Undergoing Surgical Menopause Could Increase Your Risk Of Developing Alzheimer's

Can estrogen therapy after menopause protect your brain from diseases like Alzheimer’s? Nobody had thought of a possible connection between the two until now. A new study published in the journal Brain has however found that estrogen deprivation that follows surgical menopause may lead to a two fold increase in the cognitive decline of the brain. It may not only lead to dementia but also increase the likelihood of the patient developing neurological diseases like Alzheimer’s disease. The study was led by researchers working at the Medical College of Georgia at Georgia Regents University.

The experiment on rats

For their study, the researchers removed the ovaries and uterus of experimental rats in the laboratory. This led the rats to experience surgical menopause characterized by a sharp decline in their estrogen levels. Surgical menopause is the term used for a condition which mimics the characteristics of a natural menopause after the subject has undergone surgical removal of the ovaries along with or without the uterus.

The rats that had undergone the surgical procedure were either immediately put on low dose estrogen therapy, were put on estrogen therapy ten weeks after the procedure, or were never given estrogen. They were examined 10 weeks after removal of their estrogen producing ovaries.

The researchers created stroke like condition in the hippocampus region of the brain of the rats. Hippocampus is the center of memory and learning in the brain.

A part of hippocampus, called as CA3, which is normally resistant to stroke also showed signs of damage.

The researchers were astonished to observe that apart from the damage, the rats which received estrogen either late or never, exhibited an abnormal level of production of certain proteins which are characteristic of diseases of cognitive decline, like Alzheimer’s disease. The production of these proteins was especially marked in the CA3 region of the hippocampus. This part of the brain also became hypersensitive to the toxic beta amyloid proteins found in Alzheimer’s disease.

The researchers have linked the increased brain damage and excessive production of disease related proteins to the increased production of free radicals in the brain. They were able to reduce the extent of brain damage by suppressing the production of free radicals.

Researchers found that prolonged estrogen deprivation following surgical menopause increased the sensitivity of the brain to ischemic stress. This was especially true for the normally stress resistant CA3 region of the hippocampus.

Earlier Studies Have Also Linked Surgical Menopause To Early Cognitive Decline

Studies done in the past have also found a link between surgical menopause and cognitive decline. A study presented in the annual meeting of the American Academy of Neurology, held in San Diego, US in January 2013 also found an association between surgical menopause and decline in thinking and memory of the women. It found that women on hormonal replacement therapy showed a slower rate of decline of the cognitive functions.

For their study, the researchers, led by Dr. Riley Bove from the Harvard Medical School in Boston, enrolled 1,837 women between the ages of 53 and 100. All of these women were a part of the Rush Memory and Aging Project being carried out at the Rush University Medical Center, Chicago. 33% of these women had undergone surgeries which resulted in surgical menopause. The women were asked about their age at menarche and menopause, their menstrual cycles, and the details about their hormonal replacement therapy. All the participants of the study were also made to undergo several tests to measure their cognitive functions.

The researchers observed that the earlier the women were subjected to surgical menopause, the earlier and rapid was the decline in cognitive functions. The women who attained surgical menopause earlier performed badly in tests pertaining to concept and idea related memory, time and place related memory, and in tests related to overall thinking capabilities. The results were the same irrespective of the women’s age, smoking habits and education. These results were not seen in women who attained natural menopause. The brains of women who underwent surgical menopause also showed marked increase in the plaques associated with Alzheimer’s disease. However, the women who were put on hormonal replacement therapy soon after the surgical procedure showed a slower decline in their cognitive functions.

The study has opened the debate on whether hormonal replacement therapy has a protective effect against cognitive decline and whether women with surgical menopause should be put on long term hormone replacement?

Another study published in the journal Proceedings of the National Academy of Sciences in 2011 supports the protective action of estrogen on the brain. According to that study, prolonged deprivation of estrogen in aging rats led to a dramatic reduction in the number of estrogen receptors in the brain along with a reduction in the brain’s ability to prevent strokes. But the damage can be limited if estrogen replacement therapy is started shortly after the hormone level drops.

After surgical menopause, the unused estrogen receptors in the brain are eliminated. Starting estrogen replacement soon after the surgery can prevent this elimination. However, there is a critical window period for this. If hormonal replacement is started beyond this window period, it does not offer any protection to the brain. On the contrary, it may cause more damage as was seen in the Women’s Health Initiative study.

The Women’s Health Initiative study was a 12 years long study involving 161,808 women between the ages of 50 and 79. It was found in the study that the hormone replacement therapy increased the risk of stroke and other health problems. But it has been argued that the study involved women who were put on hormone replacement therapy much after they had attained menopause. This implies that the critical window period is very important if one wants to achieve the protective action of estrogen on the brain.

There is increasing evidence to conclude that surgical menopause is tied to increased risk of many chronic conditions like the coronary heart disease, stroke, and cognitive decline. Therefore, it is important to save the ovaries in women undergoing hysterectomy as far as possible. And in case removal of ovaries is mandatory, as in women suffering from conditions like breast or ovarian cancer, they should be considered for hormone replacement therapy at the earliest.