According to the Los Angeles County Department of Public Health, stroke and coronary heart disease are the two leading causes of death in the county. The agency also notes that the rate of depression has doubled in the past decade. Now, a new study has found that chronic depression doubles the risk of stroke. The findings were published in the Journal of the American Heart Association.
The study authors note that a number of studies have reported that depression is associated with an increased risk of stroke; however, it is unclear whether that increased risk persists if the depression resolves. Therefore, they conducted a study to assess that issue. The researchers accessed data from the Health and Retirement Study (16,178 individuals who had not suffered a stroke at the study onset). The subjects were interviewed every two years from 1998 to 2010. Stroke and depressive symptoms were examined via self‐report of a physician diagnosis and a modified Center for Epidemiologic Studies ‐ Depression scale (high was three or more symptoms).
The investigators assessed whether symptoms of depression predicted stroke (1192 of the subjects suffered a stroke during the subsequent two years. They subjected the data to statistical analysis, adjusted for demographics, health behaviors, chronic conditions, and attrition (drop-out). The data was also adjusted for age (65 years or older), race or ethnicity (non‐Hispanic white, non‐Hispanic black, Hispanic), and sex.
The researchers found that, compared to individuals with low or no depression, stroke risk was increased among participants with stable high depression (2.14-fold increased risk) or resolved depression (1.66-fold increased risk). Stable high symptoms of depression predicted stroke among all groups with depression. Resolved symptoms of depression predicted increased stroke risk among women (1.86-fold increased risk) and non‐Hispanic white participants (1.66-fold increased risk).
The authors concluded that in this group, persistently high symptoms of depression were associated with increased stroke risk. The risk remained increased even if the symptoms of depression resolved over a two‐year period; they noted that this finding suggested a cumulative effect of depression on stroke risk.