Estrogen Boosts Brain’s Abilities, Studies Show
Estrogen exerts a powerful influence on how well women can remember, pay attention and concentrate, with strong evidence emerging that the hormone can relieve symptoms of Alzheimer’s disease in post-menopausal women, researchers said Wednesday.
The new research, involving a range of human trials, animal studies and laboratory experiments, reveals that estrogen--commonly prescribed to offset the effects of menopause--plays a key role in how well the brain works.
The hormone appears to promote the growth of brain cells, fosters connections between them and enhances several types of mental activity, new research shows. One preliminary study suggested that estrogen may even offer greater protection to female brains from damage caused by stroke.
But the most dramatic finding is that estrogen appears to improve memory and attention in elderly women with Alzheimer’s disease, according to the first controlled study of how women with the disease responded to treatment with the hormone.
The collection of new research was made public Wednesday at a national meeting of the Society for Neuroscience.
“These studies have broad implications for Alzheimer’s disease and aging,” said C. Dominique Toran-Allerand, an expert on estrogen and the brain at Columbia University College of Physicians and Surgeons.
Estrogen, one of six steroid hormones in the body, is produced in the ovaries, fat tissues and the brain. Of the six, only estrogen appears to have growth-promoting properties in the brain, researchers said.
Although estrogen is commonly thought of as a female reproductive hormone, it is present in the brains of men and women. The male brain essentially converts the hormone testosterone into estrogen. However, researchers have focused on investigating its effects on the female brain because only women, due to menopause, undergo such a dramatic decline in the level of estrogen their body produces.
Estrogen alone, without progesterone, raises the risk of uterine cancer, and some studies show that hormone replacement therapy increases the risk of breast cancer. Estrogen therapy typically is not recommended for women with a history of certain clotting disorders and women with gallbladder or liver disease.
A number of studies have suggested that estrogen supplements can affect mood in post-menopausal women, prevent bone loss, promote the health of the heart and in some, prevent the onset of Alzheimer’s disease. Not until now did scientists have clinical proof of the hormone’s restorative effect on the human brain.
In a clinical study of a dozen female Alzheimer’s patients in their late 70s, researchers at the Veterans Medical Center in Tacoma, Wash., found that increasing the women’s levels of estrogen dramatically enhanced mental activity. The estrogen was administered for two months through a skin patch in doses no larger than normally prescribed as a supplement after menopause.
Within a week, the estrogen supplement almost tripled the women’s memory ability and doubled their concentration, as measured by a battery of standard neuropsychological tests. The women on a placebo showed no change.
The effects had not faded completely five weeks after the treatment was stopped.
“We found that the women who received estrogen had significant improvement,” said Dr. Sanjay Asthana, the geriatrics expert at the University of Washington School of Medicine who conducted the study. He cautioned that more, larger studies are necessary to gather more data.
Dr. Bruce McEwen, a brain expert at Rockefeller University in New York, was encouraged by Asthana’s study. Combined with others, he said, it shows a “consistent pattern” suggesting that estrogen can have a strong influence on the disease.
Other studies also strengthened the links between estrogen and the well-being of the brain:
* Estrogen may lessen stroke damage in women. In an animal study, researchers at the Johns Hopkins Medical Institute found “strikingly smaller” brain damage in female animals after strokes than in males; males had three times more brain damage than females with normal amounts of estrogen. In females with extremely low estrogen levels, the brain was indistinguishable from the males’.
* Estrogen may enhance the ability to perform fine motor movements. Researchers at the Oregon Health Sciences University in Portland found that young women with high estrogen levels were better able to perform rapid movements, such as keyboard exercises, than those with low estrogen levels. Estrogen might affect the basal ganglia, which moderates such behavior, they concluded. “Our data suggest that this effect is specific to women and sex hormones [and] may not affect this brain region and behavior in men,” the researchers said.
* Estrogen loss after menopause, rather than aging, may be responsible for increased non-Alzheimer’s-related forgetfulness and decreased attention span. Researchers at the Bowman Gray School of Medicine in Winston-Salem, N.C., determined in experiments with monkeys that lower estrogen levels had a pronounced effect on attention.
* Estrogen may promote connections between brain cells. Researchers at the National Institutes of Health, working with tissue cultures and laser-scanning microscopes, confirmed that exposure to estrogen enriches the complexity of the neural synapses that pass information from cell to cell within the brain.
“If the brain is deprived of estrogen, for whatever reason, there will be consequences,” Toran-Allerand said.
