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stress – in the form of traumatic events, job strain, everyday stressors, and discrimination– accelerates the aging of the immune system, potentially increasing a person’s risk of cancer, cardiovascular disease and diseases resulting from infections such as Covid-19, according to a new study from the University of Southern California (UCS) (USA). ).
The research, published in the Proceedings of the National Academy of Sciences (PNAS), could help explain age-related health disparities, including pandemic inequality, and identify potential intervention points.
“As the global population of older people increases, it is essential to understand age-related health disparities. Age-related changes in the immune system play a critical role in declining health,” said study lead author Eric Klopack of the USC Leonard Davis School of Gerontology. “This study helps clarify the mechanisms involved in accelerated immune aging.”
As people age, the immune system naturally begins a dramatic decline, a condition called immunosenescence. With age, a person’s immune profile weakens, including too many worn white blood cells in circulation and very few fresh white blood cells, “naive”, ready to face new invaders.
Immune aging is associated not only with cancer, but also with cardiovascular diseases, an increased risk of pneumoniato the reduction of the vaccine efficacy y al aging of organ systems.
But what accounts for the drastic differences in health in adults of the same age? The USC researchers decided to see if they could establish a connection between exposure to stress throughout life – a known factor that contributes to poor health – and the decrease in the strength of the immune system.
They consulted and cross-referenced huge data sets from the University of Michigan Health and Retirement Studya national longitudinal study of the economy, health, marital status, family situation, 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 years of age. They responded to a questionnaire designed to assess respondents’ experiences with the social stress, including stressful life events, chronic stress, everyday discrimination and discrimination throughout life.
Blood samples from the participants were then analyzed by flow cytometrya laboratory technique that counts and sorts 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 immunological profiles that appeared older, with lower percentages of fresh disease fighters and higher percentages of worn-out white blood cells. The relationship between stressful life events and fewer ready-to-respond, or naïve, T cells remained strong even after controlling for education, smoking, alcohol use, BMI, and race/ethnicity.
Some sources of stress can be impossible to control, but researchers say there may be a solution.
T cells – an essential component of immunity – mature in a gland called the thymus, located just in front of and above the heart. As people age, the thymus tissue shrinks and is replaced by fatty tissue, leading to less production of immune cells. Previous research suggests that this process is accelerated due to lifestyle factors, such as poor diet and little exercise, both associated with social stressl.
“In this study, after statistically controlling for poor diet and little exercise, the connection 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 faster immune aging.”
Improving diet and exercise habits in older adults can help counter stress-related immune aging.
In addition, the cytomegalovirus (CMV) can be a target for intervention. CMV is a common and usually asymptomatic virus in humans and is known to have a strong accelerating effect on immune aging. Like shingles or cold sores, CMV is dormant most of the time, but it can flare up, especially when a person experiences great stress.
In this study, statistical control for CMV positivity also reduced the connection between stress and accelerated immune aging. Therefore, the widespread vaccination against CMV it could be a relatively simple and potentially powerful intervention that could reduce the immune-aging effects of stress, the researchers said.
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