Harvard researchers have provided some of the most conclusive analysis to date indicating that depression can increase the risk of stroke.

Compiling data from 28 past studies involving more than 317,000 participants, researchers found that depression is associated with a 45 percent increase in the risk of stroke and a 55 percent increase in the risk of dying from a stroke.

“In previous literature, there was no conclusive evidence that depression could increase the risk of stroke,” said An Pan, lead author of the analysis and a research fellow at the Harvard School of Public Health.

The report was published Wednesday in the Journal of the American Medical Association.

Past studies have suggested an association between depression and the risk of stroke, but the results have not been consistent.

Pan’s team conducted a systematic review and analysis of the previous work.

“We thought that this study would be important for the community because depression is very common, and strokes are a leading cause of disability and death in this country,” Pan said.

In an earlier study, Pan found that antidepressant medication may be one factor to consider in the increased risk of stroke.

“There are a lot of inconsistencies and controversy regarding antidepressant medication,” he said. “Whether this medication has side effects that increase the risk of heart disease and stroke is unknown.”

Kathryn M. Rexrode, co-author of the analysis and an associate professor at Harvard Medical School and Brigham and Women’s Hospital, cautioned against ending medical treatment for depression out of concern that drugs may increase the risk of stroke. She recommended a holistic approach to treating depression.

“Physicians should be sure that they help depressed patients engage in healthy lifestyles, comply with medications, and get other cardiovascular risk factors under control—such as smoking, high blood pressure, cholesterol, and diabetes,” Rexrode said.

Pan said he hopes that depression will be included as a risk for stroke in the medical community so that patients with depression will be aware of the possible risks and monitor their symptoms accordingly.

He said that depressed individuals should also consider that behavior associated with depression, such as smoking and drinking, are also factors that increase the risk of stroke.

According to Pan, smoking increases the risk of stroke by 50 percent.

The researchers believe that future trials are necessary to determine treatments, if they exist, for helping depressed individuals reduce their risk of cardiovascular disease and stroke.