People who felt stressed, anxious, lonely, depressed or worried about Covid before getting infected were at higher risk of developing long-term symptoms from their illness, a new study found.
For the research, published Wednesday in the journal JAMA Psychiatry, a team at Harvard looked at survey responses from nearly 55,000 people in the United States and Canada from April 2020 to November 2021.
Of that group, more than 3,000 participants said they'd had Covid, and around 1,400 said they had long Covid, defined as Covid-related symptoms lasting four weeks or longer.
The results showed that people who reported psychological distress before they got infected had a 32% to 46% increased risk of long Covid, compared to people who did not report such distress. And those who reported high levels of two or more types of psychological distress, such as both depression and anxiety, had a 50% increased risk.
What's more, the study found a stronger association between long Covid and psychological distress than long Covid and some of its known physical risk factors, such as obesity, asthma and hypertension.
“The factors that we identified are more strongly associated with risk of long Covid than pretty much anything else anyone’s found," said Andrea Roberts, an author of the study and a senior research scientist at the Harvard T.H. Chan School of Public Health.
The findings indicate that mental health can have an effect on physical Covid symptoms, the researchers said. But they emphasized that the long Covid symptoms among the patients studied were very real and arose as a result of their infection.
“The results shouldn’t be misinterpreted as supporting post-Covid conditions as psychosomatic,” said Jacqueline Becker, a clinical neuropsychologist at the Icahn School of Medicine at Mount Sinai, who wasn’t involved in the research.
Why there's a link between distress and long Covid
The new study comes with a few limitations. First, many of the people surveyed were employed as health care workers during the early months of the pandemic, so their stress levels might have been higher than that of the general public. If so, the study results could inflate the role of stress in developing long Covid. Second, participants self-reported their Covid cases, since testing wasn’t widely available at the beginning of the study.
But the researchers were careful to address a third potential critique, which is that some long Covid symptoms overlap with symptoms of psychological distress, making it difficult to pinpoint their cause.
The Harvard team separated the overlapping symptoms, such as fatigue, brain fog and memory issues, to look at just symptoms such as a persistent cough, shortness of breath or trouble smelling or tasting, which are not usually linked to psychological conditions.
The results were “almost identical,” Siwen Wang, one of the study’s authors, said.
Wang and her team suspect that a few factors could link stress and long Covid: First, stress can activate molecules that signal the body to produce inflammation. Stress can also lead to a suppressed immune response, making it harder for the body to fight off viruses. She said people with depression might even develop antibodies that mistakenly target their own cells.
“Having a mental health issue is always going to be more likely to predispose you to health problems later on, whether it’s Covid, long Covid [or] a different post-viral illness,” Becker said.
Of U.S. adults overall, around 19% of those who've contracted Covid have long Covid symptoms, according to a June study from the Centers for Disease Control and Prevention. For some, the symptoms are debilitating. In the new study, 800 people surveyed said their long Covid was preventing them from engaging in routine daily activities.
“We’re seeing people who are just having trouble leaving the house or performing other, more regular activities like remembering to turn off the stove when they’re cooking. Multitasking has become a little bit more effortful. Some people aren’t able to function at all,” Becker said.
The Harvard researchers don't yet know whether reducing stress could lower a person's risk of long Covid, or if mental health care could serve as a long Covid treatment. But they're important questions to answer, Roberts said.
“If you already have long Covid, if you make sure that you have low levels of stress and are well-treated, will that possibly help you recover faster?” she said. “We don’t know. But that’s definitely where people should be looking now.”
Regardless of any ramifications for those living with or at risk of long Covid, Becker said, “stress reduction is never harmful — it can always be helpful."