Stay positive: Study shows that optimists live longer

Optimists outlive pessimists, a new study shows. Of nearly 100,000 women enrolled in the Women's Health Initiative, those who gave optimistic answers on a personality test were 9% less likely to develop heart disease within eight years — and 14% less likely to die — than women who got low optimism scores on the test.

TIME's Alice Park wrote about an earlier version of this study in the spring. (See the full story here.) She writes:

Previous studies have indeed documented the life-extending benefits of optimism, although most of that research has involved men and has been conducted in small numbers. What's more, not all studies have done a good job of weeding out potentially confounding factorssuch as health status and lifestyle. That's what makes the new study different. "Taking into account income, education, health behaviors like [controlling] blood pressure and whether or not you are physically active, whether or not you drink or smoke, we still see optimists with a decreased risk of death compared to pessimists," says Dr. Hilary Tindle, lead author of the study. "I was surprised that the relationship was independent of all of these factors."

The study also found an interesting and somewhat disturbing difference in the way that attitude is related to longevity for black women v. white women.

Pessimistic black women in the study were 33% more likely to have died after eight years than optimistic black women, while white pessimists were only 13% more likely to have succumbed than their optimistic counterparts. The numbers in the study weren't large enough to support any definitive explanations for this racial gap, but "there is definitely a suggestion that whites and blacks may be different in how optimism affects longevity," says Tindle.

So does optimism help you live longer or does good health keep you upbeat? As is so often the case, it's tough to tell. But if staying positive can help you to stay happy, too, we might as well give it a try.