Optimistic women live longer and healthier lives than their pessimistic peers, a new study suggests.

Specifically, researchers found that women who see the glass as half full are at a lower risk for developing heart disease, and have a lower risk of dying from any cause, than those who see the glass as half empty.

The new research, detailed in the journal Circulation, also found that women with a high degree of cynical hostility — defined as harboring hostile thoughts toward others or having a general mistrust of people — were at a higher risk of dying in general.

"As a physician, I'd like to see people try to reduce their negativity in general," said Dr. Hilary A. Tindle, 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 study is the largest to date to examine the health effects of optimism and cynical hostility in postmenopausal women over time. 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.

Separating optimists from pessimists

The researchers used a test called the Life Orientation Test Revised Questionnaire to measure optimism and cynical hostility. Scores were ranked, with high scores of 26 or more considered optimistic and scores below 22 considered pessimistic.

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."

The results showed 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 the eight years of follow-up.

A previous study conducted in the Netherlands also found that optimists had a lower risk of death.

What makes an optimist

The new study found links between particular characteristics and optimism. Other studies have also found that certain factors are likely to make people more optimistic, particularly age — a 2006 study found that optimism tended to increase as people got older. A 2009 study suggests that humans are optimistic by nature.

In the new study, race seemed to affect the relationship between optimism and death, with a stronger association seen in African-American women as compared to white women.

Researchers also found that optimists (as compared to pessimists) were more likely to be younger (especially in blacks); live in the Western United States; report higher education and income; be employed and have health insurance; and attend religious services at least once a week.

Optimists were less likely to have diabetes, high blood pressure, high cholesterol or depressive symptoms, smoke, be sedentary or have a high body mass index. However, the relationship between optimism and heart disease and death persisted even after considering all of these factors.

"This study is a very reasonable stepping stone to future research in this area, both on potential mechanisms of how attitudes may affect health, and for randomized controlled trials to examine if attitudes can be changed to improve health," Tindle said.