This makes sense, since serotonin helps carry messages from the hypothalamus - the part of the brain that controls body temperature - to the heart, blood vessels, and sweat glands.
Scientists don't understand why menopausal hormone declines make the hypothalamus go haywire, perceiving the body as too hot and ordering a cool-down. (Hormone supplements, the gold-standard flash therapy, have rare, serious side effects - thus the search for other options.)
Even less understood than the physiology, however, is the psychology.
Consider that hot flash frequency was cut by at least half for 36 percent of the women taking placebo. (Lexapro helped 55 percent who took it.)
And when all the women stopped taking pills, flashes promptly increased for the Lexapro group - but not the placebo group. Three weeks later, women were still benefiting from their fake therapy.
That provides "further evidence" of Lexapro's effects, Freeman and her study coauthors wrote last week in the Journal of the American Medical Association.
But it also suggests that for some women, resetting the thermostat is partly a matter of mind over matter.
"Whatever changed with the placebo, it didn't change back," said Freeman, a professor of obstetrics and gynecology at Penn. "I thought that was extremely interesting."
Lexapro maker Forest Pharmaceuticals may prefer to point out another interesting result: Side effects such as insomnia, dry mouth, and dizziness were more commonly reported by women taking placebo than the drug.
