Can estrogen help or hurt a woman's chances of developing Alzheimer's or another dementia?
Scientists are debating just that, and the concept of neuroprotective effects of the hormone remains controversial. Some research suggests it's protective, some that it's harmful depending on the age of the woman and the type of menopause (natural or surgical.)
Dr. Walter Rocca of the Mayo Clinic gives a concise description of "the timing hypothesis" in his abstract for Neurodegenitive Diseases, March 2010.
"Timing" refers to the time at which estrogen supplements are delivered--before, during or after menopause.
Rocca's team reviewed studies already published on the matter and, in some cases, reanalyzed data. They concluded that the neuroprotective effects of estrogen depend on age, type of menopause and the stage of menopause.
They found research suggesting that estrogen could be protective for women taking it in the premenopausal years, commonly before age 50; and also for women in the early postmenopausal phase (commonly from 50 to 60 years of age.) But they found recent trials that showed estrogen treatment initiated in the late postmenopausal phase (ages 65 to 79) led to an increased risk of dementia and cognitive decline.
A 2006 study in Menopause, the Journal of the North American Menopause Society, made the same suggestions--but also said more research is necessary.
The New York Times Magazine recently published a story called "The Estrogen Dilemma" in which the timing hypothesis was mentioned.