• Posted June 14, 2022

Stress Can Age, Weaken Your Immune System

Stress may take a huge toll on your health, weakening your immune system and opening the door to serious illness, a new study suggests.

Traumatic events, job strain, daily stressors and discrimination may all speed aging of the immune system, increasing the risk for cancer, heart disease and other illness, including COVID-19, researchers report.

"New T-cells are needed to respond to novel infections like COVID-19 and for vaccine efficacy. ... Immune aging may help explain why older people are more likely to have more severe COVID-19 cases and tend to have weaker responses to vaccines," said lead researcher Eric Klopack, a postdoctoral scholar at the Leonard Davis School of Gerontology at the University of Southern California, Los Angeles.

Smoking and drinking alcohol, risky lifestyle habits that are often a response to stress, can also weaken an immune system, he added.

"These health behaviors might help explain the link between stress and immune aging," Klopack said. "People who experience more stress may be more likely to engage in risky health behaviors. These behaviors may reduce the production of new naive cells."

The good news is that not drinking or smoking might help offset some of the immune aging associated with stress, he said.

But even with lifestyle changes, the immune system naturally begins to weaken as people age, a condition called immunosenescence. In old age, the immune system includes many worn-out white blood cells and only a few new white blood cells that can fight infection. A weakened immune system is linked with cancer, heart disease and the risk of infectious diseases, such as pneumonia.

Another possible explanation for weakening of the immune system involves cytomegalovirus (CMV) infection, Klopack said.

"CMV is a common infection that has been shown to have large effects on the immune system," he explained. "To keep CMV in check, the immune system has to commit a large amount of resources to CMV, meaning a lot of T-cells are produced to handle CMV, some of which will remain as aged nonfunctioning cells."

Research has suggested that social stress can trigger the activation of CMV, forcing the immune system to commit more resources in response.

"In our study, controlling for CMV also reduced the associations between stress and the health of T-cells. So, one pathway may be that chronic stress causes regular reactivation of CMV, leading to a more aged immune system," Klopack said. "So, developing an effective CMV vaccine could help alleviate immune system aging."

To find out the role stress plays in weakening the immune system, the researchers analyzed responses from more than 5,700 people over the age of 50. The participants completed a questionnaire that assessed experiences with social stress, including stressful life events, chronic stress, everyday discrimination and lifetime discrimination.

The participants also provided blood samples that were analyzed with a technique called flow cytometry, which counts and classifies blood cells as they pass in front of a laser.

Klopack's team found that people with higher stress scores had seemingly older immune systems, with fewer new disease-fighting T-cells and more worn-out white blood cells. The association remained even after taking into account education, smoking, drinking, weight and race or ethnicity.

The report was published June 13 in the Proceedings of the National Academy of Sciences.

Dr. David Katz is a specialist in preventive and lifestyle medicine and president of the True Health Initiative in Tulsa, Okla.

"Stress has long been recognized as a potent factor influencing health, but measuring stress itself and capturing its effects objectively has been a challenge," said Katz, who was not part of the research.

This study provides a vivid and novel window on the consequences by examining the biological age of the immune system, Katz said. "Stated simply, more unmanaged life stress means accelerated aging of the immune system," he noted.

This has clear implications during a pandemic, Katz said.

"Variations in the toll of COVID infection vary, ultimately, with variations in immune system vitality," he said. "It has general significance for a population always concerned with the pace of aging. As goes any system as vital as immunity, so goes the whole person."

More information

For more on stress and health, see the American Psychological Association.

SOURCES: Eric Klopack, PhD, postdoctoral scholar, Leonard Davis School of Gerontology, University of Southern California, Los Angeles; David Katz, MD, MPH, specialist, preventive and lifestyle medicine, and president, True Health Initiative, Tulsa, Okla.; Proceedings of the National Academy of Sciences, June 13, 2022