More evidence that the mind affects the body has come from a new study of patients who had coronary bypass surgery.

Researchers have discovered that patients are more likely to die after surgery if they are depressed, and the risk increases with the depth of the depression. Depression is a fairly common reaction following bypass surgery, with up to 47 per cent of all patients suffering from it to some extent. It's something that heart surgeons have noticed, but the link had never been proven because research had been on groups that were too small to be a scientifically valid sample. So researchers from Duke University in North Carolina followed up for five years 817 patients who had bypass surgery at the university's medical centre.

During that time, 38 per cent of the group suffered depression, 26 per cent of whom had mild depression, and the remainder had severe attacks. Of the 122 patients who died during the five years of follow-up, researchers found that those who suffered deep depression were nearly two-and-a-half times more likely to die, while the risk dropped slightly - to just over two times - among patients with mild depression.

Despite all the advances of modern surgery, a positive outlook has as much to do with survival as anything else, researchers concluded.

(Source: The Lancet, 2003; 362: 604-9).