The study of the effects of gonadal hormones in the brain focussed mainly on reproductive actions for a long time. Meanwhile, however, it is well known that gonadal hormones, in particular estrogens, also have neuroprotective and psychoprotective properties. They modulate many brain functions such as cognitive functions, pain regulation, motor coordination, and epilepsy, as well as affective and psychotic disorders, to name just a few. In fact, during the past few years we have experienced a major change in our understanding of the endocrinologic aspects of psychiatric disorders....