Older women are more likely to develop depression and remain depressed than older men but are less likely to die while depressed, contributing to a disproportionately high burden of depression among older adults, according to an article in the February issue of Archives of General Psychiatry.

Major depression affects approximately 1 percent to 2 percent of older adults living in the community, but as many as 20 percent experience symptoms of depression, according to background information in the article. These symptoms are more likely to affect older women than older men for reasons that are unclear.

Lisa C. Barry, PhD, MPH, of Yale University School of Medicine, New Haven, Conn., and colleagues evaluated a group of 754 individuals age 70 years and older (average age 78.4) beginning in 1998. At baseline and at follow-up assessments conducted every 18 months, participants were asked to provide demographic information, take cognitive tests and report any medical conditions. They also were screened for symptoms of depression during the previous week.

Over the course of the study, 269 (35.7 percent) of the participants were depressed at some point. Of those, 48 (17.8 percent) remained depressed during two consecutive time points, 30 (11.2 percent) at three points, 17 (6.3 percent) at four points, and 12 (4.5 percent) at all five. More women than men were depressed at each 18-month follow-up and women were more likely than men to experience depression at subsequent time points.

"Adjusting for other demographic characteristics, 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 authors wrote.

The findings were consistent over the four time intervals, providing strong evidence that depression is more persistent in older women than older men, the authors noted. This is surprising, because women are more likely to receive medications or other treatment for depression.

"Whether women are treated less aggressively than men for late-life depression or are less likely to respond to conventional treatment is not known but should be the focus of future research," the authors wrote. "In addition, nearly 40 percent of the depressed participants in this study were depressed during at least two consecutive time points, highlighting the need to initiate and potentially maintain antidepressant treatment after resolution of the initial depressive episode."