Do biomarkers explain why some people are happier than others?

Alex Bryson and Petri Böckerman
What makes us happy? It sounds a simple enough question. Intuitively, we know what we like – being with friends, going to the movies. In the moment, we know what’s likely to make us happy. Evidence from app-devices that ding people at random moments mostly confirm the rank order of events that make us happy: sex and intimacy comes top, being sick in bed comes bottom.
Work comes second bottom. This might come as a surprise to most, though not to economists who have long thought that work is a disutility (it fails to satisfy human wants) and, in the moment, we’d rather be doing other things. The evidence also confirms we’d usually rather be outdoors in green spaces, and doing things with friends. We also know a lot about the things that go to make a fulfilling worthwhile life such as having a family. Paid work scores highly on the eudemonic (well-being) dimension of happiness too.
But for any given event or scenario some people are happier than others. Danes score themselves more highly than Finns, even when asked to imagine the same vignette. And if one plugs in “who you are” to a happiness equation (econometrically speaking, by plugging in a person fixed effect) this accounts for much of the variance in happiness between people, and how our happiness shifts in response to events. Why should this be? This is where things get trickier: we know very little about what’s in the “black box” that explains variance in the happiness between people.
Part of the explanation may lie in how we are made up, biometrically. Biomarkers or biological markers, are objective indicators of one’s medical state such as blood pressure and pulse, which can be measured accurately and reproducibly. Some psychiatric treatments imply a link between certain biomarkers and ill-being. For instance, in cases of extreme depression psychiatrists sometimes prescribe drugs intended to minimise mood swings by altering the chemical balance in the body/brain. But population-wide studies examining links between biomarkers and happiness are rare, mainly because very few studies contain both biomarkers and individuals’ happiness. A study of over-50s in England found a negative independent association between happiness and circulating triglycerides, the main source of body fat in humans. It was the only association between a biomarker and happiness common to men and women.
There are good reasons to expect a negative association between triglycerides and happiness since triglycerides are linked to poorer physical health and other metabolic risk factors such as elevated blood pressure, as well as life-style variables like physical inactivity. The over-50s study does a good job of controlling for many of these factors but in a cross-sectional study it is not easy to discount the possibility that the association is driven by omitted variables. Cross-sectional data also make it difficult to discern the direction of any causal linkage.
We thought the issue sufficiently important to revisit it using longitudinal data for a population of young Finns. This new study, published today, is unusual in obtaining measurements on eight biomarkers in childhood (triglycerides, body fat, height, pulse, systolic blood pressure, diastolic blood pressure, insulin, and creatinine), together with happiness in adulthood. Happiness is measured with a standard statement “In general, I feel happy”, with responses recorded on a 5-point scale from “not agree” to “agree”. Having accounted for a very rich set of confounders including age, sex, body size, family background, nutritional intake, physical activity, income, education and labour market experiences we find no associations between the eight childhood biomarkers and adult happiness. (Although we do find a negative relationship between an additional triglyceride and happiness the finding is not robust to the use of later triglyceride measurements). We conclude that none of the eight biomarkers measured in childhood predict happiness robustly in adulthood. In other research we have shown that childhood biomarkers are predictive of other adult outcomes, namely earnings and employment, but we found no such relationships with adult happiness.
Biomarkers may be strongly associated with happiness in cross-section. For example, body fat can affect happiness through one’s self-perception, but childhood indicators do not predict adult happiness. Our study is not the definitive final word on the subject. It is possible that happier people function or behave in such a way as to induce changes in their biomarker readings in a way that we cannot observe.
For instance, happier people behave in healthier ways, for instance with respect to food intake, thus confounding our results. There may also be many biomarkers other than the eight we study that could matter for happiness. Biomarkers and happiness could be co-determined by a third factor, such as genetic predispositions, which are unaccounted for in most data sets that are available. Unobserved traits related to genetic endowment are potentially very important. De Neve et al. (2012) show that around one-third of variation in life satisfaction is explained by genetic variation. It may be only a matter of time before studies identify the biological factors robustly linked to human happiness. The subject is an important one given the value individuals attach to happiness and its value in terms of productivity and human health.
Böckerman, P., Bryson, A., Viinikainen, J., Hakulinen, C., Hintsanen, M., Pehkonen, J., Viikari, J. & Raitakari, O. (2017). The biometric antecedents to happiness. PLoS ONE, is published today.
Photo: Happiness by Shefa Ahsan via Creative Commons