Dr. Erik J. Giltay, of the Psychiatric Center GGZ Delfland, in Delft, the Netherlands analyzed data from about 1,000 patients of the Arnhem Elderly Study and questioned them on their health, self-respect, morale, optimism and relationships.

Participants reporting high levels of optimism had a 55 percent lower risk of death from all causes and a 23 percent lower risk of cardiovascular death.

"We found that the trait of optimism was an important long-term determinant of all-cause and cardiovascular mortality in elderly subjects independent of sociodemographic characteristics and cardiovascular risk factors," the authors wrote in the Archives of General Psychiatry.

"A predisposition toward optimism seemed to provide a survival benefit in elderly subjects with relatively short life expectancies otherwise."