Long Covid is one of the most enduring mysteries of the pandemic. In particular, who is most at risk of developing the range of post-Covid conditions collectively called long Covid has remained opaque.
A study published last week in the journal JAMA Psychiatry may shed some light on long Covid risk factors. Researchers in Boston determined that patients experiencing psychological stress like depression, anxiety, and loneliness before contracting Covid were more likely to develop long Covid than those who weren’t.
The results could help us better understand the condition that is currently affecting millions of Americans.
“Despite the high prevalence and daily life impairment associated with long Covid, long Covid is still poorly understood, and few risk factors have been established,” Siwen Wang, a research fellow at Harvard T.H. Chan School of Medicine and one of the authors on the study, tells Inverse.
What they did— The researchers conducted a prospective cohort study — an observational study in which researchers follow two or more groups of similar participants over time. In this case, three cohorts of primarily female participants were followed from April 2020 to November 2021 using seven periodic surveys.
These cohorts were already established and involved in ongoing longitudinal studies: Nurses' Health Study II, Nurses' Health Study 3, and the Growing Up Today Study.
“We did not purposefully choose to enroll new study participants, as those were active participants from our ongoing cohorts that were established decades ago. We knew these people responded well and were dedicated to scientific research,” Wang says.
Among the 54,960 participants, the average age was 57.5 years and 96.5 percent were white. 38 percent were active healthcare workers.
At the beginning of the pandemic, all survey respondents were asked to self-assess how worried they were about Covid-19, as well as how often they experienced symptoms of depression, anxiety, loneliness, or stress.
What they found— Researchers found that participants with psychological distress before Covid-19 infection, including depression, anxiety, worry, perceived stress, and loneliness, were associated with a 32 to 46 percent increased risk of long Covid.
“This risk was not explained by health behaviors, such as smoking, or by physical health conditions, like asthma,” Wang says. “And participants with two or more types of distress prior to infection were at nearly 50 percent increased risk for long Covid.”
Patients with higher psychological distress prior to getting Covid also had more symptoms of long Covid and were up to 50 percent more likely to have “daily life impairment due to long Covid,” Wang adds.
Wang and her colleagues were surprised by how strongly psychological distress before Covid was associated with an increased risk of long Covid.
“Distress was more strongly associated than physical health risk factors such as obesity, asthma, and hypertension,” she says.
Digging into the details— Wang stresses that the researchers aren’t suggesting that long Covid is in any way psychosomatic.
“We pointed out in the paper that there are multiple reasons to support that long Covid is NOT 'just in our head'. Among people who developed long Covid, still nearly half were not depressed before infection,” she says. “More importantly, when we excluded people who only reported psychological, cognitive, and neurological symptoms [i.e., potential symptoms of mental illness] from the analysis, the results were the same.”
Further, it’s not unprecedented for mental health conditions to affect infections and other types of illness.
“We know that mental health conditions are associated with greater severity and longer duration of acute respiratory tract infections, such as flu or the common cold,” Wang says. “Depression and other mental illness have been associated with greater risk of more severe Covid-19, including risk of hospitalization.”
Wang says the research into psychological distress preceding infection as a risk for post-infection syndromes is limited but, “we think it is where future research should be looking at - whether managing psychological distress will prevent or improve post-infection syndromes.”
One major limitation of the study is the heterogeneity of the participants, which were predominately white and female, with a large proportion being active healthcare workers.
“Their experience during the pandemic may not be the same as another random population,” Wang says. “Therefore, more studies are needed to replicate our findings.”
Still, the results point to the very real need to consider psychological health in addition to physical health as a risk factor for developing Long Covid.
Wang notes that the World Health Organization reports that 75 percent of people in low and middle-income countries receive no treatment for mental disorders. Still, more do not receive adequate treatment for these conditions.
“We need to increase public awareness of the importance of mental health and focus on getting mental health care for people who need it, increasing the supply of mental health clinicians and improving access to care,” she says.