Characterization of aggressive behavior and phenytoin response

Recent work has suggested that the success of pharmacological treatment for chronic aggressive behavior may depend, in part, on the subtype of aggressive behavior displayed (e.g. reactive, impulsive aggression vs. predatory, premeditated aggression). The present study examined the usefulness of characterizing aggressive behavior during a 16-week double-blind crossover study of phenytoin (PHT) treatment in 41 aggressive adult males. The Impulsive/Premeditated Aggression Scales (IPAS) were used to characterize aggressive behavior as predominantly impulsive or predominantly premeditated in nature. Analyses indicated that participants who did not respond to PHT treatment endorsed significantly more premeditated characteristics on the IPAS than those who responded to PHT treatment. Non-responders also exhibited fewer aggressive outbursts during placebo treatment, suggesting a greater level of behavior control. Participants who did not complete the study were younger, endorsed significantly more premeditated aggression characteristics and reported more lifetime antisocial behaviors than those who completed the study. Taken together, these data emphasize several factors that may influence the success of pharmacological treatment in aggressive individuals, namely the importance of characterizing the predominant type of problem aggressive behavior.