Stress accelerates immune aging, scientific study finds

People who experience more stress tend to have poorer diet and exercise habits

Stress, in the form of traumatic events, work stress, everyday stressors and discrimination, accelerates the aging of the immune systemwhich can increase the risk of cancer, cardiovascular diseases and infectious diseases such as COVID-19 of a person, according to a new scientific study.

The investigation, published in the prestigious magazine Proceedings of the National Academy of Sciences (PNAS), could help explain age-related health disparitiesincluding the uneven record of the pandemic, and identify possible points of intervention.

“To the extent that With the growing global population of older adults, understanding age-related health disparities is critical. Age-related changes in the immune system play a fundamental role in the deterioration of health. This study helps clarify the mechanisms involved in accelerated immunological aging,” explained lead study author Eric Klopack, postdoctoral researcher at the University of Southern California (USC), professor at the Leonard Davis School of Gerontology.

The research, published in the prestigious journal Proceedings of the National Academy of Sciences (PNAS), could help explain age-related health disparities - Photo: Colprensa/archive
The research, published in the prestigious journal Proceedings of the National Academy of Sciences (PNAS), could help explain age-related health disparities – Photo: Colprensa/archive

As people age, the immune system naturally begins to undergo drastic degradation, a condition called immunosenescence. With age, a person’s immune profile weakens, including too many spent white blood cells in circulation and too few fresh “naive” white blood cells ready to deal with new invaders. Immune aging is associated not only with cancer, but also with cardiovascular disease, increased risk of pneumonia, decreased vaccine effectiveness, and organ aging.

But, What explains the drastic differences in health among adults of the same age? The USC researchers set out to see if they could find a link between lifelong exposure to stress, a known contributor to poor health, and diminished immune system vigor.

For it, consulted and compared huge datasets from the University of Michigan Health and Retirement Study, A national longitudinal survey of the economy, health, marital status, family status, and public and private support systems of older Americans. To estimate exposure to various forms of social stress, the researchers analyzed the responses of a national sample of 5,744 adults over 50. They answered a questionnaire designed to assess respondents’ experiences with social stress, including stressful life events, chronic stress, daily life and discrimination. The participants’ blood samples were then analyzed using flow cytometry, a laboratory technique that counts and sorts blood cells as they pass one by one in a narrow stream past a laser.

Stress increased during the COVID-19 pandemic
Stress increased during the COVID-19 pandemic

As expected, people with higher stress scores had immune profiles that seemed higher, with lower percentages of new disease fighters and higher percentages of spent white blood cells. The association between stressful life events and fewer ready-to-respond, or naïve, T cells remained strong even after controlling for education, smoking, alcohol, BMI, and race/ ethnicity. Some sources of stress can be impossible to control, but researchers say there could be a solution.

T cells, an essential component of immunity, mature in a gland called the thymus, located just in front and above the heart. As people age, thymus tissue shrinks and is replaced by fatty tissue, which reduces the production of immune cells. Previous research suggests that this process is accelerated by lifestyle factors, such as poor diet and lack of exercise, which are associated with social stress. “In this study, after statistically controlling for poor diet and lack of exercise, the link between stress and accelerated immune aging was not as strong,” Klopack said.

“What this means is that people who experience more stress tend to have poorer diet and exercise habits, which partly explains why they have more accelerated immune aging. Improving dietary and exercise habits in older adults may help offset stress-associated immune aging.

In the study, people with higher stress scores had immune profiles that looked older, with lower percentages of fresh disease fighters and higher percentages of worn-out white blood cells.
In the study, people with higher stress scores had immune profiles that looked older, with lower percentages of fresh disease fighters and higher percentages of worn-out white blood cells.

Additionally, cytomegalovirus (CMV) may be a target for intervention. CMV is a common virus, usually asymptomatic in humans, and is known to have a strong effect of accelerating immune aging. Like shingles or cold sores, CMV is dormant most of the time, but it can come back, especially when a person is under a lot of stress.

In this study, statistical control for CMV positivity also reduced the link between stress and accelerated immune aging. Therefore, widespread vaccination against CMV could be a relatively simple and potentially powerful intervention that could reduce the effects of stress on immune aging, the researchers said.

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