Stimulant drug effects in developmental disorders and hyperactivity--toward a resolution of disparate findings.

An attempt is made to integrate data from a variety of clinical populations and from the animal literature. Evidence is presented suggesting that mentally retarded and autistic children generally show a poor response to stimulant medication, whereas hyperactive and normal children respond beneficially. Cognitive research in mentally retarded and autistic children is reviewed, and it is suggested that both diagnostic groups suffer from attentional difficulties, the mechanisms of which may be very similar. The literature on stimulant-induced stereotypy in animals is discussed, with emphasis on the clinical implications for autism and mental retardation. An attentional model is proposed to account for type of therapeutic response to stimulant medication. This is followed by a possible method for testing the model and by specific predictions relating to subject characteristics and response.