Risk Factors for Hot Flashes in Midlife Women

Maura K. Whiteman, Ph.D., Catherine A. Staropoli, M.D., Jamie C. Benedict, Ph.D., Christina Borgeest, B.A., Jodi A. Flaws, Ph.D.

In This Article

Smoking and Hot Flashes

Several studies indicate that cigarette smoking may be associated with risk of hot flashes ( Table 3 ).[5,13,14,15,18,72] Although some studies found no association between smoking and hot flashes[14] and others found an association only among those with low BMI,[5] most studies have found that smoking increases a woman's risk for any hot flashes[13,15,66,72] or for frequent or bothersome hot flashes.[18] Additionally, some investigators have reported an increased risk for hot flashes with increasing pack-years of smoking[13] or, to a lesser extent, with the amount currently smoked.[18] Although few studies examined the timing of smoking in relation to risk for hot flashes, there is some evidence that current smoking[18] or smoking at the time of menopause[13] increases a woman's risk for hot flashes, suggesting that smoking cessation may prevent or lessen the severity of hot flashes.

The precise mechanism by which smoking may alter the risk of hot flashes is unclear, but it may involve changes in estrogen metabolism. Several reports have noted lower active estrogen levels in smokers than in nonsmokers, and many animal studies indicate that smoking alters ovarian function.[73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90] Collectively, these reports suggest that smoking could alter estrogen metabolism by at least four distinct pathways.[73,80,81,82,83,84,85,86,87,88,89,90] First, cigarette smoking may directly deplete estrogen levels by interacting with the cytochrome P450 enzyme system, which is responsible for the metabolism of the chemicals in cigarette smoke as well as for the metabolism of estrogen.[73,74,75,76,83,84,85] Second, the chemicals in cigarette smoke may reduce the conversion of androgens to estrogens by inhibiting aromatase activity.[86] Third, the chemicals in cigarette smoke may reduce estrogen levels by inducing mutations or destroying ovarian follicles.[83,87,88,89] Fourth, the chemicals in cigarette smoke may indirectly alter estrogen metabolism by reducing body weight, as some studies indicate that smokers have a lower BMI or weight than nonsmokers and that low BMI or weight increases the risk of hot flashes.[5,90]

Smoking may be associated with hot flashes through mechanisms that are independent of estrogen metabolism, as several studies show that there are similar levels of estrogen in smokers and nonsmokers.[90,91,92,93] One way that smoking may alter hot flashes independent of estrogen metabolism may be via changes in androgen levels. Several studies have shown that smokers have higher levels of androgens than nonsmokers and that high androgen levels increase the risk of hot flashes.[90,94,95] Future studies that examine the mechanism by which smoking increases the risk of hot flashes will provide important clues about the mechanisms underlying the etiology of hot flashes in general.


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