Does happiness lead to better health and longer life? Many people, including physicians and scientists, believe that to be true. But a new study published in The Lancet sadly provides no support for that concept
Entitled "Does happiness itself directly affect mortality? The prospective UK Million Women Study," the authors (led by Bette Liu, Sc.D., M.D., Associate Professor of Medicine, University of New South Wales, Sydney, Australia, for the "Million Women Study" collaborators) looked at that question from a different perspective: they noted that poor health can cause unhappiness and poor health increases mortality.
They pointed out that previous reports of reduced mortality associated with happiness could also be due instead to the converse theory: increased mortality of people who are unhappy because of their poor health. The study authors aimed to establish whether, after allowing for the poor health and lifestyle of people who are unhappy, any robust evidence remains that happiness or related subjective measures of wellbeing directly reduce mortality.
In other words, can unhappiness cause ill health or does that proposition confuse cause-and-effect, i.e., that the major factor is that ill health causes unhappiness? The study supports the latter, not the former.
The "Million Women Study" is a prospective study of UK women recruited between 1996 and 2001 and followed electronically for cause-specific mortality. Three years after recruitment, the baseline questionnaire for the present report asked women to self-rate their health, happiness, stress, as well as feelings of control (or its lack). The study assessed the degree of happiness, self-described, among 720,000 women (average age 59) over the course of 10 years follow-up, and correlated those findings with mortality: all-cause, heart-related, and cancer-related. About one-sixth of the women reported themselves as being unhappy most of the time.
At baseline, poor health and unhappiness were strongly linked. However, after statistical adjustments were made to take into account self-rated state of health, and treatment for a variety of chronic medical conditions (hypertension, diabetes, lung/breathing problems, arthritis, and anxiety/depression) at baseline, as well as several key lifestyle and demographic factors (smoking, BMI, and deprivation in living conditions), unhappiness was not independently associated with all-cause mortality, nor death from heart disease nor cancer. (Related factors such as stress and lack of control were also not linked to mortality in this study).
So their conclusion is simple: while poor health can surely cause unhappiness, after adjusting for that relationship, happiness (or, rather, its lack) does not appear to have a direct effect on lifespan. Therefore, blaming the sick for "bringing it on themselves with their negative attitude" is not valid.
Many still believe that stress or unhappiness can directly cause disease, but they are simply confusing cause and effect," said co-author Prof. Richard Peto of the University of Oxford, in a written statement. "Of course people who are ill tend to be unhappier than those who are well, but the UK Million Women Study shows that happiness and unhappiness do not themselves have any direct effect on death rates. Nevertheless, people will still believe that stress causes heart attacks.
Caveats include: measuring "happiness" via such a survey is not very rigorous, as that emotion is often nuanced, so it's a soft measure; and this study says nothing about men.
