PARIS — People with a sunny outlook on life are less likely to develop heart disease than those who are less happy or outright glum, according to a study published on Thursday.
Its authors say it is the first investigation to give objective data to support the belief that high morale also helps a strong heart.
Publishing in the European Heart Journal, the Canadian team followed 1,739 men and women over 10 years who were enrolled in a health-monitoring project in Nova Scotia.
At the start of the study, trained nurses gave an assessment of the participants' risk of heart and disease.
Using both self-reporting and clinical assessment, the observers rated symptoms of depression, hostility and anxiety as well as "positive" counterparts -- joy, happiness, enthusiasm and contentment -- on a five-point scale.
Taking age, sex and cardiovascular risk factors into account, the researchers found that over the 10 years, "increased positive affect" lessened the risk of heart disease by 22 percent for each point on the scale.
"Participants with no positive affect were at a 22-percent higher risk of ischaemic heart disease (heart attack or angina) than those with a little positive affect, who were themselves at 22 percent higher risk than those with moderate positive affect," explained Karina Davidson, director of the Center for Behavioral Cardiovascular Health, New York.
She added: "We also found that if someone who was usually positive had some depressive symptoms at the time of the survey, this did not affect their overall lower risk of heart disease."
The investigators offer up several theories to explain the phenomenon.
One is that people with "positive affect" may have longer periods of rest and relaxation and recover more quickly from stress.
They caution, though, that clinical trials are needed to explore the heart-happiness link before doctors can issue any recommendations on how to prevent cardiac disease by enhancing positive emotions.