Stress ages the immune system.

Psychosocial stress, such as that experienced with discrimination or trauma, has profound effects on the human body. For example, evidence suggests that stress alters the immune system, driving inflammatory processes and impairing antiviral responses. Findings from a recent study demonstrate that stress accelerates immune aging.

Immune function wanes as the body ages, a phenomenon referred to as immunosenescence. This gradual deterioration of the immune system is widely considered the primary driver of the increased rate of infections and cancers in older adults. Multiple factors promote immunosenescence, including genetics, nutrition, exercise, and pathogen exposures, among others.

The investigators analyzed blood samples taken from more than 5,700 participants over the age of 50 years who were enrolled in the Health and Retirement Study, an ongoing study of older adults living in the United States. They measured the types and characteristics of the participants' immune cells, including CD4+ naïve (immature) cells, CD4+ differentiated (mature) cells, CD8+ naïve cells, and CD8+ differentiated cells, as well as the ratio of CD4+ to CD8+. Having more immature cells is indicative of a younger immune cell profile. The participants provided information about their socioeconomic status, lifestyle practices, and lifetime exposures to various stressors, including stressful life events, chronic stress, everyday discrimination, lifetime discrimination, and life trauma.

The investigators found that participants who had experienced more stress had fewer immature CD4+ cells and more mature CD4+ cells. Similarly, those who had experienced more stress had fewer immature CD8+ cells and more CD8+ cells. Those who had experienced high lifetime discrimination and chronic stress tended to have a lower CD4+ to CD8+ ratio, an indicator of impaired immune function. However, some of the harmful effects of stress were partly ameliorated by lifestyle factors, such as not smoking or drinking alcohol, and maintaining a healthy weight.

These findings suggest that psychosocial stress accelerates immune aging, potentially driving disease and premature death in vulnerable groups. However, lifestyle practices may moderate this risk. Interestingly, evidence suggests that a fasting-mimicking diet promotes the return of a more youthful immune cell profile. Learn more in this clip featuring Dr. Valter Longo.

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