People with long-term depression have an increased risk of suffering a stroke, a new study suggests.

Furthermore, this risk of stroke may remain for some time even if symptoms of depression are reduced.

US researchers looked at over 16,100 people aged 50 and older who took part in a 12-year study about depression and stroke. During this time, the participants were interviewed every two years about their health.

Over the course of the 12 years, almost 1,200 strokes were recorded.

The study found that people who were highly depressed at two consecutive interviews were more than twice as likely to suffer a stroke compared to those who were not depressed.

Those who had depression during their first interview, but not their second, also had a 66% increased risk of suffering a stroke. These findings suggest that even if treatment for depression works, the risk of suffering a stroke may still remain, at least for some time.

However, people who had recently developed depression did not appear to have an increased risk of suffering a stroke.

"Looking at how changes in depressive symptoms over time may be associated with strokes allowed us to see if the risk of stroke increases after elevated depressive symptoms start or if risk goes away when depressive symptoms do. We were surprised that changes in depressive symptoms seem to take more than two years to protect against or elevate stroke risk," noted the study's lead author, Paola Gilsanz, of Harvard University.

The researchers added that while it is now clear that depression ‘strongly predicts stroke on par with many other major stroke risk factors', it is still unclear why this happens and more research is needed.

For more information on depression, see our Depression Clinic here