Major depression is recognized as a possible development after a cerebrovascular accident, or stroke, but there is less familiarity with depression that may precede and contribute to the onset of stroke. A meta-analysis of depression and the risk of stroke from 28 studies involving more than 300 000 participants in the September 21 issue of JAMA supports this association; adding stroke to such other conditions as diabetes, hypertension, and cardiovascular disease that occur with increased incidence in patients with depression.
With almost 8500 reported stroke outcomes in the studied populations, there was a positive association (hazard ratio, >1.00) of depression with total stroke and, when differentiated, with ischemic and fatal stroke. Although the analysis did not associate non-fatal and hemorrhagic stroke with depression, the investigators suspect this reflects too few studies identifying these stroke types.
The investigators calculated the absolute risk of stroke occurring per 100 000 individuals with depression to be 106 cases for total stroke, 53 cases for ischemic stroke, and 22 cases for fatal stroke. With an estimated 9 percent (21 million) of persons in the US currently meeting criteria for depression, the investigators project that 273 000 stroke cases (3.9 percent), "could be attributable to depression."
Depression may contribute to stroke through a number of mechanisms, the investigators posit: through the neuroendocrine, immunologic, and inflammatory effects now being elucidated; through accompanying poor health behaviors such as inadequate nutrition and smoking; and through comorbidities such as diabetes and hypertension.
Most of the studies included in this meta-analysis lacked information on depression treatment and antidepressant medication use. In addition to calling for more studies to explain underlying mechanisms of the association between depression and stroke, the investigators indicate, "the role of depression treatment in modulating subsequent risk of stroke needs to be studied further."