Depressed people are more likely to have a heart attack than smokers or those with high cholesterol, according to one of the largest and longest studies on the link between depression and heart disease.
People with depression run about twice the risk of a heart attack as the general population, researchers said Monday at a meeting of the American Heart Association in Orlando.
Smoking and high cholesterol are two of the strongest known risk factors for heart disease. But this is the first time depression has been directly linked to first heart attacks, said researchers from New York’s Albert Einstein College of Medicine.
“The question is, why is this happening, and that’s going to need a lot more study,” said Hillel Cohen, who conducted the research. Previous studies have shown depression can hinder recovery among cardiac patients.
Cohen’s study followed 6,327 depressed people for an average of five years. To qualify for the study, subjects had to have depression serious enough to seek medical treatment. The study did not look into whether treating the depression would remove the additional risk.
Researchers speculated depression releases a hormone that somehow contributes to heart disease. Another explanation could be an unknown biological factor could be responsible for both depression and heart disease.
“Depression is a state of arousal - the fight-or-flight response is active in depressed people,” said Chris Strychacz of the University of Missouri, Kansas City. Strychacz presented another study on heart disease and depression at the conference Monday.
Cohen said he does not believe people are becoming depressed over the knowledge they have heart disease. In fact, the link between depression and a heart attack was even stronger among people who were unaware they had heart disease.
Cohen found depressed people with no knowledge of their heart disease were 2.3 times more likely than the average person to have a heart attack. For all depressed people in the study, the risk was 1.8 times greater than that of the general public. Smokers are 1.5 times more likely to have heart attacks and people with high cholesterol are 1.4 times more likely, Cohen said.
The study found the link between depression and heart disease was slightly higher for men.
Another study presented Monday showed people who are severely depressed after a heart attack - about one in four patients - are more likely to die in the following months than people who are not depressed.