Study Finds Stress Accelerates Immune Aging, Increases Risk of Cancer and Infection

A study found that experiencing stress in the form of trauma, chronic stress, acute stress, and discrimination accelerated the aging of the immune system, leading to a weakened immune system that is more prone to infections and at a greater risk of developing cancer and other diseases.The researchers found that stress such as chronic stress, acute stress, trauma, and discrimination accelerated the aging of the immune system. This was demonstrated through the accelerated depletion of naïve or immature T cells and increased terminally differentiated or mature T cells. Lifetime trauma and discrimination were associated with accelerated depletion across the two major types of T cells—those that mount an immune attack and those that regulate immune attack. Whereas chronic stress, acute stress event, and stress from everyday discrimination were associated with aging of only one type. However, the study found that the association between stress and accelerated aging became weak when lifestyle factors such as smoking, obesity, alcohol, and age were removed. This indicated that individuals who experience stress “tend to have poorer diet and exercise habits,” said the lead study author Dr. Eric Klopack from the University of California. The authors suggested improved diets and exercise, implying that the response to stress events determines an individual’s health. Additionally, researchers found cytomegalovirus (CMV), a virus of the herpes family, to also be a factor in immune aging for many participants. CMV is a common virus known to have a strong effect on accelerating immune aging. Once infected, the person will have the virus for life, often in the form of shingles or cold sores. Though the virus usually remains latent and asymptomatic, it can flare up, especially when a person is experiencing high stress. As part of the study, 5,744 Americans in retirement were surveyed; the average age of participants was 68.9 years at the time of the study. Participants’ racial demographics were selected to represent the population, with the majority of the recruits within the non-Hispanic white racial groups. Blood samples were taken, and their T cells were counted. Though T cells are not the only cells in the immune system affected by immune aging, they are a critical component of the immune system. T cells are particularly important in fighting off cancers and pathogens. Thus, early loss of T cells can be a major risk factor for cancers, infectious diseases, and other conditions. Contrary to the many immune cells that attack all pathogens and cancer the same way, T cells can recognize different pathogens, allowing for a specific immune defense that is better at controlling infections. Naïve T cells are immature and need to encounter a pathogen or cancer cell to maturate into differentiated cells that can mount specified attacks. During the maturation process, they will divide and proliferate, producing more cells in the immune system. These cells have unlocked potential that normally should only be released upon encountering a danger to the immune system. However, in accelerated immune aging, the naïve cells decline at a faster rate to become terminally differentiated cells that are in the last stage of a T cell’s life. Though naïve T cells start to be depleted from puberty onwards, the accelerated loss of immune cells puts a person at a greater risk of cancers and diseases, with researchers speculating that a person experiencing the greatest stress may not live to old age. The study highlights the impact of social stress on immune aging, “highlighting a key role for healthy behaviors and social-environmental conditions” on T cell health and decline. Previous studies have also associated stress with impaired immune system function, reinforcing the findings of this study. To improve accelerated aging, the authors suggested interventions aimed at “increasing resilience” or reducing stress events.