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Medicine in small doses

Enshrined in the United States Declaration of Independence, drafted by Thomas Jefferson in 1776, ‘The pursuit of happiness’ is something we all strive for in an attempt to improve the quality of our life and general well-being. Happiness is often perceived as an important ingredient of having a good life and it includes qualities such as pleasure, joy, exhilaration, bliss, contentedness, delight, enjoyment and satisfaction. Moreover, in the pursuit of happiness, individuals may follow either the hedonistic approach of seeking pleasure and avoiding unpleasant experiences or the eudaimonic approach to living life in a full and deeply satisfying way (Ryan and Deci. Annu. Rev. Psychol. 2001; 52: 141–66). No matter how you may wish to define happiness it is usually considered to be synonymous with a healthy life and as a consequence improved longevity. This may not be so? In an attempt to answer the question: Does happiness itself affect mortality? Liu et al. (Lancet, http://www.dx.doi.org/10.1016/ s0140-6736(15)01087-9), using data from the UK woman millions study (www.millionwomensstudy.org), determined that in middleaged women (median age of 59 years) poor health can cause unhappiness but after allowing for this association and adjusting for potential confounders, happiness-related measures of well-being do not appear to have any direct effect on mortality. The million women’s study recruited 1.3 million women aged 50– 69 years from 1 May 1996 to 31 December 2001 through the national breast screening programmes of England and Scotland. This cohort of woman has been followed over the subsequent years by electronic record linkage recording the causes of any deaths. At recruitment and every 3–5 years, subsequently women were posted a questionnaire asking about socio-demographic factors, lifestyle and health. At baseline, 3 years after recruitment, the women were asked: ‘How often do you feel happy?’ and about related subjective measures of well-being including: being in control, being relaxed or not unduly stressed. Women were followed for a minimum of 9.5 years after completing the questionnaire and in the subsequent analysis women who at baseline already had heart disease, stroke, cancer or chronic obstructive airways disease were excluded. This left 719 671 women who formed the basis of the study with 39% reported being happy most the time, 44% usually happy and 17% unhappy. In the crude analysis, adjusted only for age, unhappiness remained associated with increased mortality; this excess risk was partly accounted for by the associations with various personal characteristics. Poor health at base line was usually associated with unhappiness but once this was adjusted for self-related health, unhappiness was no longer significantly associated with all cause mortality. However, being treated for depression and anxiety was strongly associated with self-reported unhappiness but when adjusted against unhappiness did not seem to be related to mortality. Although poor health increases mortality, so unhappiness is associated with increased mortality. Additionally, unhappiness may correlate with some adverse lifestyle choices such as smoking, obesity and lack of exercise. After allowances for all these associations, this large robust prospective study concludes there is no evidence that happiness itself reduces cardiac, cancer or overall mortality. But, is there any good news from the study? The strongest sociodemographic and lifestyle correlates of being generally happy were increasing age, having fewer educational qualifications, doing strenuous exercise, not smoking, living with a partner and participating in religious or other group activities, which intuitively makes sense. Moreover, the relationship between happiness and sleep revealed that women reporting about 8 h of sleep were the happiest. Needless to say, the study was only on women and there is some evidence that happiness–mortality association appears to be to some extent gender specific with higher positive effects reported in men than in women. However, men and women probably define happiness differently which may explain at least partially the genderspecific differences for the associations between happiness medical outcomes including mortality. This study does focus on middleaged women and research about happiness of older adults should focus on medical outcomes rather than mortality, particularly the incidences of dementia and the potential association between happiness and incidences of cognitive decline, which is of greater relevance to the elderly individuals (Barreto and Rolland. Lancet, http://www.dx.doi.org/10.1016/s0140-6736(15)01222-2). Indeed Liu et al. has demonstrated that happiness is associated with healthy lifestyles such as regular exercise and abstinence from smoking which are in turn are protective factors against dementia. So what is the take-home message? Whereas, the pursuit of happiness may not necessarily reduce one’s mortality, following a healthier lifestyle increases happiness which may potentially reduce the age-related cognitive decline and dementia. That depression and anxiety may be linked with increased unhappiness supports the axiom, don’t worry be happy!