Young men with anxiety disorders may have an increased likelihood of developing heart disease by middle-age, a new study suggests.

The study, which followed nearly 50,000 Swedish men for 37 years, found that those who were diagnosed with an anxiety disorder between the ages of 18 and 20 were more likely to develop heart disease by the end of the study.

Of young men with an anxiety disorder, just under 9 percent were eventually hospitalized for or died of heart disease. That compared with just under 4 percent of those who were free of anxiety disorders in early adulthood.

The relationship between anxiety and heart disease was not explained by the range of other factors the researchers were able to take into account - including blood pressure, weight and exercise habits when the study participants were young, as well as their family history of heart disease.

Anxiety disorders themselves were still linked to a doubling in the risk of future heart disease.

The findings, reported in the Journal of the American College of Cardiology, add to evidence tying anxiety disorders to an increased risk of heart disease. It is still unclear whether anxiety itself is to blame; there may be underlying factors that raise the risks of both anxiety disorders and heart problems.

But whether anxiety is the cause or not, these and other recent findings suggest that people with the disorders should be particularly mindful about preventing or controlling major heart disease risk factors, according to Dr. Joel E. Dimsdale of the University of California, San Diego.

“One implication of these studies is that patients with anxiety disorders need to take special care in avoiding risk-enhancing behaviors like smoking, and instead should be looking into risk reduction through activities like aerobic exercise,” Dimsdale, who wrote an editorial published with the study, told Reuters Health in an email.

Other preventable or treatable risk factors for heart disease include high blood pressure, type 2 diabetes and High cholesterol.

For the study, Dr. Imre Janszky and colleagues at the Karolinska Institute in Stockholm analyzed data from 49,321 men who underwent health evaluations for military service in 1969 and 1970.

At that time, 646 men were diagnosed with depression, while 162 were diagnosed with an anxiety disorder. Over the next 37 years, 1,894 men were hospitalized for or died of coronary heart disease, where plaque build-up in the coronary arteries impede blood flow to the heart.

Men who’d had an anxiety disorder in early adulthood showed an increased risk of heart disease, but the same was not true of those with depression. The finding is somewhat surprising, since a number of studies have linked depression to both a heightened risk of heart disease and a poorer prognosis in people with established heart disease.

A study published last month, for example, found that among nearly 97,000 U.S. veterans, those with either major depression or an anxiety disorder - such as generalized anxiety or post-traumatic stress disorder - had a higher risk of suffering a heart attack over seven years than their counterparts without the mental health conditions.

It is not clear why early-onset anxiety, but not depression, was linked to the long-term risk of developing heart disease in this study.

In general, experts suspect that depression and anxiety may affect heart disease risk through direct physiological effects, indirect ways, or both.

The disorders may, for example, have effects on the immune system or the sympathetic and parasympathetic nervous systems, which help regulate the heart’s response to everyday stresses.

Poor mental health may also hinder people’s ability to maintain a healthy lifestyle or to stick with treatments for heart risk factors like high blood pressure. One of the limitations of the current study is that it had information on the men’s lifestyle and overall health only in early adulthood; it is not clear to what extent lifestyle and health problems in middle-age might have accounted for the anxiety-heart link.

“That emotional factors affect the heart is obvious,” Dimsdale writes in his editorial. “How they do so and how to mitigate these effects remains to be discovered.”

As it stands, medical groups such as the American Heart Association do not consider anxiety or depression independent risk factors for heart disease. And studies have not yet shown whether treating anxiety or depression may lower the risk of developing heart disease, or improve the prognosis of people who already have it.

SOURCE:  Journal of the American College of Cardiology, June 29, 2010.