Columbia University Medical Center researchers studying the link between emotions and heart disease believe that their recent study, published in the latest issue of the European Society of Cardiology’s European Heart Journal, is the first to show a relationship between positive emotions and coronary heart disease.
In other words, being happy may be good for your heart, says Karina Davidson, PhD, the Herbert Irving Associate Professor of Medicine & Psychiatry and director of the Center for Behavioral Cardiovascular Health, who led the research. Although it was observational research in a trial population that had suffered cardiac events, the study suggests that it might be possible to help prevent heart disease by enhancing people’s positive emotions.
Over a period of 10 years, Dr Davidson and her colleagues followed 1,739 healthy adults (862 men and 877 women) who participated in the 1995 Nova Scotia Health Survey. At the start of the observational study, trained nurses assessed the participants’ risk of heart disease 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 are usually stable and trait like, particularly in adulthood. After taking into account age, sex, other cardiovascular risk factors and negative emotions, the researchers found that, over the 10 year period, increased positive affect was associated with less risk of heart disease by 22 percent per point, on a five point scale measuring levels of positive affect expression (ranging from "none" to "extreme").
"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," Dr Davidson said. "As far as we know, this is the first prospective study to examine the relationship between clinically assessed positive affect and heart disease."
The researchers speculate about the possible mechanisms by which positive emotions might help confer long term protection from heart disease. These include influence on heart rate variability, sleeping patterns and smoking cessation.
"We have several possible explanations," said Dr Davidson. "First, those with positive affect may have longer periods of rest or relaxation physiologically. Second, those with positive affect may recover more quickly from stressors and may not spend as much time ‘re-living’ them, which in turn seems to cause physiological damage."
"If trials support our findings, then these results will be incredibly important in describing specifically what clinicians and patients could do to improve health," Dr Davidson said. "However, it would be premature to make clinical recommendations without clinical trials to investigate the findings further."
An observational study draws inferences about the possible effect of a treatment on subjects, where the assignment of subjects into a treated group (in this case, the group measured in the Nova Scotia Health Survey) versus a control group is outside the control of the investigator. However, randomised controlled trials of interventions to increase positive affect in patients with cardiovascular disease are now under way and should help determine the effectiveness of increasing positive affect on cardiovascular outcome.
(Source: Columbia University: European Heart Journal: February 2010)