Early detection of childhood autism: a review of screening instruments and rating scales.

The detection and diagnosis of autism may be delayed until middle childhood, 3-4 years after its onset. This is more likely in high-functioning autism and in cases of co-morbidity with mental retardation. Such delays have serious effects on children and their families as well as on the provision of clinical and educational resources. In addition to greater awareness among professionals and to the development of comprehensive services, early detection could be facilitated by screening for early signs and symptoms of autism. The instruments that have been developed to rate autistic behaviours, particularly in pre-school children, are reviewed in this paper. Although the majority of these observational or informant-based measures were not initially designed for screening purposes, previous research findings from their application could be useful in the future development of such a screening instrument. Relevant research findings are discussed and suggestions are made for further evaluation in appropriate populations.