Although the term "social network" has come to mean connections on the Internet, in a scientific context a social network refers to relationships that occur between real people in real time, on a regular basis: friends, family and co-workers. Real human connections and the behavioral influences that result from them can be so powerful, they have given rise to an area of science called "network science," which examines how behavior and behavioral changes spread through interconnected groups of people. These include health-related behaviors and conditions ranging from weight gain, smoking and smoking cessation, sleep, drug and alcohol use to emotional wellbeing and longevity.
One landmark study on obesity published in The New England Journal of Medicine in 2007 found that having just one friend who becomes obese can increase a person's chance of becoming obese by 57 percent, and that weight gain isn't only influenced by a person's friends, but by friends of friends who have gained weight (3 degrees of separation). Conversely, as a Weight Watchers member will tell you, meeting regularly with a group of people who are losing weight can make a significant difference in keeping your own diet on track. A social network not only affects the speed at which people adopt new habits but also the extent to which they stick to them. The more successful any social structure is at building and maintaining relationships, the longer it will produce healthy benefits for its members.
Does that mean that relationships can be as much of a factor in good health as cholesterol, blood pressure and BMI? Although evidence-based research on psychosocial processes and positive health outcomes has become prevalent only within the past decade and a half, the results are persuasive.
Physical health
Data from 148 studies on health outcomes and the social relationships of more than 300,000 men and woman across the developed world determined that people with strong social connections had an average 50 percent higher chance of survival in the seven and a half years following the study than people with poor social ties. The results didn't vary significantly by sex, age or health status.
In another well-known study on the influence of social connections to the workings of the immune system, hundreds of healthy volunteers were exposed to the common cold virus, then quarantined for several days. The participants with more social connections from different contexts - such as work, sports and spiritual activities - were less likely to get a cold than volunteers who were more socially isolated. Simply put, the immune systems of people with a variety of friends tended to work better, possibly due to lower levels of stress hormone release by the well-connected people.
Mental health
How do personal connections impact physiological functions? Many regulatory systems in the body, especially blood pressure, metabolism and stress hormones, have all shown to be affected by relationships and the quality of social interaction. Lab studies indicate that in stressful situations, a person's blood pressure and heart rate will spike less if someone is with them. (On a related note, see my blog post on commuting in Los Angeles.) In one study, children who were allowed to speak to their mothers after a stressful event experienced a spike in the levels of a neurotransmitter that decreases hormonal stress response (oxytocin), compared to children who weren't allowed to talk to their mothers. Brain imaging studies have also revealed neurological differences between people who were alone and those who had support. As for cultivating a strong and supportive system in order to promote good health, let's not forget the benefits of sitting down to a regular family dinner together.
Public health
Beyond the ability of social networks to influence the health of an individual, they can also influence public health. The thinking is that "social connectors" - people who have more than an average number of friends and would likely be exposed to more germs - would probably also be first to contract contagious diseases like the flu. Tracking the "social connector" would serve as an early detection system for epidemics, indicating the people to vaccinate to slow the spread of a particular disease. A Harvard study that used electronic medical records at the university health service to track the spread of the H1N1 flu showed that an outbreak of flu developed approximately two weeks earlier in a group of students who were all identified as "friends" of students, than in a group of randomly selected participants. The concept of social "connectors" playing an important role in creating social epidemics was beautifully described by Malcolm Gladwell in The Tipping Point.
The care and feeding of healthy relationships
Since our ability to make and maintain human connections has such an impact on our physiological, emotional and even societal health, maybe there should be a box on medical charts after cholesterol, blood pressure and BMI called "Relationships." Are they positive? Are they helping or hindering our own good health? Are we exercising them properly? Research shows it's worth the time and effort to cultivate healthy relationships and keep them up and running.