To investigate how social stress affects immune cells, the research team asked 5,744 adults over the age of 50 about a wide range of stressful life events and examined their blood samples. People who were more stressed had a higher percentage of depleted white blood cells and fewer fresh cells – so their immune profile was biologically older. This link remained visible, taking into account various influencing factors such as level of education, smoking, alcohol or BMI.
The study also found that people who are more stressed tend to have worse eating and exercise habits. “That partly explains why they have faster immune aging,” Dr. Eric Klopack of the University of Southern California. Thus, improving diet and exercise in older adults may have the potential to offset the stress-related aging of the immune system.
The aging of the immune system is a long-recognized effect known to experts as immune senescence: as we age, more worn white blood cells circulate in the blood, while the number of “naive” white blood cells that can receive new invaders decreases. Immune aging is associated with cancer, cardiovascular disease, pneumonia, reduced vaccine efficacy and aging of organ systems.
Co: DOI 10.1073 / pnas.2202780119