Social butterflies and the law of correlation

When it comes to interpreting the findings of health and lifestyle studies, there’s one axiom to keep firmly in mind: Correlation does not equal causation.

Got that? Correlation does not equal causation. In other words, just because two things appear to be associated with each other, it doesn’t necessarily mean one of them caused the other.

This principle leaped rather strongly to mind this week after reading a new study about the impact of social relationships on mortality. The study, which was published in the latest issue of PLoS Medicine, analyzed 148 previous studies that examined the effect of social relationships and whether people who were well integrated socially lived longer than those who were more isolated.

It’s an intriguing question to ask. As the study’s authors point out, there’s been a trend in industrialized nations for people to be less socially connected. It’s logical to wonder whether we’re headed in the wrong direction or whether increasing social isolation might translate into a negative effect on physical and mental health.

After analyzing a large collection of prior studies and calculating the “effect size” of social integration on mortality risk, the researchers concluded that people with what they termed “adequate social relationships” had a “50% greater likelihood of survival compared to those with poor or insufficient social relationships.” What’s more, the effect appeared to be comparable to quitting tobacco and was even stronger than well-established risk factors such as obesity and lack of activity.

The study describes the implications:

Physicians, health professionals, educators, and the public media take risk factors such as smoking, diet and exercise seriously; the data presented here make a compelling case for social relationship factors to be added to that list. With such recognition, medical evaluations and screenings could routinely include variables of social well-being; medical care could recommend if not outright promote enhanced social connections; hospitals and clinics could involve patient support networks in implementing and monitoring treatment regimens and compliance, etc.

The authors conclude: “Social relationship-based interventions represent a major opportunity to enhance not only the quality of life but also survival.”

It’s all certainly very intriguing, but I’m not quite ready yet to run out and make 10 new friends just so I can tack on an extra few years of life. Despite all the data and the number-crunching, this study did not demonstrate conclusively that social integration in and of itself is a protective factor against early mortality. Sure, it showed an association – but this is not the same thing as proof.

In some ways, the study actually raised more questions than it answered. How should “adequate social integration” be defined? Are strong family relationships better for our health than friendships with peers? Are 10 friends better than two or three? Which is more protective – a large circle of casual acquaintances or a small handful of close friendships?

It’s entirely possible that people who are less socially integrated and die sooner are in poorer health to begin with – and that their poorer health status is the reason they aren’t as socially active. (The researchers said they controlled for this but it’s always tricky to draw conclusions from multiple studies, all of which might have been designed in different ways.) Or maybe there’s some other factor that hasn’t been accounted for, such as particular physical, emotional or behavioral characteristics that might influence someone’s likelihood of being both socially engaged and living longer. Perhaps social engagement is a surface expression of something deeper, such as a sense of personal belonging, purpose and meaning.

It’s also interesting to note the study’s implicit bias: the assumption that social integration is almost always beneficial and should be vigorously pursued for better health. American culture is fundamentally open and gregarious – we’re the ones who gave the world Facebook, after all – and extroversion has come to be viewed as the norm. When this is the case, people who are introverted and more comfortable with solitude can be seen as not quite right or somehow in need of fixing. Researchers might conclude we should all be more socially engaged because it’s good for us, but an introvert could well find this stressful and not particularly beneficial to his or her well-being. In fact, more than a few social observers have lamented that Americans, with their dependence on cell phones and 24/7 access to the Internet, are becoming too connected.

It all seems like an area ripe for further research. Just remember, though: If it appears that people who are more socially engaged tend to live longer, it doesn’t automatically follow that their social life is the reason for their longevity. Correlation does not equal causation.

West Central Tribune file photo by Bill Zimmer