Influence of trait hostility on tryptophan depletion-induced laboratory aggression.

Previous research has indicated that laboratory aggression in men increases after temporarily reducing the synthesis and neurotransmission of serotonin (5-HT) in the brain using the plasma L-tryptophan (Trp) depletion technique. Further research indicates that male subjects selected for high trait hostility are particularly prone to increased aggression following plasma Trp depletion. In a recent study of laboratory aggression in male control subjects, we demonstrated that laboratory aggression increased following ingestion of a Trp-depleting beverage, but not after ingestion of a Trp-containing beverage nor under food-restricted conditions. We report here that the increases in aggression under Trp-depleted conditions were specific to men who scored the highest on the Buss-Perry Aggression Questionnaire. These preliminary data support earlier findings that compared to non-hostile men, hostile men may be more prone to behavior change induced by the perturbation of the 5-HT neurotransmitter system.