Psychological and behavioural effects of endogenous testosterone levels and anabolic-androgenic steroids among males. A review.

The psychological and behavioural effects of endogenous testosterone levels and anabolic-androgenic steroids in males have been investigated for over 50 years in both clinical and nonmedical uses, including the influence of anabolic-androgenic steroids on the nervous system and neuromuscular expression as a mechanism for behavioural and ergogenic effects. The relationship between moods, behaviour and endogenous plasma testosterone levels, as well as anabolic steroids and corticosteroid administration has been studied, including psychological dependence, withdrawal effects, and major methodological issues. While a relationship between endogenous testosterone levels and aggressive behaviour has been observed in various animal species, it is less consistent in humans. It can be concluded that, although the use of exogenous anabolic-androgenic steroids may have psychological and behavioural effects in some patients and athletes, the effects are variable, transient upon discontinuation of the drugs, and appear to be related to type (17 alpha-alkalated rather than 17 beta-esterified), but not dose, of anabolic-androgenic steroids administered. The roles of genetic factors, medical history, environmental and peer influences, and individual expectations are likewise unclear. In general, the evidence at present is limited and much additional research will be necessary for a complete understanding of this relationship.