Happy People Have Better Heart Health

According to Karina Davidson, PhD, of Columbia University Medical Center, New York, higher levels of positive affect, a measure of happiness, were associated with a significantly lower risk of having a cardiovascular event over a 10-year period (P=0.02).

The association remained significant even after accounting for negative emotions, including depression, anxiety, and hostility.

The findings suggest that strategies to prevent heart disease may be bolstered by increasing an individual's zest for life, they said, noting, however, that this observational data cannot be used to make practice recommendations.

"Whether increasing positive affect would decrease the risk for coronary heart disease is an exciting, but as of yet untested hypothesis, remaining to be addressed."

In an accompanying editorial, Bertram Pitt, MD, and Patricia Deldin, PhD, of the University of Michigan in Ann Arbor, said randomized trials in patients with heart disease are under way to evaluate interventions for increasing positive affect as a way to counter the effects of depression.

One such approach, called behavioral activation, involves patients listing hobbies and activities that make them happy and then trying to increase how frequently they participate in them.

"These new treatments could open up an exciting potential new approach for treating patients with known cardiovascular disease who develop depression," the editorialists wrote.

Positive affect -- defined as the experience of pleasurable emotions such as joy, happiness, excitement, enthusiasm, and contentment -- has been shown in previous studies to be associated with increased survival, improved immune function, and lower risks of diabetes and hypertension. Negative emotions, including depression, have been linked to a greater risk of heart disease.

According to Davidson and her colleagues, positive affect is thought to be predictive of cardiovascular health independent of negative emotions.

In the current analysis, 1,739 adults with no history of heart disease at baseline were followed for up to 10 years. Positive affect was assessed at baseline by trained nurses who asked about each participant's responses to various situations. Both the answers and the participants' demeanor were used to rate positive emotions on a five-point scale.

In general, those with higher scores had better overall health. They were less likely to be current smokers and had lower total cholesterol levels, blood pressure, and levels of hostility and anxiety (P≤0.03 for all). Through follow-up, there were 145 acute ischemic heart disease events, including nine deaths.

After adjustment for age, sex, cardiovascular risk factors, symptoms of depression and anxiety, and hostility, each one-point increase in positive affect score was associated with a 22% lower risk of having a cardiovascular event.

Depressive symptoms were independently associated with a slightly higher risk of having an acute event, but hostility and anxiety were not. Although a causal relationship between positive affect and heart disease could not be proven, Davidson and her colleagues noted that positive affect has been shown in previous studies to predict enhanced parasympathetic modulation of heart rate.

It has also been associated with lower blood pressure, norepinephrine reactivity, and cortisol levels.

Positive affect may also protect against heart disease by improving sleep habits and the ability to quit smoking, they said. "However," they wrote, "further research is needed."

Practice Pearl: Explain to interested patients that this study could not establish a causal relationship between happiness and the risk of coronary heart disease.

Davidson K, et al "Don't worry, be happy: positive affect and reduced 10-year incident coronary heart disease: the Canadian Nova Scotia Health Survey" Eur Heart J 2010; DOI: 10.1093/eurheartj/ehp603.