Exposure to social stress was associated with accelerated aging of the immune system, according to an NIA-funded study recently published in PNAS. The body’s immune system changes as people age, and there’s large variability in these changes. The study, led by researchers at UCLA, investigated whether social stressors added to immune system decline.

The researchers analyzed data from more than 5,500 people enrolled in the Health and Retirement Study, a long-term, nationally representative study of Americans over age 50. The researchers measured stress by analyzing responses to questions about exposure to various types of social stress, including discrimination, trauma, and other life events, such as unemployment. They also analyzed the participants’ immune profiles — a snapshot of immune system function — by drawing blood and measuring white blood cell levels, specifically T lymphocytes (also called T cells). T cells are an essential part of the immune system and help the body fight off infection.