Stress accelerates aging and weakening of immune system: Study

Stress accelerates aging of the immune system, potentially increasing a person's risk of cancer, cardiovascular disease and illness from infections such as COVID-19, according to a new study.

The research was carried out by the University of Southern California (USC

Founded in 1880, the University of Southern California is one of the world's leading private research universities. It is located in the heart of Los Angeles.

and published June 13 in the Proceedings of the National Academy of Sciences

(PNAS).

“This study helps clarify mechanisms involved in accelerated immune aging," said Eric Klopack, lead study author and postdoctoral scholar at the USC Leonard Davis School of Gerontology

As people age, the immune system naturally begins a dramatic downgrade, a condition called immunosenescence. With advanced age, a person's immune profile weakens, and includes too many worn-out white blood cells circulating and too few fresh white blood cells ready to take on new invaders.

Immune aging is associated not only with cancer, but with cardiovascular disease, increased risk of pneumonia, reduced efficacy of vaccines and organ system aging.

But what accounts for drastic health differences in same-age adults? USC researchers decided to see if they could tease out a connection between lifetime exposure to stress, a known contributor to poor health, and declining vigor in the immune system.

They queried and cross-referenced enormous data sets from University of Michigan's Health and Retirement Study, a national longitudinal study of the economic, health, marital, family status, and public and private support systems of older Americans.

To calculate exposure to various forms of social stress, the researchers analyzed responses from a national sample of 5,744 adults over the age of 50. They answered a questionnaire designed to assess respondents' experiences with social stress, including stressful life events, chronic stress, everyday discrimination and lifetime discrimination.

Blood samples from the participants were then analyzed through flow cytometry, a lab technique that counts and classifies blood cells as they pass one-by-one in a narrow stream in front of a laser.

As expected, people with higher stress scores had older-seeming immune profiles, with lower percentages of fresh disease fighters and higher percentages of worn-out white blood cells. The association between stressful life events and fewer fresh, "naive" white blood cells remained strong even after controlling for education, smoking, drinking, BMI and race or ethnicity.

Some sources of stress may be impossible to control, but the researchers say there may be a workaround.

Improving diet and exercise behaviors in older adults may help offset the immune aging associated with stress.

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