By Alan Mozes
In the review of 15 studies that collectively involved almost 230,000 men and women, the findings were remarkably consistent, the study authors added.
"We found that optimists had a 35% lower risk for the most serious complications due to heart disease, compared to pessimists," said lead author Dr. Alan Rozanski, a professor of cardiology at Mount Sinai St. Luke's Hospital in New York City.
That mind-body connection held up across all age groups, said investigators, ranging from teenagers to those in their 90s. That "suggests that optimism may be an asset, regardless of age," Rozanski noted.
The studies also found the more positive one's outlook, the less one's risk for heart trouble or death.
Ten of the studies specifically looked at positivity's impact on heart health, while nine looked at how a person's outlook affected their risk of dying from a wide range of illnesses.
Many of the investigations asked basic questions touching on expectations of the future. In response, some participants indicated that they generally felt upbeat despite the uncertainty of what's to come. Others said they never assume that things will pan out well down the road.
Over time, those who held more positive viewpoints were more likely to remain heart-healthy.
Yet, despite suggesting that "the magnitude of this association is substantial," Rozanski and his colleagues stressed that the review can't prove that optimism directly protects against heart disease and premature death.
Still, the team pointed to a whole host of potential reasons why positivity -- directly or indirectly -- may help stave off illness.
Some of the studies in the review indicated that optimistic people are more adept at problem-solving, better at developing coping mechanisms, and more apt to realize goals. And those are the kind of skills that could drive someone to take a more active interest in monitoring and maintaining their health, the researchers said.
"Consistent study has shown that optimists have better health habits," Rozanski noted. "They are more likely to have good diets and exercise," and they may be less likely to smoke.
"Increasing data also suggests that optimism may have direct biological benefits, whereas pessimism may be health-damaging," he added. "This biological connection has already been shown for some other psychological risk factors, such as depression."
This is not the first study to find such a link. Research published in the Journal of the American Medical Association in August found an upbeat view of life boosted the odds of living to a ripe old age.
Looking ahead, Rozanski's team pointed to the potential for developing new mind-body treatments, likely in the realm of behavioral therapy, designed to cut down on pessimism and boost optimism.
"However, further research will need to assess whether optimism that is enhanced or induced through directed prevention or intervention strategies has similar health benefits versus optimism that is naturally occurring," the report cautioned.
The findings were published Sept. 27 in the journal JAMA Network Open.
Dr. Jeff Huffman, director of cardiac psychiatry research at Massachusetts General Hospital, cowrote an editorial that accompanied the study.
The review provides "yet more evidence that optimism seems to be an independent predictor of superior cardiac health," he said.
As to why that is, Huffman agreed that optimism is "associated with more physical activity, healthier diet, and a range of other healthy lifestyle behaviors, and it is likely this association that explains a lot of the benefit."
But optimism also impacts biological processes, he added. And ultimately, "the mechanism by which optimism leads to better health is likely a combination of biology and behavior."