The behavioural effects of androgens in men
A series of studies are presented which attempt to answer specific questions concerning the androgen-behaviour relationship in the adult human male. A critical review of the literature revealed that the androgen-behaviour relationship in the human male has been poorly researched. In particular, unsatisfactory experimental methodology and inexact operational definitions of behaviour have been employed. In the studies presented in this thesis an attempt was made to specifically define dysfunctional states and to carefully monitor the resultant behavioural effects of androgen administration. In the hypogonadal man, a dose-dependent relationship was demonstrated for specific aspects of sexual functioning, in particular self-rated interest in sex and frequency of morning erections appeared to vary with androgen replacement dose. In the eugonadal man, intramuscular depot injections of testosterone were shown to be the best method of overcoming the homeostatic mechanisms and increasing circulating androgen levels in the blood. High dosage testosterone administration acted to increase the level of sexual interest of a group of men whose presenting complaint was loss of libido. This treatment, however, did not result in an increased frequency of sexual activity. High dosage testosterone administration had no behavioural effect, compared with placebo, in a group of eugonadal men presenting with erectile dysfunction. Androgen administration appeared to have a stimulatory effect on the nocturnal erections of a group of hypogonadal men, although androgen withdrawal resulted in differing rates of diminution of nocturnal erectile response. In contrast, androgen administration had no effect on the nocturnal erections of a group of eugonadal men presenting with erectile dysfunction. Androgen administration to hypogonadal and eugonadal men had a general lack of effect on a series of psychometric test scores, which measure various aspects of cognitive functioning and personality. (Previous investigators had proposed that these test scores were correlated with circulating androgen levels). A case study is presented, reporting the lack of behavioural effect of oral testosterone undecanoate administration in an institutionalised hypogonadal man who had previously responded very aggressively to testosterone injections. The implications of these experimental findings are discussed in relation to the results of previous studies.