Social Media and the Science of Health Behavior

2135 Social influences are a primary factor in the adoption of health behaviors. Compliance with diet and nutrition programs, adherence to preventive screening recommendations, and maintenance of exercise routines all can depend on having contact with friends and family who also engage in these behaviors. In addition to a great deal of literature on peer effects, recent studies of large network data sets have made important advances in our understanding of how social networks influence the collective dynamics of health behavior. Research has shown that social influences can affect collective health outcomes ranging from epidemic obesity to smoking behaviors, which have important consequences both for theoretical models of social epidemiology and for the practical design of interventions and treatment strategies. These findings have direct implications for research aimed at understanding how social influences on dieting, exercising, medication use, and getting screenings can impact behavior change affecting cardiovascular disease. The large number of health domains affected by recent research on the spread of behaviors has made social diffusion a topic of growing interest for an increasing variety of researchers and practitioners who are concerned with understanding the social dimensions of health. This article discusses the development of new methods that use social media to study these health dynamics. Although there is widespread theoretical and practical interest in understanding how social influences affect healthrelated behaviors, empirical studies of the social dynamics of health face important methodological challenges. Large observational studies of population health have faced the limitation that they are unable to address problems of causal identification. Extant studies have been able to show conclusively that health-related traits such as smoking and weight gain correlate with social ties in a network, yet the data do not provide a clear assessment of the degree to which social network ties directly influence behaviors versus reveal shared exposure to common influences. Correlations of traits with social network ties can occur because people who are friends are exposed to the same media signals (ie, exogenous information), because connected individuals live in the same neighborhoods (ie, geographic constraints such as living near the same restaurants and gyms), because people who already have similar traits form social ties with one another (ie, choice homophily), or because connected individuals influence one another to adopt similar behaviors (ie, social influence). Although new techniques are being developed to discriminate between each of these causal mechanisms, determining the relative impact of these factors is very difficult and is made even more complicated by the lack of reliable data both on the timing of behavior change and on the actual social network structure of a given population. These difficulties motivate the need for new methods that can allow health researchers to identify the role of social networks in the real-time dynamics of behavior change. The goal of this article is to demonstrate that the rapid growth of peerto-peer social media presents an important new resource for addressing these empirical challenges. Increasing levels of public participation in a diverse range of health-related social media create a new population of subjects whose natural, everyday engagement with health behaviors can be monitored and scientifically explored with a rapidly expanding repertoire of social technologies. Building on these new capacities, recent research has begun to study how social media can be used to experimentally evaluate the effects of social influence on behavior change. This approach to using social media entails a shift in focus from the interpersonal dimensions of social interactions to the community-wide effects of social network structure on the spread of behaviors through online populations.