A study of 100,000 women ages 50 and over since 1994, presented at the American Psychosomatic Society's annual meeting Thursday, found a strong correlation between optimism and a person's risk for cancer-related death, heart disease and early death.

The team, led Dr. Hilary Tindle, also looked at women who were highly mistrustful of other people - a group they called "cynically hostile" - and compared them with women who were more trusting. Women in the cynically hostile group tended to agree with questions such as: "I've often had to take orders from someone who didn't know as much as I did" or "It's safest to trust nobody," Tindle said in a telephone interview for Reuters.

Interestingly, the study also revealed that pessimistic black women were 33% more likely to have died than their optimistic peers, while only 13% of white women who were pessimistic were more likely to have died than their 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.

Those who ranked as being the most optimistic were more likely to live 8 years later, while those who ranked among being the most pessimistic were more likely to have died, including from causes such as cancer and heart disease.

Optimistic people have more friends and a larger social network on which they can rely during crises; they also tend to cope better on their own with stress, a risk factor that has been associated with high blood pressure, heart disease and early death in previous studies. It isn't entirely clear how optimists manage stress so well, but it may have something to do with their physiological makeup — genes and metabolic processes that keep them from panicking during troubling times.