Could stress be another preexisting condition that makes Covid-19 infections worse?
Many Americans are understandably feeling anxious about this cascade of events — on top of any stressors they may have already been dealing with. “The technical term is, ‘It’s a lot,’” says Linda Goler Blount, president and CEO of the Black Women’s Health Imperative.
A Centers for Disease Control and Prevention survey of 5,412 people in late June found that 31 percent were experiencing symptoms of anxiety and depression, about three times the number of respondents who said the same in the first two quarters of 2019. Another 26 percent reported symptoms of a trauma- or stressor-related disorder. Eleven percent of people said they had seriously considered suicide in the previous 30 days.
Now some researchers are asking if stress — especially chronic stress — might be another preexisting condition that makes Covid-19 infections worse.
Our bodies have evolved to respond in the moment to stressful situtions, both physical and emotional. This is often called the “fight-or-flight” response, and it helps us react quickly to danger. But when this becomes a long-term response, these involuntary reactions can be harmful.
There isn’t a single agreed-upon definition of what “chronic” means, though some researchers think stress that persists for weeks or months likely qualifies. Generally, “People thinking about something consistently over time qualifies as a chronic stressor,” says Paula Braveman, director of the Center on Social Disparities in Health at the University of California San Francisco.
Other researchers say an important feature of chronic stress is its instability, of not knowing whether or when the stressor will end. (The pandemic seems to fit the bill.) Still others define it as the body’s inability to return to base level amounts of important hormones, often developing a new, elevated “normal” for stress hormones such as cortisol.
Cortisol is an important part of the stress response, and new research suggests cortisol levels appear to impact the severity of Covid-19. There’s still a lot we don’t understand about the relationship between the two, but clinical trials of a Covid-19 treatment using dexamethasone — a drug that reduces the body’s natural cortisol production, as well as inflammation — has been found to help critically ill patients.
“High levels of cortisol are associated with poor [Covid-19] outcomes, and drugs that block the hormone seem to improve outcomes,” says Kavita Vedhara, a University of Nottingham professor of health psychology who is conducting an ongoing study on Covid-19 and stress. Vedhara says that while further research is needed, she wouldn’t be surprised if chronic stress was found to be a risk factor for a severe case of Covid-19. “It fits with what we know about psychological stress generally, and in particular the evidence on stress and other viral infections,” she added.
Understanding how stress impacts Covid-19 could hold clues for preventing or reducing the severity of infections, as well as responding to the inequities that put some racial and minorities groups at greater risk.
Can chronic stress make us more susceptible to infection — and more severe infection?
Fifty years of research on stress suggests it has a profound effect on the body, influencing everything from memory to the way the body stores fat. It’s even been found to cause structural changes in the brain.
In general, “Chronic stress wears the body down,” says Kathryn Freeman Anderson, a sociology professor at the University of Houston. Over time, stress keeps the body locked into a heightened response, resulting in damage somewhat similar to an engine idling for too long.
Chronic stress can also make vaccines less effective. One study compared the vaccine responses of 32 caregivers of a spouse with dementia — a role associated with chronic stress — against 32 subjects in a control group. After vaccinating both groups against influenza, the researchers found that the caregivers’ stress was associated with a lowered antibody response, meaning less protection against the flu.
Conversely, in 2018, Vedhara designed an experiment for 138 older adults to see whether a positive mood could have a protective effect. For two weeks before and four weeks after their annual flu shot, participants self-reported how they felt using a diary. Vedhara found that psychological influences, including stress and mood, influenced participants’ antibody response. (Stress responses are often measured by observing specific emotional states.)
Vedhara found that if participants felt unstressed and upbeat, particularly on the day they were vaccinated, the vaccine worked better. The effect on antibody production was about as large as the effect of statins on cardiovascular events. “These are very tangible, very profound effects,” Vedhara says.