THURSDAY, March 25 (HealthDay News) -- An optimistic outlook might strenghten your body's ability to fight off infection, new research suggests.
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The finding doesn't prove that looking on the sunny side leads to better health, but it does add to evidence of a link between attitude and disease by suggesting that "a single person -- with the same personality and genes -- has different immune function when he or she feels more or less optimistic," said study author Suzanne C. Segerstrom, a professor in the department of psychology at the University of Kentucky.
From 2001 to 2005, Segerstrom and a colleague gave surveys to 124 first-year law students. The students, the majority of whom were white (90%) and female (55%), answered questions about topics such as their levels of optimism about their success in school.
The participants also were given an injection of an antigen that makes the immune system react by creating a bump on the skin. A bigger bump means that the immune system reaction is stronger.
The researchers, who reported their findings in the March issue of Psychological Science, found that the immune response became more powerful in individual students as they became more optimistic over time, and lessened as they became more pessimistic.
But there's more to it. "When people felt more optimistic, they also felt more happy, attentive and joyous, and that accounted for some of the relationship between optimism and immunity," Segerstrom said.
In the big picture, the findings suggest that the effect of optimism on immunity may be limited, "as it leaves room for lots of other factors that contribute to fluctuations in immunity over time," she said.
James E. Maddux, a professor of psychology at George Mason University, said the findings are "another example of the power of optimism, of what used to be called positive thinking back in the 1950s and 1960s."
He added, "It's hard to make any firm conclusion from a single study, but it's one more piece of evidence that what we think actually matters, in some very important ways."
So what's going on in the body? If there is a link between attitude, emotions and health, how does it work? Dr. Hilary Tindle, a researcher at the University of Pittsburgh's Center for Research on Health Care, has several theories.
One is that "happier or more positive, hopeful people tend to live healthier," she said. And hopeful people may react in healthier ways to stress, helping them to recover more quickly.
Also, "more positive individuals are also more likely to adhere to medical therapy and advice, and therefore may be healthier on that basis," Tindle added.
In a study of women published last August, Tindle found that optimism appears to have an effect on the heart and longevity. "Optimistic women had more stable risk profiles, with less high blood pressure and diabetes. They didn't smoke as much and tended to exercise more. So their lower risk might just be associated with living healthier," she said.
Or, she noted, a woman's outlook on life might affect how she responds to stress. Pessimism and cynical hostility might lead to higher blood pressure, higher heart rate and other physical risk factors, Tindle reported.
Copyright © 2010 HealthDay. All rights reserved.
SOURCES: Suzanne C. Segerstrom, Ph.D., professor, department of psychology, University of Kentucky, Lexington; Hilary Tindle, M.D., M.P.H., researcher, Center for Research on Health Care, division of general internal medicine, University of Pittsburgh; James E. Maddux, Ph.D., professor, department of psychology, George Mason University, Fairfax, Va.; March 2010 Psychological Science