A recent study published in the journal Proceedings of the National Academy of Science (PNAS) has found that social stress can speed up immune system aging. As we age, our immune system naturally begins to decline. This aging process, called immunosenescence, is believed to play an important role in many age-related health conditions like cancer and cardiovascular disease and is also believed to be responsible for older people’s less effective response to vaccines. While immune system aging is a normal, expected part of aging, external factors like stress are now believed to accelerate this process.
Stress and Your Immune System
To better understand why people with the same chronological age can have different immune system ages, Eric Klopack, Postdoctoral Researcher in Gerontology at the University of Southern California, and his colleagues examined data from the Health and Retirement Study (HRS), a large, nationally representative survey of U.S. adults over age 50.
HRS researchers asked participants about different stressors they have experienced during their life. These stressors include stressful life events such as job loss; discrimination, such as being treated unfairly or being denied care; major lifetime trauma, such as a family member’s having a life-threatening illness; and chronic stress, such as financial strain.
Recently, HRS researchers, according to Klopack, have also started collecting blood samples from some of the study’s participants. After collecting these samples, HRS researchers began counting the number of different types of immune cells present, including white blood cells. Immune system cells, like white blood cells, play a vital role in immune responses to viruses, bacteria, and other foreign bodies.
“This is the first time such detailed information about immune cells has been collected in a large national survey,” said Klopack.
By analyzing data from nearly 6,000 HRS study participants, all of which provided blood samples and answers to survey questions about stress, Klopack and his colleagues found that people who experienced more stress had lower levels of ‘naive’ T cells, which Klopack describes as “fresh cells needed to take on new invaders the immune system hasn’t encountered before.”
The team also found that participants with higher levels of stress also had a larger proportion of ‘late differentiated’ T cells, which are older cells that have lost their ability to fight invaders and, as a result, produce proteins that can increase harmful inflammation. People with low proportions of newer T cells and high proportions of older T cells have a more aged immune system.
“After we controlled for poor diet and low exercise, however, the connection between stress and accelerated immune aging wasn’t as strong. This suggests that improving these health behaviors might help offset the hazards associated with stress,” said Klopack.
Furthermore, Klopack and his team found that after they had accounted for potential exposure to cytomegalovirus, a common, typically asymptomatic virus associated with immune system aging, the link between stress and immune system aging was reduced.
Understanding Immune System Aging
The link between stress and immune system aging may not come as a surprise to many. Stress has been linked to several major health conditions, such as heart disease, depression, obesity, and gastrointestinal problems like gastroesophageal reflux disease (GERD). However, studies such as this confirm that by reducing your stress levels, you can make a major impact on your quality of life.
“Our study helps clarify the association between social stress and faster immune aging. It also highlights potential ways to slow down immune aging, such as changing how people cope with stress and improving lifestyle behaviors like diet, smoking, and exercise,” said Klopack in regards to the team’s findings.
It’s important to note, however, that epidemiological studies, such as this, cannot completely establish cause and effect. More research is needed to confirm whether reducing stress or making lifestyle changes can slow immune system aging. Klopack also notes that future studies are needed to better understand how stress and latent pathogens like cytomegalovirus interact to cause illness 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.”
Put simply, a less aged immune system is better equipped to fight infections and generate protective immunity from vaccines. Immunosenescence may help explain why certain people are more likely to have more severe cases of COVID-19 and have weaker responses to vaccines as they age. Immune system aging is a normal part of life, however, understanding what influences or accelerates this process may help future researchers better address age-related disparities in health and illness.
Did You Know That Social Stress Speeds Up Immune Aging?
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