Public Release: 

Long-term depression may double stroke risk for middle-aged adults

Study finds stroke risk remains elevated even after depressive symptoms improve

Harvard T.H. Chan School of Public Health

Boston, MA -- Adults over 50 who have persistent symptoms of depression may have twice the risk of stroke as those who do not, according to a new study led by researchers at Harvard T.H. Chan School of Public Health. Researchers found that stroke risk remains higher even after symptoms of depression go away, particularly for women.

The study will be published online May 13, 2015 in the Journal of the American Heart Association.

"This is the first study evaluating how changes in depressive symptoms predict changes in stroke risk," said lead author Paola Gilsanz, Yerby Postdoctoral Research Fellow at Harvard Chan School. "If replicated, these findings suggest that clinicians should seek to identify and treat depressive symptoms as close to onset as possible, before harmful effects on stroke risk start to accumulate."

The study looked at health information from 16,178 men and women ages 50 and older participating in the Health and Retirement Study between 1998 and 2010. Participants were interviewed every two years about a variety of health measures, including depressive symptoms, history of stroke, and stroke risk factors. There were 1,192 strokes among participants during the study period.

Compared to people with low depressive symptoms at two consecutive interviews, those with high depressive symptoms at two consecutive interviews were more than twice as likely to have a first stroke. Stroke risk remained elevated even among participants whose depressive symptoms went away between interviews, particularly for women. Those with depressive symptoms that began between interviews did not show signs of elevated stroke risk. Participants younger than 65 had greater stroke risk linked to their depressive symptoms than older participants with depressive symptoms.

The researchers suggest that depression may influence stroke risk through physiological changes involving accumulation of vascular damage over the long term. Damage may also be incurred indirectly through depression's effect on health behaviors, including increased risk of smoking and physical inactivity.

"Because this is the first study to take this approach, we need replication of findings in independent samples, with people of different age groups, and exploring different reasons that depressive symptoms get better," said senior author Maria Glymour, associate professor in the Department of Epidemiology and Biostatistics at the University of California, San Francisco, who worked on the research while at Harvard Chan School. "The surprising results make such replications even more urgent."

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Other Harvard Chan authors involved in the study include Eric Tchetgen Tchetgen, associate professor of biostatistics and epidemiologic methods, Laura Kubzansky, professor of social and behavioral sciences, and Ichiro Kawachi, John L. Loeb and Frances Lehman Loeb Professor of Social Epidemiology.

The HRS (Health and Retirement Study) is supported by the National Institute on Aging (NIA U01AG009740) and is conducted by the University of Michigan. Funding for this study was provided by Eunice Kennedy Shriver National Institute for Child Health and Human Development at NIH (R24HD041023 to Capistrant); the National Institute of Neurological Disorders and Stroke at NIH (T32 NS048005 to J.R. Marden); the National Heart, Lung, and Blood Institute at NIH (1F31HL112613 to Gilsanz); the National Institute of Mental Health at NIH (1RC4 MH092707 to Walter, Kubzansky, and Glymour); the Initiative for Maximizing Student Development (5R25GM055353 to Gilsanz); the National Institute on Aging (R21 AG03438502); the American Heart Association (grant 10SDG2640243 to Glymour and Gilsanz and 09PRE2080078 to Capistrant) and National Institute of Allergy and Infectious Diseases at NIH (grants AI113251 and AI104459 to Tchetgen Tchetgen) and National Institute of Environmental Health Science (grant AI113251 to Tchetgen Tchetgen).

"Changes in Depressive Symptoms and Incidence of First Stroke Among Middle-Aged and Older US Adults," Paola Gilsanz, Stefan Walter, Eric J. Tchetgen Tchetgen, Kristen K. Patton, J. Robin Moon, Benjamin D. Capistrant, Jessica R. Marden, Laura D. Kubzansky, Ichiro Kawachi, M. Maria Glymour, Journal of the American Heart Association, online May 13, 2015.

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Harvard T.H. Chan School of Public Health brings together dedicated experts from many disciplines to educate new generations of global health leaders and produce powerful ideas that improve the lives and health of people everywhere. As a community of leading scientists, educators, and students, we work together to take innovative ideas from the laboratory to people's lives -- not only making scientific breakthroughs, but also working to change individual behaviors, public policies, and health care practices. Each year, more than 400 faculty members at Harvard Chan teach 1,000-plus full-time students from around the world and train thousands more through online and executive education courses. Founded in 1913 as the Harvard-MIT School of Health Officers, the School is recognized as America's oldest professional training program in public health.

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