You have your job, there may be children, friends, hobbies and possibly also the care for a loved one, in short, we are almost all busy. But when busyness turns into stress, something goes wrong.

According to new research from the University of Southern California (USC), stress accelerates the aging of immune cells and may increase the risk of cancer, cardiovascular disease and infections caused by COVID-19.

The research published last week in PNAS may help explain why some people stay healthy into old age and others don’t. “Age-related changes in the immune system play a critical role in deteriorating health,” said study leader Eric Klopack of the USC Leonard Davis School of Gerontology. “This study helps to elucidate the mechanisms behind accelerated aging of immune cells.”

Worn white blood cells

As people age, the immune system deteriorates. Too many worn-out white blood cells keep circulating and too few fresh new ones arrive to attack hostile invaders. Aging of the immune system is not only associated with cancer, but also with cardiovascular disease, an increased risk of pneumonia, reduced effectiveness of vaccines and the aging of organs.

But what is driving the large health differences between adults of the same age? The USC researchers have attempted to link long-term exposure to stress—a known cause of ill health—and the weakened immune system.

To do this, the researchers plowed through a massive dataset from a longitudinal study of older Americans’ finances, family, health and support. To calculate exposure to various forms of stress—chronic stress, discrimination, stressful events—the researchers analyzed the responses of more than 5,700 U.S. people over 50 in a survey designed specifically to measure stress. In addition, they took blood samples from the participants.

Due to stress you not only have little time to prepare healthy food, you also have more appetite for sweets and snacks. Photo: Elnur

As expected, the people with a higher stress score also had an ‘older’ immune profile with fewer fresh white blood cells and more worn-out ones. The association between stressful events and a decrease in fresh immune cells remained strong, even after adjusting for education level, smoking, drinking, BMI and ethnicity.

lifestyle

But that was not the case for all forms of stress. T cells, a crucial part of immunity, mature in the thymus gland, which sits near the heart. As people age, the tissue around the thymus shrinks. This is replaced by adipose tissue, which leads to a reduced production of immune cells. Previous research indicates that this process is accelerated by lifestyle factors such as a poor diet and little exercise. This is again linked to stress.

“Our study shows that unhealthy behaviors, such as smoking, drinking, eating poorly and exercising little, play a role in the link between stress and the accelerated aging of immune cells,” said study researcher Eric Klopack. Scientias.nl. “There is an opportunity for intervention there. But further research is needed to find out exactly to what extent this behavior influences.”

However, it seems clear that there is a link. “After adjusting for poor diet and physical activity, the association between stress and accelerated immune age aging was not as strong,” Klopack says. “What this means is that people who experience more stress tend to have worse lifestyle habits, which partly explains why their immune systems age so quickly.”

Stress and food

Much research has been done on the relationship between stress and food. Harvard Medical School writes that a stress peak initially reduces hunger to give your body room to deal with the situation. If the stress persists, the cortisol that your body produces in abundance will actually make you more hungry. This hormone also stimulates motivation, including the motivation to eat. Under the influence of insulin and possibly the hunger hormone ghrelin, you also feel like eating unhealthy sugary and fatty foods.

Improved exercise and diet may therefore help to counteract stress-induced immune system aging in older adults, the researchers said. They also mention vaccination against the cytomegalovirus (CMV) as a way to strengthen the immune system. CMV is a herpes virus that is present in the body most of the time in many people without symptoms. This virus is known to have a strong effect on the accelerated aging of immune cells. Complaints can also arise when there is a lot of stress. The researchers corrected for the virus and again found that the connection between stress and immune age decreased as a result.

In fact, according to Klopack, it was the most surprising finding. “Our results are consistent with previous research. We show that part of the reason stress is associated with the aging of immune cells is that stress activates the CMV virus. The virus may deplete new T cells, leading to an increase in the number of worn-out T cells,” said Klopack. “We found a strong link between a CMV infection and the aging of the immune system. This virus receives little attention from the general public or from researchers.” There is still a task for doctors and scientists.

This study provides numerous guidelines for combating immune cell aging: through a better lifestyle, a vaccination against CMV or through less stress in general. “Interventions to reduce or better manage stress can help reduce the aging of the immune system and thus reduce health disparities between the elderly,” concludes Klopack.