Older women are more prone to depression and are more likely to remain depressed than older men, according to a new study by Yale School of Medicine researchers in the February Archives of General Psychiatry.

The Yale team also found that women were less likely to die while depressed than older men, indicating that women live longer with depression than men. This factor, along with the higher likelihood of women becoming depressed and remaining depressed, collectively contribute to the higher burden of depression among older women.

Major depression affects about one to two percent of older adults living in the community, according to the authors, but as many as 20 percent experience symptoms of depression. It is unclear why symptoms of depression affect older women more than older men.

Lead author of the study, Lisa C. Barry, associate research scientist in the Yale School of Public Health, and colleagues evaluated a group of 754 individuals age 70 and older from 1998 to 2005. Participants were asked to provide demographic information, take cognitive tests and report any medical conditions at the start of the study and at follow-up assessments conducted every 18 months. Barry and her team screened participants for depression symptoms—such as lack of appetite, feeling sad or sleep problems—exhibited during the previous week.

During the study, 35.7 percent of the participants were depressed at some point. Of those, 17.8 percent remained depressed during two consecutive time points, 11.2 percent at three time points, 6.3 percent at four points and 4.5 percent at all five time points. More men than women were depressed at each 18-month follow-up and women were more likely than men to experience depression at subsequent time points. Women had a higher likelihood of transitioning from non-depressed to depressed, and a lower likelihood of transitioning from depressed to non-depressed or death.

The team found that nearly 40 percent of the depressed participants were depressed during at least two consecutive time points. “This highlights the need to initiate and potentially maintain antidepressant treatment after resolution of the initial depressive episode,” said Barry, who is a Brookdale Leadership in Aging Fellow.

“Our findings provide strong evidence that depression is more persistent in older women than older men,” said Barry. “We were surprised by this finding because women are more likely to receive medications or other treatment for depression. Further studies are needed to determine whether women are treated less aggressively than men for late-life depression, or if women are less likely to respond to conventional treatment.”

Other authors on the study included Heather G. Allore, Zhenchao Guo, Martha L. Bruce, and Thomas M. Gill, M.D.

The study was supported by grants from the National Institute on Aging. It was conducted at the Yale Claude D. Pepper Older Americans Independence Center.