Women who have their ovaries removed before menopause run a heightened risk of developing dementia or other mental problems later in life - unless they take oestrogen until age 50, a new study suggests.
Experts said the research needs to be confirmed by further study. However, the findings suggest premenopausal women should discuss this with their doctors when they consider ovary removal.
And if they decide to go ahead with surgery, they need to consider the risks and benefits of taking oestrogen until age 50, said Dr Walter Rocca, a Mayo Clinic neurologist and lead study author.
Hormone therapy has been linked to a greater risk of dementia and heart attacks when given to women after age 65.
Hormone therapy may protect
Recent research indicates that when given before menopause or just afterward, it does not raise heart attack risk and may protect against dementia.
The study did not include women who had ovaries removed as part of cancer treatment, and Rocca said the results do not apply to such women. The work was published Wednesday in the online edition of the journal Neurology.
Ovaries produce oestrogen. Rocca said the likeliest explanation of the study results, is that removing ovaries causes a sudden deficiency of that hormone, which in turn affects the brain.
Hundreds of thousands of women have their ovaries removed each year in the United States. In women around age 45, approaching menopause, ovaries are often removed during hysterectomies as a precaution against developing ovarian cancer.
In addition, some women at unusually high risk of developing ovarian cancer, have ovaries removed without hysterectomies, as do others who have ovarian problems like endometriosis.
Age is important factor
Women younger than 45 often take oestrogen after ovary removal because of symptoms like hot flashes and concerns about developing osteoporosis, noted Dr Nancy Chescheir of Vanderbilt University.
But older women who have the surgery are less likely to start oestrogen therapy, said Chescheir, who did not participate in the new research.
The new study found the risk of later mental impairment was higher when the surgery was done at younger ages. The research examined the fates of about 1 500 women who had one or both ovaries removed from 1950-87, and compared them to about 1 500other women.
Interviewers spoke with either the women themselves or somebody who knew them, asking about signs of memory impairment and any diagnosis of dementia or Alzheimer's disease.
Overall, the study found that women who had had one or both ovaries removed showed about a 50 percent increase in risk of the later mental problems.
A second study, which included about 2 300 women who had had the surgery and about 2 400 who had not, found about a 70 percent increased risk for a diagnosis of Parkinson's disease or Parkinson's symptoms like tremors.
That outcome was far less common than mental impairment, and experts said the evidence behind it was weaker than that provided in the mental-impairment paper.
The Parkinson paper finding is "not quite ready for prime time" in terms of affecting patient care, said Dr J. Manson, chief of preventive medicine at Harvard's Brigham and Women's Hospital. She was not involved with either study.
The mental-impairment paper suggests that a premenopausal woman without a family history of ovarian cancer who has to decide on whether to have her ovaries removed, should ask her doctor whether that step is really necessary, she said.
”It's very reasonable and important to have that conversation with her doctor," Manson said.
Chescheir noted that oestrogen therapy carries its own risks, such as a higher rate of blood clots and breast cancer, but that ovary-removal patients younger than 50 may want to have a serious discussion of that option after surgery. – (Malcolm Ritter, Sapa)
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