Stress can wear you down and make you old. Everybody knows that, and so do our cells.
For ages, the biggest stresses were infection, starvation, malnutrition, exhaustion, trauma, toxins and exposure to the elements. They damage an organism’s cellular machinery and trigger a cascade of biochemical events (such as inflammation) that can do harm as well as good.
Modern human beings have traded some of those ancient stresses for new ones, including poverty, financial pressure, racial discrimination, gun violence and child abuse.
Do those social stresses damage the body the way physical ones do? Research is starting to answer the question.
“It’s not clear that the mediators of physiological stress and psychological stress are different. Both, in the end, have molecular underpinnings,” said Richard J. Hodes, director of the National Institute on Aging at the National Institutes of Health.
The passage of time, some chronic diseases such as diabetes, obesity, and certain unhealthful behaviors such as inactivity and smoking are all associated with short telomeres, the protective caps at the ends of our chromosomes that are indicators of “biological age.” Telomere shortening is both a cause and a consequence of aging.
Shorter telomeres have also been detected in people who care for years for an ill child or someone with Alzheimer’s disease; people in chronic poverty; victims of childhood trauma who have post-traumatic stress disorder; and women who had been in an abusive relationship for an average of 4.8 years.
A study published last year found that social stress can have similar effects on a different measure of biological aging: the methylation pattern of DNA. (Methylation is the attachment of a molecule called a methyl group on the outside of the DNA chain.)
Researchers used a methylation-based “clock” to estimate the biological age of 100 black women in the United States who have been followed since 1997. All were primary caregivers in their families, their average chronological age was 49, nearly three-quarters lived in large cities, and about 35 percent of the families’ incomes were below the poverty line.
About 70 percent of women whose family’s per-capita income was less than $3,900 per year showed “accelerated aging” compared with the group average. Women in families with per capita incomes of more than $15,000 showed decelerated aging. Higher-than-average biological age was also strongly associated with financial pressure, defined as difficulty paying monthly bills.
This effect of poverty and social stress on the body has been termed “biological weathering.”