Health: social stress can accelerate the aging of the immune system

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As people age, their immune system naturally begins to decline. This aging of the immune system, called immunosenescence, may play a significant role in age-related health problems such as cancer and cardiovascular disease, as well as in older people’s less effective response to vaccines.

But not all immune systems age at the same rate. In our recently published study, my colleagues and I found that social stress is associated with signs of accelerated immune system aging.

Stress and immunosenescence

To better understand why people with the same chronological age may have different immunological ages, my colleagues and I examined data from the Health and Retirement Study, a large, nationally representative survey of American adults over the age of 50 years. HRS researchers ask participants about different types of stressors they have experienced, including stressful life events, such as job loss; discrimination, such as being treated unfairly or being denied care; major trauma in life, such as a family member suffering from a life-threatening illness; and chronic stress, such as financial difficulties.

Recently, HRS researchers also began drawing blood from a sample of participants, counting the number of different types of immune cells present, including white blood cells. These cells play a central role in immune responses to viruses, bacteria and other invaders. This is the first time that such detailed information on immune cells has been collected in a large national survey.

By analyzing data from 5,744 HRS participants who both provided blood and answered stress survey questions, my research team and I found that people who experienced more stress had a lower proportion of lymphocytes. ‘Naïve’ T – fresh cells needed to confront new invaders the immune system has not encountered before. They also have a greater proportion of “lately differentiated” T cells — older cells that have exhausted their ability to fight off invaders and instead produce proteins that can increase harmful inflammation. People with low proportions of newer T cells and high proportions of older T cells have older immune systems.

However, after controlling for poor diet and low exercise, the link between stress and accelerated immune aging was not as strong. This suggests that improving these health-related behaviors could help offset the risks associated with stress.

Similarly, after accounting for potential exposure to cytomegalovirus – a common, usually asymptomatic virus known to accelerate immune aging – the link between stress and immune cell aging was reduced. While CMV normally remains dormant in the body, researchers have found that stress can cause CMV to surge and force the immune system to commit more resources to controlling the reactivated virus. Prolonged infection control can deplete stocks of naïve T cells and lead to increased depletion of T cells that circulate throughout the body and cause chronic inflammation, a major contributor to age-related disease.


Understanding Immune Aging

Our study helps clarify the association between social stress and faster immune aging. It also highlights potential ways to slow immune aging, such as changing the way people cope with stress and improving lifestyle behaviors like diet, smoking and exercise. . The development of effective vaccines against cytomegalovirus may also help to mitigate the aging of the immune system.

It is important to note, however, that epidemiological studies cannot completely establish cause and effect. Further research is needed to confirm whether stress reduction or lifestyle changes will lead to improvements in immune aging, and to better understand how stress and latent pathogens like cytomegalovirus interact to cause disease and death. We are currently using additional data from the Health and Retirement Study to examine how these and other factors like childhood adversity affect immune aging over time.

Younger immune systems are better able to fight infections and generate protective immunity against vaccines.

Immunosenescence may help explain why people are likely to have more severe cases of COVID-19 and a weaker response to vaccines as they age.

Understanding what influences immune aging can help researchers better address age-related disparities in health and disease.


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