Effects of fenfluramine on eight outpatients with the syndrome of autism.

Fenfluramine was administered to eight autistic outpatients in a double-blind study to determine its effects on symptomatic behavior, developmental scores, blood serotonin levels and platelet counts. Two children benefited substantially according to academic and cognitive tests, parental and teacher reports and the principal investigator's clinical impressions. They also manifested behavioral and mood swings. The remaining six children showed varying degrees of response; one was withdrawn during the study by his parents. The greatest improvement occurred in children with an IQ above 40; the more severely retarded improved little, and primarily in the motor sphere.