Interaction between two specific genes might explain why depression and heart disease are associated.
Previous research has suggested that people with depression are more likely to develop heart disease. And, conversely, having had a heart attack, those who are depressed have a worse outcome.

Is there, perhaps, an underlying link? Researchers in Germany studied a group of people with severe depression. They found that they had a mutation in a gene affecting brain function and also one in another gene, which is known to be linked to heart disease. The rate of this double mutation was 17 per cent in the group with depression, compared to only three per cent in a group of healthy controls.

It's not yet known whether this group will go on to develop heart disease or whether they are at increased risk of heart attack. But this study does suggest that genetics could explain at least part of the link between depression and heart disease.