By Lisa Rapaport

(Reuters Health) - Women who have a sunny outlook on life may live longer than their peers who take a dimmer view of the world, a recent study suggests.

Researchers analyzed data collected over eight years on about 70,000 women and found that the most optimistic people were significantly less likely to die from cancer, heart disease, stroke, respiratory disease or infections during the study period than the least optimistic.

“Optimistic people tend to act in healthier ways (i.e., more exercise, healthier diets, higher quality sleep, etc.), which reduces one's risk of death,” said one of the study’s lead authors, Kaitlin Hagan, a public health researcher at Brigham and Women’s Hospital and Harvard University in Boston.

“Optimism may also have a direct impact on our biological functioning,” Hagan added by email. “Other studies have shown that higher optimism is linked with lower inflammation, healthier lipid levels and higher antioxidants.”

Hagan and colleagues examined data from the Nurses Health Study, which began following female registered nurses in 1976 when they were 30 to 55 years old. The study surveyed women about their physical and mental health as well as their habits related to things like diet, exercise, smoking and drinking.

Starting in 2004, the survey added a question about optimism. Beginning that year, and continuing through 2012, researchers looked at what participants said about optimism to see how this related to their other responses and their survival odds.

Researchers divided women into four groups, from least to most optimistic.

Compared with the least optimistic women, those in the most optimistic group were 29 percent less likely to die of all causes during the study period, researchers report in the American Journal of Epidemiology.

Once researchers adjusted the data for health habits, greater optimism was still associated with lower odds of dying during the study, though the effect wasn’t as pronounced.

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Still, the most optimistic women had 16 percent lower odds of dying from cancer during the study, 38 percent lower odds of death from heart disease or respiratory disease, 39 percent lower odds of dying from stroke and a 52 percent lower risk of death from an infection.

While other studies have linked optimism with reduced risk of early death from cardiovascular problems, this was the first to find a link between optimism and reduced risk from other major causes, the study authors note.

One limitation of the study is the possibility that in some cases, underlying health problems caused a lack of optimism, rather than a grim outlook on life making people sick, the authors point out.

They also didn’t include men, though previous research has found the connection between optimism and health is similar for both sexes, said the study’s other lead author, Dr. Eric Kim, also of Brigham and Women’s and Harvard.

Despite the lack of men in the study, the findings still suggest that it may be worthwhile to pursue public health efforts focused on optimism for all patients, Kim said by email.

That’s because even though some people may have a less positive outlook on life for reasons beyond their control like unemployment or a debilitating illness, some previous research suggests that optimism can be learned.

“Negative thinking isn't the cause or the only contributor to these illnesses,” said Dr. Susan Albers, a psychologist at the Cleveland Clinic in Ohio who wasn’t involved in the study. “Mindset is just one factor, but the results of the study indicate they are a significant one and can't be ignored.”

Some people can develop optimism when it doesn’t come naturally, Albers added by email.

“It is worth tweaking your mindset as much as taking your medicine,” Albers said. “Work with a counselor, join with a friend, hang up optimistic messages, watch films and movies with a hopeful, positive message, find the silver lining in the situation.”

SOURCE: http://bit.ly/2heWxf6 American Journal of Epidemiology, online December 7, 2016.