What the Study Showed
The risk of stroke is increased in people who suffer from depression, according to this two-decade study carried out by the Centers for Disease Control and published in the journal Psychosomatic Medicine.

How it was Done
Researchers analyzed data from 6,095 individuals as part of the first National Health and Nutrition Examination Survey (NHANES I). At the start of the study, all the participants were stroke-free and between the ages of 25 and 74. They were given physical examinations and queried about their level of physical activity, diet, medical history, and such lifestyle habits as smoking.

They also filled out a series of psychological questionnaires designed to evaluate the prevalence of such feelings as sadness, hopelessness, and other mood states. Follow-up health and psychological examinations were done four times from 1982 to 1992.

Why It’s Important
Several physical risk factors for stroke have been firmly established over the years, including heart disease, serum cholesterol status, high blood pressure, and diabetes. This study sheds new light on the importance of emotional risk factors as well-namely, that depression can have unexpected consequences so it’s important to treat this psychological condition aggressively.

The findings were notable: People who had high levels of depressive symptoms were significantly more likely to suffer a stroke; in fact, they had a 73% increased risk. Moderate levels of depression increased the risk by 25%. Interestingly, high levels of cheerfulness were not protective.

Exactly how depression affects a person’s stroke risk remains somewhat of a mystery. Depressed states, however, are known to boost the arousal of the autonomic nervous system, which is associated with the “fight or flight” reflex response in all of us.

It’s possible that in some people the nervous system fails to revert to resting levels after a stressful situation is resolved. This exposes the body to on-going stress hormones (such as epinephrine) that increase the risk of stroke because their continued presence leads to a narrowing of blood vessels that feed the brain and heart.

Other studies have shown that depression boosts the activity of the sympathetic nervous system, possibly altering the functioning of the immune system and indirectly increasing the risk of blood clots. Another scenario is that depression can exacerbate illnesses linked to an elevated risk for stroke, such as high blood pressure.

Additional Findings
People with high levels of depression were at varying risk for stroke depending on their race and gender. For white men, depression increased the stroke risk by 68%, while for white women the increased risk was 52%. However, for African Americans of both genders, depression increased the risk for stroke by 160%.

Source: Jonas BS, Mussolino ME. Symptoms of depression as a prospective risk factor for stroke. Psychosom Med 2000;62:463-471