But psychological distress did not significantly increase the risk for non-fatal stroke and there was no link between mood disorders and increased risk for transient ischemic attacks, or TIAs – the so-called mini-strokes that are sometimes precursors to major strokes.
The findings are from the latest report of an on-going study of middle-aged men who live in an area of South Wales, says Margaret May, MSc, lead author of the study.
“The study is one of the largest and best-designed studies that link depression to mortality,” says Robert M. Carney, Ph.D., professor of medical psychology at the Washington University School of Medicine in St. Louis. Carney co-authored an editorial that accompanies the Caerphilly Study results.
The Caerphilly Study included men who were registered to vote in Caerphilly. The men were asked to volunteer for the study of cardiovascular disease and related outcomes. The latest report is based on phase II of the study and includes 2,124 men aged 49 to 64 who were recruited between 1979 and 1988.
In a 30-item General Health Questionnaire, used to measure psychological distress, 22 percent of the men had test scores that indicated mood disorders. Detailed medical histories, smoking history, as well as height, weight, and blood pressure data were also collected. Each man underwent heart testing with an electrocardiogram. The men were then followed for 14 years, during which time the researchers collected data on the incidence of stroke.
During follow-up, 137 strokes occurred, including 17 fatal strokes. In general, men who had strokes were older, heavier and had higher blood pressure levels than men who didn’t have strokes. The men who had strokes were also more likely to be current smokers and to have at least one other chronic disease.
When May and her colleagues analyzed psychological profile data, they found that “the men who had strokes also showed a tendency to report more symptoms of anxiety and depression.” Moreover, a history of psychological distress was associated with a 3.36 relative risk for fatal stroke and a 1.25 relative risk for non-fatal stroke. The relative risk for TIA was 0.63. When the findings were adjusted for other risk factors, such as smoking and high blood pressure, the relative risk for fatal stroke declined to 2.56.
There also was a graded association so that as depression and anxiety worsened, the risk for fatal stroke increased, says May.
Carney has been studying the influence of depression on risk for heart attacks and says the new stroke findings “are similar to our work with myocardial infarction: an increased risk for fatal events but little or no increased risk for non-fatal events.”
He cautions that more studies are needed to pinpoint the mechanism by which mood contributes to cardiovascular health, but adds there are several likely explanations. “Depressed people often don’t take medicines as prescribed so some of the men may not be taking medicines for high blood pressure, thereby increasing their risk for stroke,” he says.
Moreover, research demonstrates an association between depression and anxiety and changes in the autonomic nervous system, which regulates heart rate and the contraction of blood vessels. Those changes “may produce alterations that contribute to the severity of stroke or heart attack,” says Carney.
But even without a precise explanation for the findings, Carney says the report is a wakeup call for physicians and patients. Depression and anxiety are often downplayed by physicians who fail to ask about psychological health and patients who are reluctant to discuss depression. “These findings suggest that ignoring depression and anxiety is probably not good medical practice,” he says.
Carney adds that psychological health should “be evaluated the same way we evaluate any medical risk factor – such as high blood pressure or smoking.”
Stroke is the third leading cause of death in the United States, ranking behind diseases of the heart and cancer. Each year about 600,000 people suffer a stroke, and every 3.1 minutes someone dies of stroke in the United States according to the American Heart Association’s 2002 Heart and Stroke Statistical Update.
May’s coauthors were Peter McCarron, MFPHM; Yoav Ben-Shlomo, MFPHM; George Davey Smith, DSc; Peter Elwood, Ph.D.; Shah Ebrahim, M.D.; John Gallacher Ph.D.; and John Yarnell, M.D.
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