The research, reported in Circulation: Journal of the American Heart Association, has found that women who think positive have a lower risk of developing heart disease or dying from any cause compared to pessimistic women.
Researchers also reported that women with a high degree of cynical hostility - harboring hostile thoughts toward others or having a general mistrust of people - were at higher risk of dying; however, their risk of developing heart disease was not altered.
"As a physician, I'd like to see people try to reduce their negativity in general," said Hilary A. Tindle, M.D., M.P.H., lead author of the study and assistant professor of medicine at the University of Pittsburgh.
"The majority of evidence suggests that sustained, high degrees of negativity are hazardous to health," the expert added.
In the largest study to date to prospectively study the health effects of optimism and cynical hostility in post-menopausal women, researchers found that optimistic women, compared to pessimistic women, had a 9 percent lower risk of developing heart disease and a 14 percent lower risk of dying from any cause after more than eight years of follow-up.
Furthermore, women with a high degree of cynical hostility, compared to those with a low degree, were 16 percent more likely to die during eight years of follow-up.
"Prior to our work, the strongest evidence linking optimism and all-cause mortality was from a Dutch cohort, showing a more pronounced association in men," Tindle said.
Tindle's team studied 97,253 postmenopausal women (89,259 white, 7,994 black) ages 50 to 79 from the Women's Health Initiative. The women were free of cancer and cardiovascular disease (CVD) at the start of the study.
Using the Life Orientation Test Revised Questionnaire to measure optimism and cynical hostility, researchers categorized scores into quartiles: high scores of 26 or more were considered optimists; scores of 24-25 were considered mid-high; scores of 22-23 were considered mid-low; and scores below 22 were considered pessimists.
Optimism was defined as answering "yes" to questions like, "In unclear times, I usually expect the best." Pessimism was defined as answering "yes" to questions like, "If something can go wrong for me, it will."