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Study: ‘Brain Fog’ persists among COVID-19 long-haulers

Comparing long-haul COVID-19 with chronic fatigue syndrome reveals diverging symptom patterns, find researchers at DePaul University. (iStock.com/nensuria)


CHICAGO — As people with long-haul COVID-19 continue to recover from their illness, neurocognitive symptoms may persist or even worsen over time, as reported in new findings from researchers at DePaul University. Psychologist Leonard A. Jason led the study comparing those with long-haul COVID-19 with patients who have myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

Comparing long-haul COVID-19 with another chronic illness could help researchers uncover root causes of long-term illness and inform their approach to care, Jason said. Many other symptoms of long-haul COVID-19 do appear to improve over time, which diverges from the experience of most with ME/CFS. Findings were published in the journal “Fatigue: Biomedicine, Health & Behavior” and are available at http://bit.ly/LJ_C19​.

“The symptoms hanging on most for COVID-19 long-haulers are sometimes referred to as ‘brain fog.’ People have trouble problem solving, or they get in the car and forget where they’re supposed to be going,” said Jason, director of the Center for Community Research at DePaul. Researchers defined long-haul COVID-19 as having serious, prolonged symptoms three months after contracting the SARS CoV-2 virus.

Researchers surveyed 278 long-haul COVID-19 patients about their symptoms at two points, six months apart. They also surveyed 502 ME/CFS patients about their symptoms, which have significant overlap with COVID-19. Jason and his team used the DePaul Symptom Questionnaire, a self-report measuring tool developed for use with ME/CFS patients. Researchers found:


  • At the six-month mark, COVID-19 long-haulers report worse neurocognitive symptoms than at the outset of their illness, including trouble forming words, difficulty focusing and absent-mindedness. Still, these symptoms were ranked less severe than those with ME/CFS. 
  • Most other symptoms, including sleep problems, immune-related issues, pain and gastrointestinal issues, seem to improve over time for COVID-19 long-haulers. 
  • The most severe symptom for COVID-19 long-haulers and ME/CFS patients alike was post-exertional malaise, which includes feeling physically and mentally drained or heavy.


These findings may provide other researchers with insights into nervous system pathophysiology, such as that found in patients with ME/CFS. While ME/CFS is known to have many triggers, including the Epstein-Barr virus, not every patient knows what led to their illness, noted Jason. However, COVID-19 long-haulers have a single virus to point to as the initial cause of their symptoms. Both groups face similar challenges as their family members and health care workers may not understand the changing symptom patterns.

“We don’t know how many long-haulers will stay on this type of trajectory,” Jason said. He and other researchers estimate about 10% of people who have COVID-19 become long-haulers. In reviewing the literature, the researchers found that past epidemics, including the 1918 pandemic, have also led to many patients having long-term fatigue.

“These types of serious neurocognitive complications are incredible given that millions of people have been infected,” Jason said.

DePaul Center for Community Research co-authors on the study include Mohammed Islam, Karl Conroy, Joseph Cotler, Chelsea Torres, Mady Johnson and Brianna Mabie. Funding for this research was provided by the National Institute of Neurological Disorders and Stroke (grant number 5R01NS111105).

Leonard Jason

Media Contact:
Kristin Claes Mathews

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