Staying happy and positive can help ward off heart disease, a new study has suggested.
The new research showed that people who are usually happy, enthusiastic and content are less likely to develop heart disease than those who tend not to be happy.
Researchers believe that this study is the first to show such an independent relationship between positive emotions and coronary heart disease.
Study's lead author Dr Karina Davidson said that although this was an observational study, her study did suggest that it might be possible to help prevent heart disease by enhancing people's positive emotions.
However, she warned that it would be premature to make clinical recommendations without clinical trials to investigate the findings further.
"We desperately need rigorous clinical trials in this area. If the trials support our findings, then these results will be incredibly important in describing specifically what clinicians and/or patients could do to improve health," said Dr Davidson, who is the Herbert Irving Associate Professor of Medicine & Psychiatry and Director of the Center for Behavioral Cardiovascular Health at Columbia University Medical Center (New York, USA).
Over a period of ten years, Davidson and her colleagues followed 1,739 healthy adults (862 men and 877 women) who were participating in the 1995 Nova Scotia Health Survey.
At the start of the study, trained nurses assessed the participants' risk of heart disease and, with both self-reporting and clinical assessment, they measured symptoms of depression, hostility, anxiety and the degree of expression of positive emotions, which is known as "positive affect".
Positive affect is defined as the experience of pleasurable emotions such as joy, happiness, excitement, enthusiasm and contentment. These feelings can be transient, but they are usually stable and trait-like, particularly in adulthood.
Positive affect is largely independent of negative affect, so that someone who is generally a happy, contented person can also be occasionally anxious, angry or depressed.
After taking account of age, sex, cardiovascular risk factors and negative emotions, the researchers found that, over the ten-year period, increased positive affect predicted less risk of heart disease by 22% per point on a five-point scale measuring levels of positive affect expression.
"Participants with no positive affect were at a 22% higher risk of ischaemic heart disease (heart attack or angina) than those with a little positive affect, who were themselves at 22% higher risk than those with moderate positive affect," Davidson said.
"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.
"As far as we know, this is the first prospective study to examine the relationship between clinically-assessed positive affect and heart disease," Davidson added.
The study has been published in the Europe's leading cardiology journal, the European Heart Journal.
