Laughter, along with an active sense of humor, may help protect against heart attacks, according to a study by cardiologists at the University of Maryland Medical Center (UMMC) in Baltimore.

The study, which is the first to indicate that laughter may help prevent heart disease, was presented at the American Heart Association's 73rd Scientific Sessions on November 15 in New Orleans. The researchers found that people with heart disease were 40% less likely to laugh in a variety of situations compared to people of the same age without heart disease.

"The old saying that 'laughter is the best medicine,' definitely appears to be true when it comes to protecting your heart," said Michael Miller, M.D., F.A.C.C., director of the UMMC Center for Preventive Cardiology. "We don't know yet why laughing protects the heart, but we know that mental stress is associated with impairment of the endothelium, the protective barrier lining our blood vessels. This can cause a series of inflammatory reactions that lead to fat and cholesterol build-up in the coronary arteries and ultimately to a heart attack," stated Dr. Miller who is also an associate professor of medicine at the University of Maryland School of Medicine.

In the study, researchers compared the humor responses of 300 people. Half of the participants had either suffered a heart attack or had undergone coronary artery bypass surgery. The other 150 were healthy, age-matched participants who did not have heart disease.

Participants in the study were asked to complete two questionnaires. One questionnaire had a series of multiple-choice answers to find out how much or how little the participant laughs in certain situations. The second questionnaire used 50 true or false answers to measure anger and hostility. For example, the questions included the following:

From the multiple-choice section:

If you arrived at a party and found that someone else was wearing a piece of clothing identical to yours, would you

(a) not find it particularly amusing

(b) be amused but not show it outwardly

(c) smile

(d) laugh or

(e) laugh heartily.

If you were eating in a restaurant with some friends and the waiter accidentally spilled a drink on you, would you

(a) not find it particularly amusing

(b) be amused but not show it outwardly

(c) smile

(d) laugh or

(e) laugh heartily.

From the true or false section:

People with heart disease were less likely to recognize humor or use it to get out of uncomfortable situations. They generally laughed less, even in positive situations and they displayed more anger and hostility.

"The ability to laugh -- either naturally or as learned behavior -- may have important implications in societies such as the U.S. where heart disease remains the number one killer," Miller stated. "We know that exercising, not smoking and eating foods low in saturated fat will reduce the risk of heart disease. Perhaps regular, hearty laughter should be added to the list."

Miller said it may be possible to incorporate laugher into our daily activities, just as we do with other heart-healthy activities, such as taking the stairs instead of the elevator.

"We could perhaps read something humorous or watch a funny video and try to find ways to take ourselves less seriously," Miller said "The recommendation for a healthy heart may one day be exercise, eat right and laugh a few times a day."