People with depression have a higher risk if heart disease, and researchers now say it could be because emotional problems change their habits.

A team at the VA Medical Center in San Francisco studied more than 1,000 people with stable heart disease for nearly five years. It found that participants with depressive symptoms had a 50 percent greater risk of cardiovascular events such as a stroke or heart attack.

But when researchers adjusted the numbers for things known to help prevent heart problems, such as exercise levels, they found that depression was less of a factor. Because people with depression are less likely to follow diet, exercise and medication recommendations, their poor health behaviors increase the heart risk.

"These findings raise the hypothesis that the increased risk of cardiovascular events associated with depression could potentially be preventable with behavior modification, especially exercise," the authors of the study said.

In the study, 10 percent of people with signs of depression had a heart event every year, compared to 6.7 percent for those without.