Their groundbreaking research shows that the most important predictor of health-even more than diet and exercise-is the number of groups to which you belong, particularly if you have strong relationships within them. A recent study by Columbia University of 655 stroke patients found that those patients who were socially isolated were twice as likely to have another stroke within five years compared with those who had strong social relationships.
Isolation is the greatest risk factor-more so than having coronary artery disease or being physically inactive. In fact, the health risk of social isolation was comparable to being
a smoker, having high blood pressure or being vastly overweight (Neurology, 2005; 64: 1888-92).
"As a rough rule of thumb," wrote Harvard political scientist Robert D. Putnam in his book Bowling Alone (New York, NY: Simon & Schuster, 2002), "if you belong to no groups but decide to join one, you cut your risk of dying over the next year in half."
Ironically, catching infections appears to have far less to do with exposure to germs and much more to do with the state of your social life. Being socially isolated appears to make you more susceptible to infections, large and small. Psychologists at Carnegie Mellon University in Pittsburgh, PA, found that those who had the widest and most diverse number of social roles remained far more robustly immune to the common cold. On the other hand, the least sociable people studied were twice as likely to come down with colds as those who were the most sociable (JAMA, 1997; 277: 1940-4).
The stress of isolation
Social support (or lack of it) may even affect the progression of cancer. Chicago scientists gathered together infant mice that were genetically predisposed to breast cancer and identical in every way, and divided them into two groups. One batch was raised within a group of mice, while the others were raised on their own. After studying the development of mammary tumours over time, the researchers found that the mice that had been isolated grew far larger tumours.
When the researchers studied the gene expression in mammary tissue of the two sets of mice over time, they found altered levels of genetic expression of metabolic pathway genes favouring tumours in the isolated mice (Cancer Prev Res [Phila Pa], 2009; 2: 850-61). The environment had altered the way in which their genes were 'turned on'.
The mice were also found to have developed a disrupted hormone response and behaviour indicative of chronic stress.
Suzanne Conzen, associate professor of medicine at the University of Chicago and part of the research team, concluded that "the social environment, and a social animal's response to the environment" can alter gene expression-that is, turn them on or off-in a wide variety
of tissues in the body.
Although this study may not necessarily apply to humans, a good deal of research has shown that our bodies react similarly to the stress of isolation. Natural-killer (NK) cells-the immune system's front line of defense against cancer and many viruses-are profoundly reactive to stress in our lives, particularly social stressors (Neuropsychobiology, 1993; 28: 87-90; Psychosom Med, 1998; 60: 290-6). Indeed, large dips in NK cell numbers and activities have been seen immediately after interpersonal problems such as separation or divorce (Psychosom Med, 1987; 49: 13-34), and even during arguments or minor conflicts (Psychosom Med, 1993; 55: 395-409).
Nevertheless, numerous clinical studies show that social contact and a strong support system can counteract the effects of stress, and boost the activity and number of NK cells (Psychosom Med, 1995; 57: 23-31; Psychosom Med, 1996; 58: 264-72; Br J Med Psychol, 1988; 61: 77-85).
Similarly, social stress can affect the hypothalamus- pituitary-adrenal gland axis, one of the chief regulators of the body's ability to fight off disease. Psychologist David Spiegel and colleagues found a link between marital discord and negative affects on the cortisol rhythms of the body, now considered to be a risk factor for early breast-cancer mortality (J Natl Cancer Inst, 2000; 92: 994-1000).
So far, many of the studies have used animals, which may not be entirely applicable to us. Nevertheless, they've found that social support during stress entirely alters the body's response. In one such study, squirrels showed elevated levels of blood cortisol when on their own. However, these levels were reduced by 50 per cent when the animals were joined by one other squirrel, and by 100 per cent when they were amidst five friends (Levine S et al., 'Psychoneuroendocrinology of stress: A psychobiological perspective,' in Brush FR, Levine S, eds. Psychoendocrinology. New York, NY: Academic Press, 1989).
Whether squirrels or humans, the more social we are, the merrier-and healthier-we will be.
WDDTY Volume 20 Issue 10