When asked about their secret to aging, the world's oldest people often bring up not sweating the small stuff. In fact, optimism is associated with greater personal happiness, but could it impart biological benefits as well? Researchers at the Harvard School of Public Health suggest it's possible in a new study in the American Journal of Epidemiology. They analyzed data from more than 70,000 women between 2004 and 2012. Optimistic women, they found, are considerably less likely to die from a handful of diseases than their pessimistic counterparts, possibly in part because of reduced inflammation. "Our new findings suggest that we should make efforts to boost optimism, which has been shown to be associated with healthier behaviors," one researcher says.
The study is not without flaws. For one, optimism may be calculated differently from one person to the next. And "reverse causation" could be at play, where people in better health are more likely to be optimistic, reports Live Science. But it's a large study, and the numbers are statistically significant. The most optimistic women were 52% less likely to die from an infection than the least optimistic, and roughly 38% less likely to die from stroke, heart disease, and respiratory disease. The effect was even seen in cancer, though with just a 16% reduction. The lead author tells the New York Times that studies in twins suggest optimism is 25% heritable, so it's 75% "under our own control," while an outside researcher warns NPR we should be careful not to blame patients. (Can one be overly positive?)