Menopause and disorders of the central nervous system.

The cessation of ovarian estrogen production occurring around the time of menopause has the potential to influence central nervous system function, as well as a number of neurological disorders that affect women during midlife and old age, including memory loss and mild cognitive impairment, ischemic stroke, Parkinson's disease, and Alzheimer's disease. During midlife, there is observational evidence that episodic memory is not substantially affected by natural menopause or by use of estrogen-containing hormone therapy, but short-term clinical trial evidence suggests hormone therapy might benefit verbal memory after surgical menopause. Clinical trial data indicate that hormone therapy does not reduce, and may increase, stroke incidence. Parkinson's disease and Alzheimer's disease are the 2 most common neurodegenerative illnesses. Estrogen influences dopaminergic pathways within the central nervous system. However, available observational evidence is limited and inconclusive regarding any role of hormone therapy in influencing risk or symptoms of Parkinson's disease, a disorder of dopaminergic neurons. Finally, clinical trial data indicate that hormone therapy should not be initiated in the late postmenopause with the goal of improving memory, preventing cognitive decline, reducing dementia risk, or improving Alzheimer's disease symptoms. An important priority for clinical investigation is to determine whether hormone therapy used during the menopausal transition and early postmenopause has long-term effects on cognition or dementia risk. The critical window hypothesis as applied to Alzheimer's disease conjectures that effects of early hormone therapy might differ from those of hormone therapy initiated in the late postmenopause, but convincing evidence is yet to be obtained.