Effects of L-5-hydroxytryptophan in autistic children.

Behavioral effects of L-5-Hydroxytrophan (L-5-HTP), administered in combination with carbidopa, were evaluated in three autistic children using direct behavioral observation and parent ratings. Children were assessed under each of four experimental conditions: Baseline, Placebo I, L-5-HTP plus carbidopa, and Placebo II. During the 20-week study two children showed behavioral change that appeared to be unrelated to drug treatment. The findings did not support the hypothesis that a functional deficit in brain 5-HT underlies the autistic syndrome.