Gonadal hormones, sex and behavior.

Gender differences have been demonstrated in several regions of the central nervous system (CNS) in animals and humans. These differences change with development and aging and are probably influenced by hormones. Gender differences have been demonstrated clinically in the prevalence of some mental disorders and responses to psychotropic medications. Gonadal hormones might be involved in these differences as well as in differential cognitive functions. The two genders also differ in the aging process. While it is well known that changes in the pituitary gonadal system influence the aging process in women, preliminary data described here demonstrate the association between pituitary-gonadal hormones and the aging process of sexual desire and activity in men. The changes in levels of gonadal hormones might contribute to the pathophysiology of dysphoric cyclic disorders and increased vulnerability to affective disorders in women. This vulnerability might be related to hormonal fluctuations over time as well as to alteration in internal oscillators and time-related functions.