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NIH Record

Risk Factors Cluster To Harm Health

By Susan M. Persons

October, the month when Americans traditionally celebrate Halloween, conjures up superstitions such as "bad things occur in threes." Whether counting airplane crashes or personal setbacks, many believe that negative events tend to cluster. Now science has found a thread of truth in this common belief.

While investigating the health of those with the "bad luck" of being born into poverty, Dr. Redford B. Williams and his colleagues are testing the hypothesis that "people of lower socioeconomic conditions (SES) have an increased illness burden because the harsh conditions in which they live cause a clustering of behavioral, psychological, social, and biological characteristics that, through cellular and molecular processes, lead to increased vulnerability to pathogens."

Dr. Redford B. Williams

Williams, a professor of psychology and psychiatry at Duke University Medical Center, presented evidence of his work on psychosocial risk factors at a recent NIH Office of Behavioral and Social Sciences Research seminar. He reported, "I am now convinced, after over 25 years of personal involvement in research on psychosocial risk factors and health, that these factors, and their biobehavioral accompaniments, do not occur -- or act -- in isolation. It is becoming increasingly clear that psychosocial and biobehavioral characteristics tend to cluster in the same individuals and groups."

Although it is well known that behavioralphysical risk factors such as smoking, high blood pressure and high cholesterol levels, and sedentary life styles increase the risk of life-threatening illnesses such as coronary heart disease, Williams identified psychosocial risk factors that are also detrimental to health. "It is increasingly clear that low SES, hostile personality, depression, social isolation, and job strain also contribute to poor health, and that these psychosocial risk factors have biobehavioral accompaniments."

According to Williams, the challenge for future investigation is to understand how psychosocial and biobehavioral factors interrelate over time to contribute to life-threatening illness. Understanding this "web of interrelationships" is critical to advancing health. "While psychosocial risk factors are not specific to any one health problem, and although they probably do not directly cause disease, they lower resistance and accelerate disease processes," he said.

What is new about psychosocial risk factors? Williams reported that for "Type A" personalities the current consensus is that hostility is the key health-damaging component. Anger, cynicism, and aggressive responses are components of "hostility" that predict early mortality. Depression and social isolation are also significant contributors to the web that envelops one's health. "Even for those who are otherwise healthy, depression or a sense of hopelessness is a predictor of high death rates. And in elderly populations, low levels of perceived social support are more predictive of mortality than age itself," stated Williams.

Job strain is especially notable as a psychosocial risk factor. "A sample of women working outside the home who reported high job strain, were also more hostile, depressed, and socially isolated," Williams said. Biologic changes similar to those of depressed and hostile persons are also present in those who have high demandlow control jobs or life situations.

"Although there is strong evidence that psychosocial risk factors cluster in the same individuals," Williams reported, "it is equally important to note that they cluster in the same groups. The clustering of these risk factors in low SES populations undoubtedly worsens their health." Williams offered two plausible explanations to explain why those born into harsh living conditions have increased risk factors: First, lower SES persons learn that the world can be unpredictable, dangerous, depressing and alienating, and they cope by using food, alcohol, and nicotine to ameliorate their distress; and second, these harsh conditions reduce CNS serotonin function. A depletion of CNS serotonin in animal studies actually causes increased aggression and decreased affiliative behaviors. Decreased serotonin also plays a role in depression and increased alcohol consumption.

Perhaps most surprising, studies have shown that SES is not just relevant to the low end of the SES gradient -- that with each step down from the highest economic level, there is a step down in health. "This clearly indicates the validity of SES as a very potent predictor of health problems, especially when access to care and poor health habits are controlled," Williams said.


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