDD) and eight mentally retarded adults were matched for nonverbal IQ and given a series of standard language tests. They were then engaged in conversations into which examiners injected three types of contingent query requests for clarification (‘I watched “Dynasty” last night.’ “You watched what?”). Results of the standard language measures revealed that the PDD group was inferior in all areas except articulation. Responses to the contingent, query task showed the PDD group to be both less specific and less willing to supply information beyond that directly queried. Implications of these results for understanding the social and linguistic deficiencies in autism are discussed.

Analyses were undertaken to examine whether a wide range of psychiatric disorders, including anxiety, affective, substance abuse and psychotic disorders, represent variant manifestations of Tourette's syndrome (TS). Previous studies have suggested that chronic tics (CT) and obsessive-compulsive disorder (OCD) are variant expressions of TS since both CT and OCD are elevated among relatives of TS probands. In the current study, no other psychiatric disorder was significantly elevated among the relatives who did not have TS, CT or OCD when compared with a control sample. These findings are not consistent with the hypothesis that a wide range of psychiatric and behavioural disorders are variant expressions of TS.