It is already well established that high levels of stress for a prolonged period of time can lead to health problems. A recent study has now found that stress has other negative effects, including the ability to age the immune system.
Eric Klopack, postdoctoral researcher of gerontology at the University of Southern California, lead the study to find the correlation between stress and aging of the immune system. The team of researchers analyzed survey responses from more than 5,700 adults over the age of 50 in the United States. The respondents were asked about their experiences with social stress in their everyday lives. They also studied blood samples from the respondents in order to measure the levels of T-cells found in their blood.
It was found that there is a strong relationship between high-stress levels and high proportions of older T cells. The presence of fewer naive T cells with respect to older T cells in stressed adults has led to more aged immune systems. Since Naive T cells have not yet interacted with an antigen, they are important for fighting off diseases and viruses that the body hasn’t encountered before. Klopack states that “New T-cells are needed to respond to novel infections like COVID-19 and for vaccine efficacy. However, the older terminally differentiated T cells have already served their purpose and can no longer help direct immune responses. They may, in fact, instead produce proteins that can increase harmful inflammation in the body.
Klopak stated that “ideally, you want to have a large, diverse group of these naive T-cells so that they can be ready to respond to new threats you haven’t encountered before, including novel threats like COVID-19, as well as new vaccines”. While people naturally tend to have fewer naive cells as they get older, social stress can speed up this process.
After controlling for factors such as education, weight, smoking, and drinking habits, it was found that the relationship between stress and T cell proportion was reduced. According to Klopack, there are factors other than stress that can affect the age of one’s immune system both positively and negatively. Engaging in regular exercise and healthy eating habits while avoiding drinking and smoking may, in fact, help slow immune aging.
An aged immune system can leave people more susceptible to cancer and heart disease while also leading to weaker responses to vaccines.