THE EFFECTS OF PHENYTOIN ON IMPULSIVE AND PREMEDITATED AGGRESSION - ACONTROLLED-STUDY

Studies of the effects of phenytoin on aggression have produced equivo cal results primarily because of a lack of (1) common objective criter ion measures of aggressive acts across studies; (2) rigorous inclusion and exclusion criteria for selecting subjects; and (3) a nosologic ba sis for classifying different types of aggression. The current study w as designed to remedy these deficiencies. Aggression was defined using a nosology that defines three types of aggression: (1) medically rela ted; (2) premeditated; and (3) impulsive. The purpose of this study wa s to test the hypothesis that phenytoin will decrease impulsive aggres sive acts but not have a significant influence on premeditated aggress ive acts. Sixty inmates were divided into two groups on the basis of c ommitting primarily impulsive aggressive acts or premeditated aggressi ve acts while in prison. Medical aggression was ruled-out by subject s election. The study used a double-blind, placebo-controlled, crossover design. As hypothesized, phenytoin (200 mg a.m. and 100 mg p.m.) sign ificantly reduced impulsive aggressive acts but not premeditated aggre ssive acts. Event-related potentials (ERPs) measured information proce ssing in the cortex during drug/placebo conditions. The amplitudes of P300 ERP waveforms among impulsive aggressive subjects were increased significantly during the phenytoin condition but not during the placeb o condition. There were no significant changes in P300 ERP waveforms b etween drug/placebo conditions among nonimpulsive aggressive subjects.