As we age, the immune system begins to naturally degrade—a process known as immunosenescence referred to as. This increases the susceptibility to viruses and bacteria and thus to diseases: from colds and flu to pneumonia, cancer and cardiovascular diseases. And vaccines are also less effective when the immune system is weakened.
How early this aging process begins varies from person to person. A research team investigated whether the social stress that someone was and is exposed to over the course of life accelerates immune aging Eric Klopack from the University of Southern California Department of Gerontology. The results were now im Fachjournal „Proceedings of the National Academy of Sciences“ (PNAS) published.
Questionnaires, data sets, blood samples
In a US-wide sample of 5,744 people over the age of 50, the researchers analyzed possible connections between signs of immune aging and various causes of social stress. This can be caused, among other things, by traumatizing life events, by professional stress – from strong pressure to bullying to unemployment – and also by lifelong discrimination and social disadvantage.
In a questionnaire, the subjects answered questions that were aimed at the social stress they had experienced. The research team combined the results with datasets from the extensive Health and Retirement Studie from the University of Michigan, a national longitudinal study of the health and retirement of Americans that has been running since 1990. Blood samples from the participants were also analyzed.
Social stress affects T cells
The research found that individuals with higher levels of stress have a weaker immune profile. This provides information about the type and number of existing immune cells and their activation status. As the immune system ages, the percentage of worn-out white blood cells increases. At the same time, the number of those white blood cells that are important for the defense reaction against pathogens such as viruses and bacteria decreases: the T-lymphocytes, in short T cells.
The link between social stress and less responsive T cells is also consistent after accounting for other influencing criteria such as educational level, Body-Mass-Index (BMI) and increased cigarette and alcohol consumption remained strong, according to the study authors.
“Causes cannot always be eliminated”
With the study, the authors want to contribute to better research into health in old age – in order to be able to subsequently develop targeted measures to prevent immune aging. At least in part, the research should also provide clues as to why some older people become more ill with Covid-19 than others after being infected with the coronavirus.
“As the world population continues to age, there is a need to understand disparities in the health of older people,” says lead author Klopack. Because: “Age-related changes in the immune system play a decisive role in the deterioration of health”. The study helps to elucidate mechanisms involved in accelerated immune aging.
And while many of the causes of social stress are often difficult to address at an individual level, the researchers say the study’s findings suggest that differences in immune aging can be mitigated by interventions designed to reduce stress or reduce stress increase resilience could be decreased.