Dynamic spread of happiness in a large social network: longitudinal analysis over 20 years in the Framingham Heart Study.

This study shows that happiness spreads among people within social networks. The goal of palliative care is to improve the wellbeing and quality of life of patients, which is a major component of their happiness. This in turn contributes to happiness of others, making palliative care an element of public health.

Happiness is a fundamental object of human existence and an element of health. The majority of research conducted so far in this field has focused on finding individual determinants of happiness such as socio-economic situation, genetic factors, illness etc. {1}. None of these studies, however, has addressed a possibility that happiness of others in a personal network may be a key component of one's own happiness. It has also been largely unknown whether happiness might spread. This study was conducted using an "offspring cohort" of the "original cohort" of people enrolled in the Framingham Heart Study. 4739 individuals were included as well as their network of family members, friends, neighbors and co-workers. Happiness was measured using four items from the Center of Epidemiological Studies depression scale that assessed participants' feelings during the previous week: "I felt hopeful about the future", "I was happy", "I enjoyed life", "I felt that I was just as good as other people". "Happy" was defined as having a perfect score on all four items. Changes in happiness were analyzed over time. The results revealed that happy people tend to be connected to one another, which results from the spread of happiness, not from a tendency of people to associate with similar individuals. Moreover, this association proved to be significant for up to three degrees of separation. It diminished with time and geographical distance and did not show to be significant for co-workers. The authors speculate that the emotion of happiness might have evolved in order to enhance social bonds. It seems that palliative care has intuitively understood this phenomenon as it has always been based on the premise that the wellbeing of patients needs to be understood in the context of their social network {2}. Now we have evidence that supports this claim and furthermore makes it clear that, by relieving the suffering of others, we contribute to potential spread of happiness through their social networks. Our role in such context seems much bigger and seems to be expanding beyond the benefits of treatment of an individual patient. As a result, palliative care can be understood as an element of public health {3}. One of the major unanswered questions remains, i.e. what is the exact mechanism with which happiness is spread? Is it a function of social interactions, e.g. happy people sharing their good fortune? Or can the causative mechanism perhaps be explained by the field of psychoneuroimmunology? This must be the subject of future studies.

References: {1} Kahneman et al. Science 2006, 312:1908-10 [PMID:16809528]. {2} WHO Definition of Palliative Care. Available at: http://www.who.int/cancer/palliative/definition/en Accessed on January 12, 2009. {3} Stjernswärd J, J Public Health Policy 2007, 28:42-55 [PMID:17363935].

This article clearly shows that over a period of 20 years, happiness of persons is not a province of the isolated individual, but depends on the number and (social and geographical) closeness to other happy persons in the person's social network.

Given the compact nature of the Framingham Heart Study, participants often link to each other by different types of social ties (family, friend, neighbour, colleague). Among 51,240 persons starting the 1983-2003 cohort, an average of 10.4 social ties with another participant of the Framingham study was reported: 83% with a spouse, 87% with a sibling, 45% with a friend, 39% with a coworker and 10% with a neighbour. Happiness was assessed by a subset of four questions from the Center for Epidemiologic Studies Depression Scale (CES-D) that have shown to have a good correlation with other happiness measures. Network analyses showed that happy people cluster together, and longitudinal analyses using generalised estimating equation procedures showed that the chance of a person to be happy over a period of 20 years increases when the person has a large number of social ties with happy people, when there is a happy person within a social distance of three social ties, and when the geographical distance to a happy social tie is shorter. Of course, it is acknowledged that the assessment of the social network might be incomplete as social ties did not necessarily participate in the study. Notwithstanding, over a period of 20 years, happiness seemed to spread over different social ties, even if the person is not in direct tie with the index person. This study points to the importance of the quantity and quality of a person's social network. Also, in healthcare, providers should realize their happiness can spread to patients, and patients can be stimulated to actively improve their social network.