Mar. 23 --
FRIDAY, June 29 (HealthDay News) -- Estrogen injections might help keep women's minds sharp as they age, a new study of female monkeys suggests.
For the study, published in this week's online issue of the Proceedings of the National Academy of Sciences, researchers at Mount Sinai School of Medicine, in New York City, removed the ovaries of four distinct groups of female rhesus monkeys. One group included old monkeys that received estrogen; a second group included old monkeys that did not receive estrogen; and there were two other groups of young monkeys that either received or did not receive estrogen.
Removing the monkeys' ovaries induced menopause. The older monkeys had their ovaries removed around the time of perimenopause -- before the onset of full menopause.
Estrogen treatment involved pure estradiol injections every 21 days. The researchers periodically tested the monkeys on a series of cognitive tasks over the course of more than two years.
Older monkeys that were treated with estrogen performed almost as well as the younger monkeys on the mind-challenging tests, the researchers reported, while untreated older monkeys showed dramatic cognitive declines.
Surprisingly, the younger monkeys performed equally well whether or not they were treated with estrogen.
The study also found that the estrogen-treated monkeys showed brain changes associated with the prevention of cognitive decline. On the other hand, the older untreated monkeys showed no signs of these changes.
The findings suggest that the debate over whether hormone replacement therapy is beneficial may not be over, according to study co-author John H. Morrison, dean of basic sciences and the graduate school of biological sciences at Mount Sinai.
"There's been a great deal of confusion as to whether estrogen helps or harms postmenopausal women, and our findings tell us is that there is a very critical window of opportunity in which estrogen may be helpful," he said in a prepared statement.
He noted that this critical window could be around the time of perimenopause, when estrogen may be able to protect the brain from cognitive decline.
"Estrogen levels decline in old age, so the brain may need a certain amount of circulating estrogen to remain supple. Timing may be everything," Morrison said.
The U.S. National Institute of Child Health & Human Development has more about menopause.
SOURCE: Mount Sinai Medical Center, news release, June 25, 2007