Adjustment for physical activity was associated with a reduction in the strength of association between depressive symptoms and cardiovascular events.

When adjusted for other existing conditions and cardiac disease severity, depressive symptoms remained associated with a 31 per cent higher rate of cardiovascular events.

After further adjustment for certain health behaviours, including physical inactivity, there was no longer a significant association between depressive symptoms and cardiovascular events. Physical inactivity was associated with a 44 per cent greater rate of cardiovascular events, after adjusting for various factors.

The researchers noted that patients with depressive symptoms are less likely to adhere to dietary, exercise, and medication recommendations, and poor health behaviours can lead to cardiovascular events.

"These findings raise the hypothesis that the increased risk of cardiovascular events associated with depression could potentially be preventable with behaviour modification, especially exercise. Given the relatively modest effects of traditional therapies on depressive symptoms in patients with heart disease, there is increasing urgency to identify interventions that not only reduce depressive symptoms but also directly target the mechanisms by which depression leads to cardiovascular events," wrote the authors.

The study was published in the latest issue of JAMA.