The end of menstruation and of a woman's fertility. At menopause a woman's ovaries significantly reduce the amount of estrogen that they produce, causing numerous changes in her body's hormonal balance. These changes affect body systems in varied ways.
For many years researchers believed estrogen had a neuroprotective effect, helping to prevent development of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Some of this belief hinged on perceptions that women who experienced early menopause such as those who had total hysterectomy (surgery to remove the uterus and ovaries) had a higher rate of Parkinson's disease than women who experienced normal menopause, and as a result many doctors encouraged women to take hormone replacement therapy (HRT; estrogen and progesterone in combination) or estrogen replacement therapy (ERT; estrogen alone). numerous clinical research studies have not supported this hypothesis, however.
Most researchers now believe that there is little or no direct correlation between estrogen levels and such diseases, although there remains some debate and research continues in this area. other studies have demonstrated that long-term HRT or ERT significantly increases a woman's risk for certain forms of breast and uterine cancer, and it does not reduce her risk for heart disease according to the most recent evidence, causing doctors to revise recommendations about this approach.