The role of alcohol and steroid hormones in human aggression

The association between alcohol and aggressive behavior is well established although a direct causal relationship has proven hard to demonstrate. There are, however, indications that alcohol facilitates aggression in individuals who already have a predisposition to behave aggressively. Aggressive personality disorders have in turn been explained by elevated testosterone level. A one-to-one relation between increased levels of testosterone and aggression has been, nevertheless, difficult to reveal. Two metabolites of testosterone, estradiol and 5alpha-dihydrotestosterone (DHT), have been studied much less in human aggressive behavior. Estradiol might reduce androgenic effects and have a counterbalancing influence on aggression. DHT, again, has a much higher affinity than testosterone to androgen receptors, and there are indications that some of the effects of testosterone-mediating aggressive behavior occur after aromatization. Disregard of seasonal and circadian fluctuations in male testosterone production might be responsible for some of the inconclusive testosterone-aggression results. In addition, increasing age decreases both aggressive behavior and testosterone production in males. Cortisol has yielded conflicting results as a mediator in aggressive behavior. Both higher and lower levels have been reported in aggressive and abusive men. Finally, the acute and chronic effects of alcohol influence the steroid hormone levels in various ways. The present understanding of the etiology of aggression is still vague. It is clear that a multidimensional approach, combining both biological and psychosocial factors, will be necessary for the development of a more general concept of human aggression in the future.