Exogenous testosterone, aggression, and mood in eugonadal and hypogonadal men

To investigate (1) the effects of exogenous testosterone (T) on self- and partner-reported aggression and mood and (2) the role of trait impulsivity in the T-aggression relationship. Thirty eugonadal men with partners were randomized into two treatment groups to receive: (1) 200 mg im T enanthate weekly for 8 weeks or (2) 200 mg im sodium chloride weekly for 8 weeks. Eight hypogonadal men received 200 mg im T enanthate biweekly for 8 weeks. All groups completed a battery of behavior measures at baseline (Week 0) and at Weeks 4 and 8. Cognitive and motor impulsivity were the only predictors of self-reported total aggression (over and above age and T levels) at Weeks 0, 4, and 8. No significant changes in aggression or mood levels were found in the eugonadal-treated group. Significant reductions in negative mood (tension, anger, and fatigue) followed by an increase in vigor were found in response to T treatment in the hypogonadal group. These results demonstrate that inability to control one's behavior when such control is required by a particular situation (impulsivity) was found to significantly predict levels of aggression over and above age and T level. These data do not support the hypothesis that supraphysiological levels of T (within this range) lead to an increase in self- and partner-reported aggression or mood disturbances. Instead, for the first time, this study has identified the high level of negative affect experienced by hypogonadal patients. These findings have implications for T replacement therapy and male contraception.