Study Helps Illuminate Link Between Depression, Heart Disease

Depression appears to lead to inflammation, not vice versa, in individuals with coronary heart disease. This is the key finding from large prospective study headed by Mary Whooley, M.D., of the University of California, San Francisco, and reported in the April Psychoneuroendocrinology. The study included 667 subjects evaluated for depression for five consecutive years and for white blood cell count (which indicates systemic inflammation) at baseline and after the five years of follow-up. The researchers found that 66% of the subjects had no depressive symptoms, 13% had depressive symptoms at one annual assessment, and 21% had depressive symptoms at two or more annual assessments. At the end of five years, subjects with recurrent depressive symptoms had significantly higher white blood cell counts than the other two groups did, even after controlling for demographics, cardiac disease severity, health behaviors, and other variables. Baseline white cell count, in contrast, was not significantly associated with subsequent depressive symptoms.

Thus it appears that "depression is a risk factor for inflammation" and that such inflammation in turn might be "a potential mediator in the relationship between depression and adverse cardiac outcomes," Whooley and her colleagues concluded.

And if this is the case, then it might help explain why people who are depressed after having a heart attack are at three to five times the risk of dying than are those who are not depressed after a heart attack. For more on this topic, see Psychiatric News here and here. More information about the interface between depression and heart disease and how depression might lead to negative heart disease outcomes can be found in American Psychiatric Publishing's Text of Psychosomatic Medicine: Psychiatric Care of the Medically Ill, Second Edition.

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