March 9, 2009

Depression linked to heart disease

[Posted: Fri 06/03/2009 by Joanne McCarthy]

A history of major depression increases the risk of heart disease over and above any genetic risks, US researchers have said.

According to the findings, men with depression in 1992 were twice as likely to develop heart disease in the ensuing years, compared to men with no history of depression.

The researchers analysed data from more than 1,200 male twins who served in the US military during the Vietnam War. The men were surveyed on a variety of health issues in 1992, including depression, and were assessed again in 2005.

“Based on our findings, we can say that after adjusting for other risk factors, depression remains a significant predictor of heart disease,” said the study’s author, Prof Jeffrey Scherrer of Washington University School of Medicine.

“In this study, we have demonstrated that exposure to depression is contributing to heart disease only in twins who have high genetic risk and who actually develop clinical depression,” he added.

In twins with high genetic risk common to depression and heart disease, but who never develop depression itself, there was no increased risk for heart disease. The findings strongly suggest that depression itself independently contributes to a risk of heart disease, the author said.

The researchers were looking for evidence of ‘incident’ heart disease, an event such as a heart attack, heart surgery, stent placement or medical treatment for angina. Those who had evidence of heart disease prior to the original survey in 1992 were excluded from this study.

Because twins were studied, the researchers could divide participants into risk groups – twins with high genetic and environmental risk for depression, those with moderate risk and those with a low risk. The risk groups then were compared for incident heart disease, adjusting for other influences on heart disease such as smoking, obesity, hypertension (high blood pressure) and diabetes.

Twins automatically are matched by age. They normally grow up in the same family environment, and in the case of identical twins, they share identical DNA.

“If one twin has depression, but his twin brother does not, both twins will share genetic vulnerability for depression, but it turns out the twin who was not depressed has less risk for heart disease,” said Prof Scherrer.

Therefore depression itself remains a significant contributor to incident heart disease after controlling for genes, environment and mental and physical risk factors, he added.

The researchers plan to follow these twins as they age. They also plan to study the effects of successful depression treatment on heart disease risk.

The findings were reported at the annual meeting of the American Psychosomatic Society in Chicago this week.

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