Stress ages the immune system faster

June 15, 2022
Stress ages the immune system faster

Immune aging increases a person’s risk of developing diseases such as cancer and cardiovascular disease, as well as increased susceptibility to infection. Researchers from the University of Southern California (USC) have showed that stress plays a crucial part in aging of the immune system in same-age adults, and propose a little-known therapeutic intervention.

With aging comes a natural decline in the immune system, a condition called immunosenescence. Immunosenescence includes too many worn-out white blood cells circulating and too few fresh, “naive” white blood cells (T cells) ready to take on new invaders.

[T-cells are a critical component of immunity: T cells mature in a gland called the thymus, which sits just in front of and above the heart. As people age, the tissue in their thymus shrinks and is replaced by fatty tissue, resulting in reduced production of immune cells. This process is accelerated by lifestyle factors like poor diet and low exercise, which are both associated with stress.]

Immune aging is associated not only with disease, but also hastens organ system aging and reduces the receptivity and efficacy of vaccines.

USC researchers sought to find how much of immune aging was influenced by social stress: they queried and cross-referenced enormous data sets from a national longitudinal study of economic, health, marital, family status, and public and private support systems of older Americans (University of Michigan’s Health and Retirement Study).

In addition, USC researchers analysed questionnaire responses from a national sample of 5,744 adults over the age of 50. The questionnaire was designed to assess respondents’ experiences with stressful life events, chronic stress, everyday discrimination, and lifetime discrimination. Flow cytometry was used to analyse the participants’ blood samples to gauge immune activity.

As expected, people with higher stress scores had “older” 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 T cells remained strong even after controlling for education, smoking, drinking, weight (BMI), and race or ethnicity.

“In this study, after statistically controlling for poor diet and low exercise, the connection between stress and accelerated immune aging wasn’t as strong,” said Eric Klopack, a postdoctoral scholar in the USC Leonard Davis School of Gerontology. “What this means is people who experience more stress tend to have poorer diet and exercise habits, partly explaining why they have more accelerated immune aging.”

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

USC researchers also highlight a common virus that is known to have a strong effect on accelerating immune aging. Cytomegalovirus (CMV) is an asymptomatic virus in humans. CMV is dormant most of the time but can flare up, especially when a person is experiencing high stress – CMV vaccination could be a simple and potentially powerful intervention that could reduce the immune aging effects of stress.

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Category: Features, Health alert

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