Laughter may really be the best medicine

A daily dose of laughter may be good for the heart because, like exercise, it makes blood vessels work more efficiently, say US researchers.

Depression, on the other hand, can raise the risk of dying from heart failure, a separate study found.

The two studies, presented at a meeting of the American College of Cardiology in Orlando, Florida, show how psychological factors can affect a person's health.

"We don't recommend that you laugh and not exercise, but we do recommend that you try to laugh on a regular basis," said Dr Michael Miller of the University of Maryland School of Medicine in Baltimore.

"Thirty minutes of exercise three times a week and 15 minutes of laughter on a daily basis is probably good for the vascular system."

Dr Miller and colleagues at the school showed two movies, one humorous, one stressful, to 20 healthy volunteers and tested the function of their blood vessels.

The researchers specifically looked at the endothelium, the lining of the vessels, and found that blood flow was reduced in 14 of the 20 volunteers after stressful movie clips.

But blood flowed more freely in 19 of the 20 when they laughed at funny movie segments.

Average blood flow increased 22 per cent during laughter, and decreased 35 per cent during mental stress.

"The endothelium is the first line in the development of atherosclerosis or hardening of the arteries, so, given the results of our study, it is conceivable that laughing may be important to maintain a healthy endothelium, and reduce the risk of cardiovascular disease," Dr Miller said.

Laughter may be almost as helpful as exercise, he said.

"The magnitude of change we saw in the endothelium is similar to the benefit we might see with aerobic activity, but without the aches, pains and muscle tension associated with exercise," he said.

In a second study, Dr Wei Jiang and colleagues at Duke University in North Carolina followed 1005 heart failure patients and also tested them for depression.

Those with mild depression had a 44 per cent greater risk of dying, Dr Jiang said. "This adverse association of depression and increased long-term mortality was independent of other factors, including age, marriage, cardiac function and the root cause of the heart failure."

"We believe that our study appears to identify a group of these patients who are at a higher risk for dying."

Dr Jiang said it was not clear why, but patients with depression tended not to exercise or take medications properly.

"Also, depressed patients tend to make unhealthy lifestyle choices in such areas as diet and smoking."

Doctor's orders

30 minutes of exercise three times a week.

15 minutes of laughter every day.

Source: Heart researcher Michael Miller, University of Maryland

- REUTERS