Stress Ages the Immune System: Study

Findings suggest ways to counter chronic stress, preserve attack-ready immune cells

We lose healthy immune cells over the course of our lives, especially if we are often stressed, eat poorly, and don't exercise. (4 PM production/Shutterstock)

We’ve all heard that too much stress can hurt our health. Stress contributes to ailments such as high blood pressure, heart disease, and diabetes.

Now, a study published on June 13 in Proceedings of the National Academy of Sciences (PNAS), shows that years of accumulated stress can more rapidly age the immune system. This finding could help explain disparities in health outcomes among people of the same chronological age, and provide insight to help those affected by stress.

The immune system degrades with age and worn-out white blood cells proliferate while “naive” new cells that are ready to fight harmful invaders decrease. This normal process of immune system aging is called immunosenescence. But the rate at which this deterioration occurs varies widely among people of the same chronological age.

Researchers from the University of Southern California (USC) analyzed responses from a national sample of 5,744 adults over the age of 50 who were asked about their experiences with five specific types of social stress: stressful life events, chronic stress, everyday discrimination, lifetime discrimination, and life trauma. They then tested participants’ blood samples using a process called flow cytometry, in which blood cells pass single file in front of a laser that counts and classifies the cells.

The researchers found stressful life events were associated with an increase in markers of immune system aging. People who experienced more life stress had fewer attack-ready immune cells, leaving them at higher risk of developing a host of age-related illnesses, including cancer, cardiovascular disease, and severe infections from viruses such as COVID-19.

Although this study looked at older adults, younger people may suffer the same effect. A study published in the October 2018 issue of the journal Brain, Behavior, and Immunity, found similar markers of accelerated immune system aging in high-stress mothers between the ages of 20 and 50.

Interestingly, the difference in immune system aging shrank considerably after the researchers controlled for poor diet and lack of exercise, lead study author Eric Klopack, a postdoctoral scholar at the USC Leonard Davis School of Gerontology, noted in a statement.

“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.”

Everybody experiences some amount of stress, and not all stress is harmful. Some ‘good’ stress, which psychologists refer to as ‘eustress,’ may even be beneficial. But, in general, severe or chronic stress should be well managed, Klopack said.

“I know that can be difficult or impossible, but our study suggests that one way to offset the effects of stress on immune aging is to try to avoid unhealthy behaviors like smoking and drinking and to try to get regular exercise and eat a healthy diet.”

These results give hope that these simple, readily accessible lifestyle changes may significantly delay or reduce the harmful effects of stress on the immune system in older adults.