The common cold: that bugbear of medical mischief. It infects everyone from time to time, irritating us and making us less productive, as if to say “for all your knowledge, for all your technology, you’re not that smart. I’ve still got your number; you still haven’t got me licked.”
The scientific world has recently made substantial headway against this common scourge, thanks to the work of Sheldon Cohen, Carnegie Mellon University. Cohen delivered the James McKeen Cattell Fellow Award Address at the APS Annual Convention in Atlanta. The James McKeen Cattell Fellow Award is given to psychological scientists for their outstanding contributions to applied psychology.
Cohen, an APS Fellow and Charter Member, presented a clear and compelling set of experimental studies demonstrating that the incidence of cold infections is strongly affected by psychological and social factors, most importantly, social stress and social support.
Cohen and his colleagues used a simple, powerful methodology to examine the influence of psychological factors on the cold. During the initial time period in which a participant was in the study, psychosocial factors, such as stress, were measured. In the second time period, participants were brought into the lab and quarantined for six days. Toward the beginning of the quarantine, the participant is exposed to a cold virus. The researchers then look for a relationship between the psychosocial factors and who contracts the cold.
The results revealed a clear relationship between the amount of life stress reported and the percentage of people who caught the cold. As stress increased, so did the incidence of the cold, and this relationship was strongly linear, meaning that for each increment of additional stress, there is an additional increment of susceptibility to the cold.
Why stress led to this change was still unclear. Neither differences in health practices nor immune function mediated the relationship between stress and susceptibility.
In a follow-up study, the result was replicated with an improved measure of cold infection. Cohen also obtained more information about the types of stress people were experiencing, and discovered that chronic stressors produce much more susceptibility than acute, short term stressors. Interpersonal conflicts and work-related stress due to over or unemployment also led to more infections than other forms of enduring stressors.
Psychological factors, such as stress, are a good predictor of who will get a cold in a controlled environment. Other psychosocial factors are also important. For example, individuals with few high-contact social roles had more colds, and the less diverse their social network, the more colds they had as well.
Cohen and his colleagues questioned how an individual’s personality might affect cold susceptibility. It wasn’t long before they found that introverts get sick more often, although this didn’t explain the social role effect fully.
Health practices also explained some of the differences in susceptibility, though some may come as a surprise: alcohol consumption had an effect, but it was the nondrinkers who had twice the risk factor for the cold compared to drinkers. Lack of exercise also doubled the risk factor, and smoking increased it threefold. Poor sleep and vitamin C intake are also related. Yet, none of these differences explained the effect of stress, meaning that stress has its impact via something other than health-related behaviors.
Sociable people do get fewer colds, tend to have better health practices, and better and more social interactions. Results of a large-scale follow-up study discounted a cause-effect relationship with the levels of social content and risk of getting a cold. Cohen suggested other intervening factors may be important to look at, such as genes, a more specific measure of health behavior that might show a mediating effect, or that one’s mental picture of their social life may play more of a role than actual interactions.
Reducing stress, particularly chronic, interpersonal, and work-related stress should lower susceptibility. That, combined with good health practices and a high-contact and diverse social life should reduce the incidence of colds significantly, compared to leading a life with more stress and less social interaction.
Editor’s Note: Coverage of other award addresses at the APS Annual Convention will appear in upcoming issues.