Social Stress Has Been Linked to Accelerated Immune Aging

People's immune systems gradually deteriorate as they become older. Immunosenescence, or the aging of the immune system, may have a role in age-related health issues including cancer and cardiovascular disease, as well as older people's less effective vaccination response.

However, immune systems do not all mature at the same rate. My colleagues and I recently released a study that indicated that social stress is linked to indicators of accelerated immune system aging.

Stress and immunosenescence

My colleagues and I looked at data from the Health and Retirement Study (HRS), a large, nationally representative study of US individuals over 50, to better understand why persons of the same chronological age might have varied immunological ages.

Stressful life events, such as job loss; discrimination, such as being treated unjustly or denied care; substantial lifetime trauma, such as a family member's life-threatening illness; and chronic stress, such as financial hardship, are among the stressors that HRS researchers question participants about.

HRS researchers have recently begun taking blood samples from a group of individuals and quantifying the quantity of different types of immune cells present, including white blood cells. Immune responses to viruses, bacteria, and other invaders rely heavily on these cells. This is the first time a major nationwide study has gathered such precise information on immune cells.

My research team and I discovered that people who experienced more stress had a lower proportion of "naive" T cells – fresh cells needed to take on new invaders the immune system hasn't encountered before – by analyzing data from 5,744 HRS participants who both provided blood and answered survey questions about stress.

They also contain a higher percentage of "late differentiated" T cells, which are older cells that have lost their capacity to combat intruders and instead create proteins that might worsen inflammation. A person's immune system is more elderly if they have a low proportion of fresh T cells and a high number of older T cells.

The link between stress and accelerated immunological aging was less once we accounted for poor nutrition and lack of exercise. This shows that enhancing these health practices might help mitigate the risks of stress.

Similarly, the association between stress and immune cell aging was diminished once we accounted for probable exposure to cytomegalovirus - a common, generally asymptomatic infection known to promote immunological aging.

While CMV generally remains dormant in the body, researchers have discovered that stress can trigger it to reawaken, forcing the immune system to devote more resources to controlling the virus.

Long-term infection control can deplete naïve T cell reserves, resulting in more tired T cells that circulate throughout the body and induce chronic inflammation, which is a major contributor to age-related illness.

Understanding immune aging

Our research sheds light on the link between social stress and immunological aging. It also identifies potential approaches to reduce immunological aging, such as altering people's stress responses and improving lifestyle habits such as food, smoking, and exercise.

The development of effective cytomegalovirus vaccinations might potentially aid in the prevention of immune system aging.

It's crucial to remember, though, that epidemiological studies can't always prove cause and effect. More study is needed to determine if stress reduction or lifestyle changes enhance immunological aging, as well as to better understand how stress interacts with latent viruses like CMV to cause sickness and mortality.

We're presently examining how these and other variables, such as childhood adversity, impact immunological aging across time using more data from the Health and Retirement Study.

Immune systems that are younger are stronger at fighting illnesses and generating protective immunity from vaccinations. Immunosenescence may explain why, as people age, they are more prone to get severe COVID-19 infections and have a lower vaccination response.

Researchers may be able to better address age-related inequities in health and sickness if they can figure out what impacts immunological aging.