Fenfluramine effects on impulsivity in a sample of adults with and without history of conduct disorder

Rationale: The role of serotonin in impulsivity was examined by administering the serotonin-releasing drug, d,1-fenfluramine, and measuring effects on impulsive responding of male subjects with and without a history of conduct disorder (CD) under controlled laboratory conditions. Methods: Five adult male subjects with a history of CD and five matched controls were recruited into a study to determine the acute effects of d,1-fenfluramine on a laboratory measure of impulsive behavior. This laboratory measure, based upon delay of gratification, presented subjects with choices between a small reward after a short delay and a larger reward after a longer delay. Impulsive behavior was indicated by frequent choices for the smaller reward. Results: Acute oral doses of d,l-fenfluramine (0.21, 0.42, and 0.85 mg/kg) produced decreases in the number of impulsive choices in all subjects with a history of CD, but had no effect on the control subjects. Conclusions: This data suggests that a deficit in serotonin and/or dopamine may play a role in impulsivity in CD subjects, and drugs which act to reduce this biological deficit can reduce impulsiveness.