People with a tendency to experience positive emotions, such as being happy, enthusiastic and content, are also less likely to to develop heart disease than those who tend not to experience it, suggests a new American study: however the researchers said the findings should be confirmed via clinical trials before making any clinical recommendations.

The study, with an accompanying editorial, is published in the 17 February advance online issue of the European Heart Journal, and was led by Dr Karina Davidson, Herbert Irving Associate Professor of Medicine and Psychiatry and Director of the Center for Behavioral Cardiovascular Health at Columbia University Medical Center, New York, USA.

Having positive emotions, clinically known as “positive affect”, is a state characterised by pleasurable feelings such as joy, enthusiasm, excitement, happiness and contentment. The experience of these feelings can be transient, but they tend to be stable and “trait-like” (part of one’s “personality”), especially once we become adults.

Negative affect is associated with feelings of anxiety, depression and hostility, and is largely independent of positive affect.

“As far as we know, this is the first prospective study to examine the relationship between clinically-assessed positive affect and heart disease,” Davidson told the media.

She noted that although this was an observational study, the findings were strong enough to suggest that enhancing people’s positive emotions may protect them against heart disease, but said we should wait for clinical trial results before reaching this conclusion more firmly.

She said if confirmed by clinical trials, then:

“These results will be incredibly important in describing specifically what clinicians and/or patients could do to improve health.”

For the study, Davidson and colleagues followed 1,739 healthy men (862) and women (877) who were taking part in the 1995 Nova Scotia Health Survey, where via self-reports and clinical measurements, trained nurses had assessed their risk of heart disease at the start of the study. The nurses had also measured symptoms of positive and negative affect.

When they analysed the data, and took into account age, sex, cardiovascular risk factors and negative emotions, the researchers found that over the ten years of the study period, there was a steady trend linking increased positive effect with lower risk of heart disease.

The positive effect scale was based on five points, ranging from “none” to “extreme”. The trend showed a 22 per cent lower risk of heart disease for every point of increase on the five-point positive effect scale, as Davidson explained:

“Participants with no positive affect were at a 22 per cent higher risk of ischaemic heart disease (heart attack or angina) than those with a little positive affect, who were themselves at 22 per cent higher risk than those with moderate positive affect.”

“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,” added Davidson.

The researchers concluded that:

“In this large, population-based study, increased positive affect was protective against 10-year incident CHD [coronary heart disease], suggesting that preventive strategies may be enhanced not only by reducing depressive symptoms but also by increasing positive affect.”

Speculating on ways that positive affect might protect people from heart disease, the authors suggested it could have an effect on heart rate, sleeping patterns and stopping smoking.

People with positive affect may rest and relax more often and for longer, said Davidson, explaining that:

“Baroreflex and parasympathetic regulation may, therefore, be superior in these persons, compared to those with little positive affect.”

(Baroreflex regulation is part of the body’s natural way of keeping blood pressure steady by bringing it down when it gets too high, and parsympathetic regulation is that part of the nervous system that looks after functions like urination and defecation, processes that require slower responses compared to the the sympathetic nervous system that handles more immediate stress-related responses).

Another explanation might be that people with positive affect recover more quickly from stressors and spend less time re-living them, for which evidence suggests this causes physiological damage. However, Davidson warned that these thoughts were purely speculative, as:

“We are just beginning to explore why positive emotions and happiness have positive health benefits.”

However, Davidson pointed out that depression is often successfully treated by increasing positive affect as a well as decreasing negative affect, and if clinical trials confirm these findings, it would be quite easy to assess positive affect in people and recommend ways to increase it and protect them from heart disease.

In the meantime, people interested in these preliminary findings can still take some simple steps to increase their positive affect, she added.

Some people wait for their annual vacation to have fun, which is like deprivation followed by bingeing instead of moderation and consistency, explained Davidson.

“If you enjoy reading novels, but never get around to it, commit to getting 15 minutes or so of [daily] reading in,” she suggested.

“If walking or listening to music improves your mood, get those activities in your schedule. Essentially, spending some few minutes each day truly relaxed and enjoying yourself is certainly good for your mental health, and may improve your physical health as well (although this is, as yet, not confirmed),” she added.

In an accompanying editorial, Drs Bertram Pitt, Professor of Internal Medicine, and Patricia Deldin, Associate Professor of Psychology and Psychiatry, both at the University of Michigan School of Medicine in the US, wrote that so far we have no evidence that positive affect directly influences heart disease risk or whether there is a third underlying factor that links the two. And neither do we know for sure whether it is possible to change positive affect and if so to what extent.

They wrote that randomized controlled trials measuring what effect increasing positive affect has on patients with cardiovascular disease are currently being done and should give us more insights on the nature of this relationship.

They said there was a “vicious cycle” linking cardiovascular disease to major depression and depression to cardiovascular disease and that cardiovascular and psychiatric researchers should do more to investigate it.

“If Davidson et al.’s observations and hypotheses stimulate further investigation regarding the effect of increased positive affect on physiological abnormalities associated with cardiovascular risk, perhaps it will be time for all of us to smile,” wrote the editors.

“Don’t worry, be happy: positive affect and reduced 10-year incident coronary heart disease: The Canadian Nova Scotia Health Survey.”
Karina W. Davidson, Elizabeth Mostofsky, and William Whang.
European Heart Journal, Advance Access published on February 17, 2010.

“Depression and cardiovascular disease: have a happy day–just smile!
Bertram Pitt and Patricia J. Deldin
European Heart Journal, Advance Access published on February 17, 2010.

Source: European Society of Cardiology.

Written by: Catharine Paddock, PhD