Monday, October 13, 2014

Estrogen, hot flashes, and brain health

The aim of most hormonal treatments for endometriosis is to decrease estrogen. Over time this is not a good approach for our health in general. Here we see the affect of lowered estrogen in perimenopausal, menopausal women:

"Hot flushes, the classic symptom of menopause, are experienced by up to 85% of perimenopausal women.[11] (Perimenopause begins several years before menopause, when ovarian function starts to decline, and continues for several years after menopause, until ovarian function has reached its nadir.) A hot flush consists of a sudden sensation of heat in the upper body, often followed by perspiration and a chill. Peripheral vasodilation, tachycardia, decreased skin resistance, and sweating have all been documented to occur during a hot flush. Although poorly understood, the episodes certainly originate in the brain, most likely as a direct response to hypoestrogenism in the thermoregulatory center of the hypothalamus.[12]                     
It now appears that hot flushes are not merely symptoms of low estrogen levels; they may themselves lead to other neurologic problems. In oophorectomized women, hot flushes have been directly correlated with memory impairment.[13] In addition, single proton emission computed tomography (SPECT) of healthy menopausal women revealed decreased cerebral blood flow during hot flushes.[14] The greatest change occurred in the hippocampus, a center for memory and cognition. Regional patterns of cerebral blood flow during hot flushes resembled those characteristic of Alzheimer's disease. ERT resolved the hot flushes and restored normal patterns of cerebral blood flow.
Based on this evidence, reproductive biologists have hypothesized that hot flushes contribute to degenerative or aging changes in the brain.[15] Frequent vasoconstrictive episodes might lead to cerebral ischemia and free radical formation. The resulting damage may be analogous to that seen in the coronary arteries with plaque formation. The population of healthy neurons might be reduced, particularly in the hippocampus, leaving the brain with impaired ability to tolerate the neurodegenerative processes of aging and Alzheimer's disease.

Even in healthy older women, brain volume begins to decline as estrogen levels fall in the perimenopausal period.[16] This atrophy occurs particularly in the hippocampus and parietal lobe, areas primarily associated with memory and cognition. A similar loss in brain volume does not begin in men until a decade later (around age 60), most likely because male sex hormone production declines much more gradually with age. In fact, because of aromatization of testosterone to estrogen, men over the age of 60 have approximately three times more circulating estradiol than women of a similar age.[17]
In women, these cerebral changes may contribute to the frequent perimenopausal complaints of decreased mental clarity and short-term, verbal memory problems (see Table 1).[18] Studies of the effects of ERT on cognitive symptoms have generated inconsistent results, perhaps because dropouts and nonparticipants are more likely to be cognitively impaired.[19] A recent meta-analysis yielded only weak evidence that ERT improves cognition and prevents dementia.[20] However, many research groups have found a significant association between ERT and cognition, particularly in the area of verbal memory. For example, in one study of 727 postmenopausal women, history of estrogen use was associated with significantly higher scores on verbal memory and abstract reasoning tests.[21] "