Look for the silver lining . . .

That’s the title of a popular song written by Buddy DeSylva to music by Jerome Kern. The lovely tune, sung by Judy Garland (among others), calls for a positive outlook on life, even in the face of adversity. Indeed, a cheerful disposition can help you get through the tough patches that cloud every man’s life. But does seeing the glass as half full rather than half empty mean you’ll enjoy better health?

According to a series of studies from the United States and Europe, the answer is yes. Optimism helps people cope with disease and recover from surgery. And a positive outlook has an impressive impact on overall health and longevity. Research tells us that an optimistic outlook early in life can predict better health and a lower rate of death during follow-up periods of 15 to 40 years. Here’s a closer look at the evidence.

Optimism and Cardiovascular Disease

A 2014 study from Harvard University and the University of Michigan found that optimism appears to reduce the risk of heart failure. Earlier research linked optimism with protection against stroke and narrowing of the carotid artery, which carries blood to the brain. And scientists have also reported that optimists tend to fare better after heart procedures, such as angioplasty and bypass surgery.

A sunny outlook may help people recover after a heart procedure, but can it also reduce the risk of developing heart and blood vessel disease in the first place? Studies from Finland and the United States suggest it can cut the risk of high blood pressure (hypertension), a major risk factor for heart attack and stroke.

Reducing risk is good, but proven protection is even better. To find out whether optimism actually helps ward off heart disease, scientists from Harvard and Boston University evaluated 1,306 men with an average age of 61. Each volunteer was evaluated for optimism or pessimism along with these risk factors:

None of the men had been diagnosed with coronary artery disease when the study began. Over the next 10 years, the most pessimistic men were more than twice as likely to develop heart disease as the most optimistic men, even after taking other risk factors into account.

Optimism and Overall Health

Optimism appears to protect the heart and circulation. And it’s heartening to learn that it can have similar benefits for overall health.

A large, short-term study evaluated the link between optimism and overall health in 2,300 older adults. Over two years, people who had a positive outlook were much more likely to stay healthy and enjoy independent living than their less cheerful peers.

Staying well for two years is one thing, remaining healthy for the long haul is a different story. In another study, 447 patients were evaluated for optimism as part of a comprehensive medical evaluation between 1962 and 1965. The benefits of a positive outlook were impressive, indeed. Over a 30-year period, optimism was linked to better physical and mental health.

Optimism and Longevity

It’s obvious that healthy people live longer than sick people. If optimism actually improves health, it should also boost longevity. According to two studies from the United States and two from the Netherlands, it does.

Beginning in the early 1960’s, the first American study gave 839 patients a psychological test for optimism–pessimism. They also got a complete medical evaluation. When the patients were rechecked 30 years later, optimism was linked to longevity: For every 10-point increase in pessimism on the optimism–pessimism test, the death rate rose 19%.

A newer study looked at 6,959 students who took a comprehensive personality test when they entered the University of North Carolina in the mid 1960s. During the next 40 years, 476 of the people died from a variety of causes. Cancer was the most common. All in all, pessimism took a big toll; the most pessimistic individuals had a 42% higher rate of death than the most optimistic.

The two Dutch studies reported similar results. In one, researchers tracked 545 men who were free of heart and blood vessel disease and cancer when they were tested for optimism in 1985. Over the next 15 years, the optimists were 55% less likely to die from heart and blood vessel disease than the pessimists, even after the researchers took traditional risk factors and depression into account.

The other study from Holland evaluated 941 men and women between the ages of 65 and 85. People who were optimistic at the start of the study had a 45% lower risk of death during nine years of follow up.

How Does it Work?

Taken together, these studies argue persuasively that optimism is good for your health. But what puts the silver in the silver lining? Here are three possible explanations.

Look for the Doughnut Rather Than the Hole

More study is needed to clarify the link between optimism and good health. It’s likely that multiple mechanisms are involved.

Doctors don’t know if optimism is hard-wired into a person or if a sunny disposition can be nurtured in some way. It’s doubtful that poet McLandburgh Wilson was pondering such weighty questions when she explained optimism in 1915:

            “Twixt the optimist and pessimist
The difference is droll
The optimist sees the doughnut
But the pessimist sees the hole.”

Today’s doctors don’t think much of doughnuts. But they are gathering evidence that optimism is good for health. As you await the results of new research, do your best to seek silver linings, if not doughnuts.

Harvey B. Simon, M.D., is an associate professor of medicine at Harvard Medical School and a member of the Health Sciences Technology Faculty at Massachusetts Institute of Technology. He is the founding editor of the Harvard Men’s Health Watch newsletter and author of six consumer health books, including The Harvard Medical School Guide to Men’s Health (Simon and Schuster, 2002) and The No Sweat Exercise Plan, Lose Weight, Get Healthy and Live Longer (McGraw-Hill, 2006). Dr. Simon practices at the Massachusetts General Hospital; he received the London Prize for Excellence in Teaching from Harvard and MIT.