Groundbreaking research finds suffering from depression can cause heart disease.

Digestive disorders, chronic pain, stroke, early death – they’re all physical conditions linked to depression.

Now, cardiovascular disease can be added to that list.

New research out of Germany, and published in the journal Atherosclerosis, found depression is equal with high cholesterol levels, smoking, and obesity as a risk factor for heart disease.

That’s right. Mental illness is just as dangerous as obesity in the way it can lead to clogged arteries and a fatal heart attack.

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The reason for this is not yet confirmed. Some researchers believe it’s about the affect of the stress hormone cortisol. Others think depression’s tendency to cause unhealthy behaviours, such as smoking and drinking and eating junk food, might be the reason for the link.

Whatever the mechanisms involved, the findings are concerning and also enlightening – they show the need for a crossover between mental and physical health care: Patients with depression should also undergo regular heart health checks.

The study followed 3,500 German men between the ages of 45 and 74 over a period of 10 years. The researchers looked at data on the participants’ physical and mental health. They compared depression with other risk-factors for heart disease such as high cholesterol and obesity.

The results?

The researchers found that men with depression were at equal risk of suffering fatal heart disease as men with high cholesterol levels or obesity.

They attributed 15 per cent of cardiovascular-related deaths to depression.

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Interestingly, the link was found to go both ways. Patients with cardiovascular disease are at risk of developing depression. And people with depression are at risk of suffering heart disease.

“An association between psychological health and disease has been appreciated for centuries,” Ahmed Tawakol, a professor of medicine at Harvard Medical School and who has worked in stress and mental health, told The Huffington Post.

“However, only over the past decades has mounting evidence suggested that stress and depression may be more than simple markers of heart disease; they might be important causes.”