A study of more than 16,000 women ages 40-55 has found that common symptoms of menopause differ by ethnicity, socioeconomic status, and lifestyle factors.
The research is from the first phase of the Study of Women's Health Across the Nation (SWAN), a nationwide undertaking designed to study midlife changes and their effects on the risks of several types of disease. The research is published in the September 1 issue of the American Journal of Epidemiology.
"This is one of the largest multi-ethnic studies of demographic and lifestyle factors associated with symptom reporting in midlife women, and the findings have potentially important preventive implications," said Ellen B Gold, professor of epidemiology and preventive medicine at UC Davis School of Medicine and Medical Center and lead author of the study.
Women were asked about seven symptoms: hot flashes or night sweats, urine leakage, vaginal dryness, joint stiffness/soreness, heart pounding or racing, forgetfulness, and difficulty sleeping.
All symptoms except forgetfulness were less frequently reported in Japanese and Chinese women than other ethnic groups. African American women were more likely to experience hot flashes or night sweats, vaginal dryness, and forgetfulness; for example, 45 percent of African-American women reported experiencing hot flashes or night sweats two weeks before participating in the UC Davis study, compared with 31 percent of Caucasians. Hispanic women were more likely to report urine leakage, vaginal dryness, heart pounding, and forgetfulness.
The ethnic differences, said Gold, raise some questions. "Are these just reporting differences, or are they related to factors in the women's lives, like diet or other lifestyle factors?" Gold said. "Some literature suggests hormonal levels differ by ethnicity. Is this true and could it result in different symptoms?"
SWAN has studies under way in an attempt to answer some of these questions; in the meantime, said Gold, "Health care providers should at least know there are differences in reporting, and should be aware of them when they're questioning women about symptoms and possible therapies."
Researchers also found that women were more likely to experience symptoms if they were older, had a lower educational level, had difficulty paying for basic needs, smoked, got less exercise than their peers, or had a high body mass index. (Body mass index is a ratio of weight to height squared that is useful for determining the degree of obesity.)
Compared with women 40-43, older women were more likely to report hot flashes and night sweats, vaginal dryness, and forgetfulness. Women with less than a high-school education were more likely to report forgetfulness, heart pounding and hot flashes or night sweats. Those who said it was "somewhat hard" or "very hard" to pay for their basic needs were more likely to report all the symptoms asked about in the study, compared with women who said it was not hard to pay for basic needs.
Lifestyle factors also affected symptoms. Compared with women who had never smoked, women who had smoked in the past were still likely to report many symptoms, including hot flashes, urine leakage, stiffness or soreness of the joints, heart pounding, and forgetfulness. Those who currently smoked at least a pack a day were more likely to report difficulty sleeping, hot flashes, urine leakage and stiffness or soreness of the joints.
Women who believed they got less exercise than other women of the same age were more likely to experience all symptoms. Compared with women who had a body mass index (BMI) between 19 and 27, women with BMIs below 19 (less than 105 lbs. for a 5 ft. 4 in. woman) were more likely to have difficulty sleeping.
In the UC Davis study, obese women — those with BMIs above 27 — were more likely to experience urine leakage, joint stiffness or soreness, and hot flashes or night sweats; however, obesity has been associated with fewer hot flashes in most studies.
"The theory is that women who are heavier produce more of a type of estrogen called estrone in their fat," Gold said. "We would expect that these women would have fewer hot flashes, which are thought to be caused by low estrogen levels. We didn't show that, but the increases in symptom reporting were not large. I think the relationship between estrogen levels and hot flashes is probably more complicated than we think."
More than 3,000 women — a subset of the 16,000 women surveyed in this study— are being followed long-term in more detail. Future SWAN research includes the effects of diet, alternative therapies, and physical activity on symptom reporting, hormone levels, and other changes. Then, Gold said, researchers will examine how hormone changes and other midlife changes relate to the risk of other conditions, such as cardiovascular disease and osteoporosis.
SWAN is funded by the National Institute on Aging and the National Institute on Nursing Research.