Researchers at University of Pittsburgh looked at rates of death and chronic health conditions among participants of the Women's Health Initiative study, which has followed more than 100,000 women ages 50 and over since 1994.

Women who were optimistic – those who expect good rather than bad things to happen – were 14 per cent less likely to die from any cause than pessimists and 30 per cent less likely to die from heart disease after eight years of follow up in the study.

Optimists were also less likely to have high blood pressure, diabetes or smoke cigarettes.

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.

"These questions prove a general mistrust of people," said Tindle, who presented her study Thursday at the American Psychosomatic Society's annual meeting in Chicago.

That kind of thinking takes a toll.

"Cynically hostile women were 16 per cent more likely to die (during the study period) compared to women who were the least cynically hostile," Tindle said.

They were also 23 per cent more likely to die from cancer.

Tindle said the study does not prove negative attitudes cause negative health effects, but she said the findings do appear to be linked in some way.

"I think we really need more research to design therapies that will target people's attitudes to see if they can be modified and if that modification is beneficial to health," she said.