The Effects of Estrogen on Women's Health

Evidence is growing that estrogen may help protect women against Alzheimer's disease, although there are potential risks for estrogen therapy. Women only produce estrogen until menopause. In men, although their testicular production of gonadal hormones declines with increasing age, they still continue to convert testosterone into estrogen until the seventh decade of life, and their testicular function never ceased entirely. - making some researchers believe that this could give men a natural protection against Alzheimer's - and explained why women are twice as likely to develop the disease.

Over the next 20 years, 40 to 50 million women will pass through menopause. In the Western World, the median age of menopause is 50.8 years, but estrogen depletion in women often begins much earlier. Estrogen is involved in some 300 bodily processes. The constellation of withdrawal symptoms include, ubiquitous hot flashes, loss in bone density, loss of concentration, sleep disruption, mood orbits, heart disease and allergies. Estrogen is stored in fat cells. Heavier women may have an easier time going though menopause since their bodies have more stored estrogen to draw on as hormone production slows. From pre-menopause to post-menopause, estrogen levels drop about 12-fold.

What Is The Role of Estrogen?

Estrogen is the female steroid hormone which is produced in the ovary and which circulates in the blood stream. The specific proteins which bind to estrogen are distributed in the limbic brain, forebrain, hypothalamus, mid-brain and anterior pituitary, as well as in organs such as the ovary and uterus. Estrogen modulates the limbic brain controlled hypothalamo-pituirtary-ovarian function, and regulates cyclic release of estrogen from the ovary in women. Lower levels of estrogen act on neural function to bring the onset of puberty and to initiate ovarian cyclically. In the reproductive period, women ovulate periodically, and they are able to become pregnant and lactate. Once the ovary reaches the time of cessation of the cyclically, the ovary produces less estrogen and women enter the menopausal period. One of the major symptoms of menopausal women is dementia of Alzheimer type (DAT). The symptoms are an impairment of intelligence and performance (psychological symptoms); impairment of memory, language disintegration, disturbances of praxis, disturbance of gnosis (neurophychological symptoms); epileptic seizures, motor disturbance (neurological symptoms).

There are a number of mechanisms whereby replacement estrogen might improve cognitive function. Estrogen may act directly on choline acetyltransferase, the enzyme that synthesizes acetylcholine, which has been incriminated in the pathogenesis of Alzheimer's disease. (Bartus, Dean, Beer, & Lippa, 1982). In ophorectomized animal models, estrogen appears to stimulate neuronal regeneration and neurotropic growth factors and modulate long- and short-term synaptic function. Estrogen also induces reversible anatomical changes in nerve cells, including increased cell size in the ventromedial hypothalamus (Wong & Moss, 1992). In postmenopausal women, estrogen therapy may improve carotid artery blood flow which would imply a reduced risk of multi-infarct dementia and Alzheimer¹s disease (Gangar, Nyas, Crook, 1991). Other studies have shown that estrogen may promotes neurite growth and spine density in estrogen sensitive neurons of the brain. Because of this, it protects neuronal deaths. Estrogen have also been shown to promote synaptic plasticity in senile brain. Although further research is still needed, estrogen may provide beneficial neuroprotective effects on the neuron death in Alzheimer¹s patients.