According to a study, stress such as discrimination, work pressure, traumatic events and everyday stressors accelerate the aging of the immune system, potentially increasing the risk of cardiovascular disease, cancer and illness from viral infections such as COVID-19.
The study could help explain age-related health disparities, such as the unequal toll of the COVID-19 pandemic, and identify potential intervention factors.
Understanding age-related health inequalities is important as the world’s population of older people increases. Age-related changes in the immune system play an important role in declining health.
The immune system naturally deteriorates significantly as a person ages, a condition known as immunosenescence. A person’s immune profile weakens with age, with the circulation of too many worn-out white blood cells and not enough fresh white blood cells available to deal with new invaders.
Aging of the immune system is linked not only to cancer, but also to aging of the organ system, an increased risk of pneumonia and cardiovascular disease.
The researchers wanted to find out the reason for extreme health differences between people of the same age. They looked for a link between lifelong exposure to stress and a decrease in the vitality of the immune system.
Huge data sets were retrieved and compared with a nationwide longitudinal study of the family status, marriage, health, economic, and private and public support systems of older individuals.
Responses from a sample of 5,744 individuals over the age of 50 were examined to calculate different types of exposure to social stress. The participants answered a questionnaire designed to assess their social stress experiences, such as lifelong discrimination, daily discrimination, chronic stress, and stressful life events.
The individuals’ blood samples were then analyzed using a lab technique known as flow cytometry, which is used to count and classify blood cells as they pass one at a time in a narrow stream in front of a laser.
Individuals with higher stress scores, as expected, had older-appearing immune profiles, with lower levels of fresh disease-fighting agents and higher worn-out white blood cells. The association between stressful life events and less available T cells persisted even after controlling for BMI, drinking, smoking, education, and ethnicity or race.
Some causes of stress may be uncontrollable, but the researchers say there may be a solution.
A crucial immune component known as T cells matures in the thymus gland, which is located just above and in front of the heart. Thymic tissue shrinks as a person ages and fatty tissue replaces it, leading to a reduction in immune cell production. Previous research indicates that this process is accelerated by lifestyle factors such as reduced exercise and poor diet, both of which are linked to social stress.
The association with stress and accelerated immune system aging was not as pronounced in this study after statistically controlling for little exercise and poor diet. This means that individuals who experience more stress are more likely to have poorer exercise and less eating habits, which partly explains why their immune aging progresses more quickly. The immune aging associated with stress can be offset by improving exercise and dietary behavior.
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