Good Eggs: Ovaries Aid the Brain

Corrected 8/31/2007: An earlier version of this article incorrectly reported that women whose ovaries were removed before menopause had almost twice the risk of later developing dementia or conditions like Parkinson's. The overall increase in risk was about 50 percent, though the younger the woman was at the time of the surgery, the greater her risk of later neurological problems.

Timing matters.

That's the message coming from study after study on estrogen; the hormone can have very different—even opposing—effects on the heart, for example, depending on when in a woman's life she takes it. Research published this week in the journal Neurology found age may also play a role in the complex relationship between estrogen and neurologicalfunction. To unravel the issue, U.S. News talked with Walter Rocca, who led the new research and is an epidemiologist and neurologist at the Mayo Clinic in Rochester, Minn.

Your research showed that women whose ovaries were removed before menopause had a 50 percent higher risk, compared with women who kept their ovaries, of later developing dementia or conditions like Parkinson's. And that risk was even higher for the women who were youngest at the time of surgery. What does all that mean for patients?

We should be much more careful about when we do prophylactic oophorectomies [removal of ovaries for prevention of cysts or cancer]. Many fewer should be done. In the past, there wasn't enough evidence that it led to negative outcomes, but now we know there's an impact on the heart, on hip fractures, and now on neurological disorders.

Aren't women whose ovaries are removed at a young age routinely given estrogen therapy?

We were amazed to find that only about 60 percent of women with both ovaries removed received some kind of treatment, and only about 21 percent took the treatment all the way to age 50. It can be difficult to make a commitment [to getting treated] for 10 years or so.

Your study focused on women who'd had their ovaries removed. But your findings are also relevant to other aging women, right?

Absolutely. It adds new evidence to the so-called age-dependent or time-window effect, where something given at one age is protective and beneficial [but] at another age it's clearly harmful. [A major study called] the Women's Health Initiative has shown pretty much [indisputably] that initiating estrogen therapy late in life is harmful. The question is whether—if it's initiated earlier—it's helpful.

When you say "earlier," what ages are you thinking of?

As of today, the period between 50 and 65 remains uncertain. Nobody knows if the benefit/risk balance is positive. There's a hint, and some hope, that estrogen may be useful between 50 and 60, but for now it's only hope.

So what's a woman in that age group to do?

It's very risky to have a one-size-fits-all approach or to say that estrogen is all good or all bad. It has to be discussed individually [with a doctor]. You need to take into account family history and other risk factors. The recommendation hasn't changed: Hormones are advised only for short-term use around menopause, for symptoms, at the lowest effective dose.