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Happiness, well-being do not directly affect mortality

Unhappiness and stress do not increase mortality and happiness or feeling relaxed or in control do not reduce mortality, according to data published in The Lancet.

Bette Liu, PhD, an epidemiologist and associate professor at the University of New South Wales, Sydney, Australia, and colleagues explained that previous reports have mistaken cause and effect, when there is really a noncausal association between unhappiness and increased mortality. Interpreting such data is challenging, particularly in regards to reverse causality and lifestyle factors that may attribute to unhappiness.

"Happiness and related measures of well-being are reportedly associated with reduced mortality, particularly from heart disease," Liu and colleagues wrote. "Postulated mechanisms to account for this association include the possibility that happiness might itself cause biological changes, such as in serum cortisol concentration or immune function, that could in turn affect mortality."

The researchers warned that challenges exist in interpreting the data, specifically in regards to reverse causality and lifestyle factors.

Liu and colleagues evaluated questionnaire data from participants in the Million Women Study, who answered questions about lifestyle, sociodemographic factors and health, including their happiness, well-being and stress level. The participants were followed for all-cause mortality, as well as death from ischemic heart disease and cancer.

After excluding women with life-threatening diseases at baseline, Liu and colleagues were left with a population of 719,671 women with a median age of 59 years. Data showed that 4% (n=31,531) of the population died during the follow-up period.

In the baseline questionnaire, 39% (n=282,619) of participants reported being happy most of the time, 44% (n=315,874) reported being usually happy and 17% (n=121,178) reported being unhappy.

The researchers found that poor health was strongly associated with baseline unhappiness. After they adjusted for self-rated health, sociodemographic factors, lifestyle factors and health indices, that association no longer existed for all-cause mortality (RR = 0.98; 95% CI, 0.94-1.01), ischemic heart disease mortality (RR = 0.97; 95% CI, 0.87-1.1) and cancer mortality (RR = 0.98; 95% CI, 0.93-1.02).

"It has been suggested that related subjective measures of well-being, including being in control, not being unduly stressed, or having positive or negative attitudes to life, could independently affect mortality," Liu and colleagues wrote. "However, just as for happiness, these associations were wholly accounted for by personal characteristics and ill health at baseline — after adjusting for these factors, any association with mortality was eliminated. We conclude that happiness and unhappiness have no material direct effect upon mortality." – by Chelsea Frajerman Pardes

Disclosures: The authors report no relevant financial disclosures.