| Abstract: | The use of an investigator-based interview (Autism Diagnostic Interview—Revised; ADI-R) in the diagnosis of 51 autistic and 43 nonautistic mentally handicapped preschool children of equivalent mental and chronological age is described. Significant differences occurred between the groups on every diagnostic subdomain from the DSM-IV/ICD-10 draft criteria, except specific aspects of stereotyped language, still relatively rare in these young children. All but one of the 51 children judged to be autistic by clinical observation and only two of the 30 nonautistic mentally handicapped children with mental ages of 18 months or higher met criteria for autism on an algorithm to DSM-IV/ICD-10 draft criteria. However, discrimination using domain totals between autistic and the 13 nonautistic, nonverbal mentally handicapped children with mental ages under 18 months was poor. Quality of social overtures to adults and peers, play, and unusual sensory behaviors and mannerisms continued to differentiate these two groups. The relevance of these findings to the diagnosis of autism in preschool children is discussed. |
