I was finally able to sit down with the NEJM article on obesity and social networks on the way to southern Africa last week. I haven’t been paying attention to what the popular media and b’sphere have been saying about the piece, but it turned out to very timely for other things I have been thinking about. Here are my take home messages and some additional thoughts on social networks and social marketing programs.
Obesity does not ‘spread’ through social networks. Rather, as the authors of the report note, what is ‘spreading’ is a change in the social norm for the acceptability of obesity (in one social psychological model, we would talk about the elasticity of the latitudes of acceptance and rejection of obesity). Their finding of a lack of any ‘spread’ for smoking behavior was the critical point missing from the first media coverage I saw. That is, behavioral imitation or modeling is likely NOT what is contributing to the observed network effect. If it were, smoking (or nonsmoking) behaviors should have shown similar patterns of spread among networks. And if you argue that social norms for non-smoking are already fairly ubiquitous, you got the point – there was no place for those norms to go. Because the acceptability of obesity is the ‘innovative idea’ here, we are seeing diffusion in action.
Close, mutual friendships – or minimal social distance – is the determining factor of whether both parties become obese: NOT living next to an obese person or being in a social network of obese people. For the people who believe neighborhoods and shared physical environments are a critical determinant of obesity, this finding should cause them to slow down: changes to the physical environment may not be the answer. It is also not just social connectedness or hanging out on MySpace sites that magnifies the power of the network to alter perceptions of obesity; it is among mutual friends when one starts gaining weight that the action starts. And remember, this was a longitudinal study, not cross-sectional, so causality is more easily inferred from the data (though I do hope someone suggests planning and launching a clinical trial to confirm these findings).
Where the authors walked off the ranch is when they proclaim that network effects can also be used to promote positive health behaviors. Here they cite a few studies that simply do not demonstrate the point at all. Adding peer and social support components to behavior change programs is not using people’s everyday social networks to promote change. It is creating a new social network (one could argue a temporary and artificial one) that provides instrumental and emotional support for the adoption and maintenance of new behaviors – they do not change people’s perceptions of reality (at least I have never seen any data to suggest that social normative changes occur as a result of these types of programs).
Changes in the perceptions of the positive or negative value of a health behavior among people with close ties in social networks is the likely precursor (or determinant) of individual behavior change or maintaining the status quo in free-living populations (not participants in a study – cf, ecological validity). That’s the important takeaway for social marketers.
And I say that as I am in southern Africa talking with PSIers about developing new HIV prevention programs based on findings that are going mainstream in The Invisible Cure. The central argument in the book is that heterosexual transmission patterns of HIV strongly suggest that the normative practice of maintaining 2 or more concurrent sexual partnerships (CSPs) over time (think of them as having minimal social distance if you like) is the core set of behaviors that fuel the HIV epidemic in some regions. In fact, the data show that these men and women typically have the same number of sexual partners over a lifetime as an American – it's concurrency, as opposed to serial monogamy, that is the distinguishing risk behavior. When these sets of CSPs overlap through one or more individuals being part of two or more networks, once HIV infection is introduced anywhere into these linked networks, it quickly spreads to members throughout all of the linked networks unless they are using condoms. There are many more nuances to the data, but the point of bringing it up here is that social networks may be the most important determinant of the spread of HIV – not individual behaviors. So do we now encourage ‘fidelity’ to regular partners and ‘abstinence’ when you are out at clubs on the weekend? Or are we looking at first changing the acceptability of these behaviors? Those, it turns out, may be the real questions we have to address next.
Then there was the post I did last December noting the results of the third clinical trial in Africa that circumcision of adult males reduced the likelihood on getting HIV by approximately 50%. In a ‘careful of what you wish for scenario’ [for me], I am now sitting at PSI where we have been working with JPIEGO on a pilot program for male circumcision in Zambia , the WHO has endorsed male circumcision as an HIV prevention strategy, and the government of Zambia has given the green light to scale up male circumcision programs in the country. Scaling up programs means creating demand for the service among sexually active men. And creating demand for male circumcision services, my head and gut tell me, will not be through some creative and expensive mass media campaigns. It is going to (should) cause us to rethink what we mean by interpersonal communications, the targets for such efforts and how to take them to scale. That’s what makes the NEJM article so much more interesting for me this week.