Yesterday, that headline was picked up by the BBC News, Wall Street Journal, and Science Daily, and will undoubtedly continue travel through the blogosphere for weeks to come. A study conducted by researchers at the University of Chicago and reported in the journal Cancer Prevention Research (click here for the abstract) began six years ago when a team, led by a cancer specialist and a biobehavioral psychologist, raised two groups of mice that were genetically predisposed to develop breast cancer. Some lived with other mice and some lived alone. After the same amount of time, the isolated mice grew larger breast cancer tumors. Mice in the "stressful environment"--isolation--also behaved differently and had higher stress hormone levels.
This research is consistent with the a range of studies epidemiological studies done over the last several decades on social isolation, "social integration"--having lots of different kinds of people in your life, not just intimates--and the "stress-buffering" effect of social support on humans as well as mice. As we report in Consequential Strangers, mothers in Guatemala who were paired with a doula, a "birthing companion" who was neither husband nor close friend, had fewer complications in childbirth than women who had to go it alone. They were also more responsive to their babies. Other studies show that the mere act of describing a difficult even in detail can ease stress over time. Even though no one knows precisely how social factors work on physiology, doesn't it make sense that going through our own or a loved one's crisis requires support? It's often a matter of survival: In another study, when rats who had been previously given electric shocks were returned to the shock box, they naturally showed signs of fear. But the fear response--rapid breathing and higher temperature--was not as strong when another rat was present, particularly one who hadn't been shocked.
What are the practical implications of these studies? You're more likely to stay healthy if you have social support--loved ones and casual relations. When you're sick, the kind of help you need often comes from an outsider--a consequential stranger--because you and your family are living in a shock box. People who lack this kind of support are clearly at greater risk of disease.