WASHINGTON — Compared with uncaffeinated women, those who drank the equivalent of four or more cups of coffee a day are more likely to drink alcohol and smoke cigarettes and less likely to volunteer their time in church or community groups.

But a new study finds that well-caffeinated women have a key health advantage over their more abstemious sisters: They’re less likely to become depressed.

In the back-and-forth world of research on caffeine’s effects, the latest study suggests that women who get several jolts of java a day may do more than get a quick boost: Their mental health may see sustained improvement even as the physical stresses of aging accumulate.

Among a large population of women tracked for as long as 18 years each, the women who routinely consumed the highest levels of caffeine were 20 percent less likely than those who drank little to none to become depressed when they were nearing or in their 60s.

Coffee, which ounce-for-ounce delivers the strongest dose of caffeine, was most women’s pick-me-up of choice. And generally, the more caffeine a woman drank, the more likely she was to be in good mental health.

The study was published in the Archives of Internal Medicine.

“A small amount of coffee may keep you more active and more happy, and that may result in the long run in better brain health,” said Dr. Alberto Ascherio, the senior author of the study.

Cautioning that his group’s findings are preliminary, Ascherio added that they should ease concerns among female coffee addicts as they enter midlife; the average age of the participants was 63 years in 1996, when researchers began tracking the incidence of depression among the women.

“There’s no reason, from what we know, for people to cut back on their coffee consumption, unless, of course, it makes them feel bad,” said Ascherio, professor of epidemiology and nutrition at Harvard University’s School of Public Health.