Ovary Removal May Up Dementia Risk
Study Shows Estrogen May Help Protect Younger Women's Brains
Aug. 29, 2007 -- New research is raising important questions about the
protective benefits of estrogen on the brain and the long-term risks of
removing the ovaries before menopause.
Women in a 30-year follow-up study who had ovaries surgically removed before
menopause had nearly double the risk for developing age-related dementia later
in life. But the increased risk was not seen in women who had both ovaries
removed and were also treated with estrogen until at least age 50.
The study, published in the latest online issue of the journal
Neurology, suggests there is a "critical age window" for the
protective effect of estrogen on women's brains, says researcher Walter A
Rocca, MD, MPH, of the Mayo Clinic in Rochester, Minn.
"It is possible that estrogen has a protective effect on the brain and
that lack of estrogen due to ovary removal may increase a woman's risk of
developing memory problems," Rocca says in a news release.
Estrogen Protects Brain
The study included roughly 1,500 women who had one or both ovaries
surgically removed before age 50 and an equal number of women who did not have
The women were followed for an average of 27 years, during which time they
were interviewed to determine if they had developed memory problems and other
age-related cognitive issues.
Rocca and colleagues found that the younger the women were when they had
their ovaries removed, the more likely they were to develop dementia later in
life unless they received treatment to replace the estrogen their bodies were
no longer producing.
Of the 427 women in the study who had surgery to remove both ovaries prior
to age 49, only one out of five was also treated with estrogen therapy until at
least age 50.
These estrogen-treated women showed no increase in later dementia risk,
compared to women who still had their ovaries.
The doubling in risk seen in women who had both ovaries removed but did not
have estrogen replacement therapy until at least age 50 has important clinical
implications for younger women facing choices about ovary removal and estrogen
replacement following surgery, Rocca says.
A Shift in Thinking
Surgical removal of the ovaries, known as oophorectomy, can be performed as
a treatment for conditions such as ovarian cysts and endometriosis. But the
ovaries may also be removed to reduce a woman's risk of developing some
For premenopausal women no longer concerned about preserving their
fertility, past thinking had been that there was little downside to removing
the ovaries when a hysterectomy is performed to remove the uterus.
But that thinking is now changing, Rocca says, because of emerging
evidence suggesting that adequate estrogen prior to menopause protects against
heart disease, osteoporosis, and now dementia later in life.
"It is now clear that we need to weigh concerns about cancer against
concerns about these other diseases in decisions about the preventive removal
of the ovaries in women of this age," he tells WebMD.