USAToday
Your Health: Hot flashes are still an 'enigma'
If menopause has a defining symptom, it's the one-woman heat wave: the hot flash.
But if women of a certain age poll their friends, they'll learn something researchers have now firmly documented: We are not all in this together. Hot flashes are common but not universal. And they are much worse for some women than for others.
It's "one of the great enigmas of women's health," says Wulf Utian, founder of the North American Menopause Society in Cleveland. "A third of women don't have any, a third have a problem but it's tolerable, and a third are miserable."
So for every woman who sweats through sleepless nights, ruins clothes and curses every steaming wave of facial heat, another gently fans herself and sips ice water, while yet another wonders what all the fuss is about. But which women are which? A decade ago doctors could offer little but hunches and opinions. Thin women were thought to suffer most. Asian women were thought practically immune. And women still overheating many years after their last periods were considered rare.
All of that now appears at least partly wrong. Much has been learned since 2002, when a large study raised concerns about long-term use of hormones used to treat hot flashes — and scientists got more interested in learning who needed help and what other approaches might work.
Among findings: Heavy women, not thin ones, seem to suffer most. In fact, overweight women who lost weight got significant relief from hot flashes in one recent study.
"For a long time, it was assumed that being overweight would actually be protective," says study author Alison Huang of the University of California-San Francisco. Body fat produces some estrogen, theoretically making up for supplies no longer coming from a woman's ovaries. Plummeting estrogen levels are thought to trigger hot flashes.
But now studies consistently show more hot flashes in heavy women, at least during perimenopause, the years leading up to the last period, says Rebecca Thurston, a researcher at the University of Pittsburgh. "Body fat may act as a kind of blanket about your body," she says.
It is possible that extra weight helps some postmenopausal women and that doctors who once said thin women suffered more were describing older patients, not younger women in the throes of the menopausal transition, says Ellen Gold, a researcher at the University of California-Davis.
Thurston and Gold are among researchers following a large, diverse group through that transition in the federally funded Study of Women's Health Across the Nation (SWAN). The data show hot flashes become more common as women move from regular menstrual periods to few, then none. They eventually affect a majority in every racial and ethnic group. And many women still report hot flashes years after their periods end, Gold says.
Meanwhile, SWAN and other studies have linked hot flashes to several risk factors beyond weight:
• Race. African-American women report more hot flashes than white and Hispanic women, who report more than Asian women. Biology and culture could both play roles, researchers say.
• Anxiety. Women who are highly anxious before symptoms start have more trouble, Gold says.
• Smoking. Smokers also go through menopause earlier.
Not clear: the influence of diet, caffeine, alcohol and exercise. Subgroups of women may benefit from different interventions, Gold says: "Twenty years from now, we may know who they are."
