The study utilised data for 4,478 participants of a nationally-representative survey to look at the association between happiness, assessed in the year 2009, and subsequent likelihood of dying due to any cause, until 31 December 2015. The survey was focused on individuals' aged 60 years and older living in Singapore.
Happiness was assessed by asking the survey participants how often in the past week they experienced the following: 'I felt happy', 'I enjoyed life' and 'I felt hope about the future'. Their responses were considered in two distinct ways; a 'happiness score', and a 'binary happiness variable - Happy/Unhappy'. A wide range of demographics, lifestyle choices, health and social factors were accounted for in the analysis.
The researchers found that among happy older people, 15% passed away until 31 December 2015. In contrast, the corresponding proportion was higher, at 20%, among unhappy older people. Every increase of one point on the happiness score lowered the chance of dying due to any cause among participants by an additional nine percent. The likelihood of dying due to any cause was 19 percent lower for happy older people. Further, the inverse association of happiness with mortality was consistently present among men and women, and among the young-old (aged 60-79 years) and the old-old (aged 75 years or older).
"The findings indicate that even small increments in happiness may be beneficial to older people's longevity," explained Assistant Professor Rahul Malhotra, Head of Research at Duke-NUS' Centre for Ageing Research and Education and senior author of the paper. "Therefore individual-level activities as well as government policies and programs that maintain or improve happiness or psychological well-being may contribute to a longer life among older people."
June May-Ling Lee, a co-author, added: "The consistency of the inverse association of happiness with mortality across age groups and gender is insightful - men and women, the young-old and the old-old, all are likely to benefit from an increase in happiness."
Interest in the pursuit of happiness to improve the health of older people has been growing. While previous studies have linked happiness or positive emotions with a range of better health outcomes, the evidence on the effect of happiness on living longer has been inconclusive. Many of these studies do initially observe a greater extent of happiness to be associated with a lower likelihood of dying, but this link disappears once differences in demographic, lifestyle and health factors between those less and more happy are accounted for.
This is one of the few Asian studies to have assessed the association between happiness and mortality among older people, while accounting for several social factors, such as loneliness and social network, therefore extending the generalisability of the findings to non-Western populations.