With an estimate of more than six million men in the United States suffering from a depressive disorder, a new study is suggesting that depression may increase the risk of heart failure.

The study, which was presented at the European Society of Cardiology meeting in Stavanger, Norway Friday, found that moderate to severe depression could increase one's risk of heart failure by 40 percent. Depression is a well-known disorder that can prevent people from appreciating and enjoying the things around them.

"We found a dose response relationship between depressive symptoms and the risk of developing heart failure. That means that the more depressed you feel, the more you are at risk," Lise Tuset Gustad, first author of the study and an intensive care nurse at Levanger Hospital in Norway, said in a European Society of Cardiology news release.

In the study, researchers followed nearly 63,000 individuals from Norway. The researchers gathered information about the participants including smoking habits, body mass index, physical activity and blood pressure. Researchers also analyzed and ranked the depression level of each participant using the Hospital Anxiety and Depression Scale.

During the 11 year study researchers found about 1,500 people who had developed heart failure. Gustad said the symptoms of depression can increase the chances of developing heart failure; the risk is greater with the more severe symptoms. Mild symptoms had a five percent chance of developing heart failure, while those with moderate to severe depression symptoms had a 40 percent increased risk.

"Depressive symptoms increase the chance of developing heart failure and the more severe the symptoms are, the greater the risk," Gustad said in a statement. "Depressed people have less healthy lifestyles, so our analysis adjusted for factors such as obesity and smoking that could cause both depression and heart failure. This means we can be confident that these factors did not cause the association."

Gustad believes that depression triggers stress hormones, which increases the pulse and speeds up a person's breathing. It also results with inflammation that may accelerate heart diseases.

"Depression triggers stress hormones. If you're stressed you feel your pulse going up and your breath speeding up, which is the result of hormones being released. Those stress hormones also induce inflammation and atherosclerosis, which may accelerate heart diseases. Another mechanism could also be because depressed people find it more difficult to follow advice about how to take medications and improve their lifestyle," Gustad said.

The National Institute of Mental Health in Washington said signs and symptoms of depression include: "persistent sad, anxious, feelings of hopelessness, guilt, worthlessness, or helplessness." It also includes loss of interest in activities or hobbies once pleasurable, including sex and fatigue and decreased energy.

"People who have lost interest in things they used to enjoy, such as reading or watching a television series, may have the early signs of depression. It's a good idea to see your doctor in these early stages for some advice on how to reduce your depression levels," she said.