Abstract

The present study investigated the effects of serotonin and psychosocial factors including Cook-Medley hostility, Trait anger, Trait anxiety, and Beck depression scores on cardiovascular and mood responses to interpersonal stress. Eighty-five males and females participated in either an acute tryptophan depletion, a procedure that lowers brain serotonin levels, or a sham tryptophan depletion. They were subsequently exposed to an interpersonal conflict stressor. Cardiovascular and mood measures were recorded at baseline, post-depletion pre-stress, during the stressor, and during recovery. All participants exhibited heightened cardiovascular responses as well as increased anxious, hostile, and depressed mood to the interpersonal conflict. Effects of depletion on cardiovascular reactivity were observed exclusively during recovery. Effects of depletion on negative mood were found at rest and during stress with increased negative affect in the depleted versus balanced condition. Interactions between tryptophan depletion and psychological factors other than hostility were also observed. Greater negative mood responses were found in depleted individuals with high scores on anger, anxiety, and depression factors. Overall, these findings suggest that the effect of serotonin on the stress response may be modulated by psychological factors. Implications for future research on the interaction between serotonin, psychological factors, cardiovascular reactivity, and mood are discussed.