Depression is both a risk factor for developing heart disease and makes things worse for those who already have it. Researchers from the University Medical Centre in Groningen, in the Netherlands have been looking into this issue in more detail. They studied 1,019 people with an average age of 67 who had stable coronary heart disease asking them about their depression symptoms. They found that those who had somatic (bodily) symptoms of depression were more likely to have health problems with fatigue, appetite problems and sleeplessness increasing the risk most. However, the cognitive symptoms of depression, such as difficulty in concentrating, were not found to increase people's risk.
You can find out more about this research by clicking on the link in the title of this post.