Decreasing levels of gonadal steroids with aging are associated to an increase in cognitive, neurological and psychiatric disturbances. Estradiol is neuroprotective in animal models of neurodegeneration. However, the effects of hormonal replacement therapy on brain function in postmenopausal women are controversial. A possible alternative to hormonal replacement therapy is to increase local brain steroidogenesis, since experimental studies indicate that local estrogen formation in the brain is neuroprotective.