Pointing the way toward lowering dementia risk in women

By Sharon Oosthoek

Dr. Mary Tierney is fascinated by the complex links between menopause and memory, an area of research she believes may one day help lower the risk of dementia in women.

"We have to open up the door and study this a bit more," insists the Toronto neuropsychologist and professor at the University of Toronto.

While doctors have long known women are more likely than men to get dementia, Tierney's research suggests some promising possibilities for treatment.

Sitting in her office at the Sunnybrook Health Sciences Centre, Dr. Tierney grabs a notepad and begins sketching a graph to illustrate.

A woman's estrogen level declines after menopause, plummeting in some, gradually dissipating in others, she explains.

That's important because the region of the brain linked to memory, the hippocampus, is chock full of receptors for estrogen. In fact, the hormone is one of the keys to how the hippocampus functions. As estrogen declines, so does a woman's memory.

Men, on the other hand, don't experience the same drastic decline in estrogen in their brains. Their sex hormone, testosterone, is converted in the brain into estrogen, and since testosterone doesn't significantly drop as men age, their hippocampus keeps working.

The part that gets Dr. Tierney excited is that it may be possible to safely boost estrogen in aging women, keeping their hippocampus in working order.

She recently wrapped up a clinical trial that showed a particular combination of estrogen-progesterone prevented a decline in verbal recall in older women who didn't have dementia. On the other hand, it didn't have as much of an effect on women whose cognition had already declined, as measured by their ability to verbally recall certain words.

Declines in verbal recall are often an early signal that a person will develop Alzheimer's disease later in life.

Tierney's findings are especially good news, following on the heels of an American trial of estrogen-progesterone that was abruptly cancelled in 2002 after it was found to increase the risk of breast cancer.

Dr. Tierney not only used a different type of estrogen-progesterone; the women in her trial used it cyclically and not continuously, as in the American study. She suspects that this, plus the fact that it was a smaller trial and the women were older, is why no women developed breast cancer during the two-year trial.

While she's not ready to recommend her hormone replacement therapy to prevent memory loss until the findings have been replicated, she is buoyed by the possibilities for treating women before they start to experience memory problems.

"Estrogen is not going to protect neurons that are already non-functioning," cautions Dr. Tierney. "We really should be treating women before they begin to experience serious memory problems."

The Alzheimer Society of Ontario helps support The Alzheimer Society Research Program, which offers grants and training awards for biomedical and psychosocial research at Sunnybrook Health Sciences Centre, and other research centres. The program is a collaborative effort among the Alzheimer Society of Canada, its provincial affiliates, partners, and donors.

Sharon Oosthoek is a Toronto-based freelance writer.

Photo of Dr. Mary Tierney above by John Rennison, Hamilton, ON.

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