Study: Long COVID ‘brain fog’ linked to inflammation, stress markers

A new study indicates the debilitating “brain fog” suffered by millions of long COVID patients is linked to changes in the brain, including inflammation and an impaired ability to rewire itself following COVID-19 infection.

United Press International reported this week that the small-scale study, conducted by researchers at Corewell Health in Grand Rapids, Michigan, and Michigan State University, shows that altered levels of a pair of key brain chemicals could be the culprit.

The study marks the first time doctors have been able to provide scientific proof that validates the experiences of the approximately 12 million COVID “long-haulers” in the U.S. who have reported neurological symptoms.

Researchers looked at biomarkers in study participants and found that those complaining of brain fog had higher levels of an anti-inflammatory protein that is crucial to regulating a person’s immune system, UPI reported. They also showed lower serum levels of nerve growth factor, a protein vital to the brain’s plasticity.

The study examined 17 COVID-19 patients, including 10 who still experienced symptoms six months after contracting the virus. The most debilitating symptom is brain fog, described by Yale Medicine as “sluggish” thinking, forgetfulness, difficulty processing information and an inability to focus or concentrate on tasks they used to complete with ease.

The National Library of Medicine describes plasticity as the ability of the brain to change its activity in response to illness or injury. That healing process includes reorganizing the brain’s structure, functions or connections.

One of the biggest issues involving long COVID has been doctors’ inability to find physical proof of the symptoms described by patients. The study has changed that, according to co-author Dr. Bengt Arnetz.

“We found biological changes, which I think [is a] very big strength for this study,” Arnetz said, according to UPI. “In parallel with the effects on executive function, we also saw that [NGF], which reflects the brain’s ability to adapt to grow new neurons and connection, was suppressed in long COVID. This is aligned with the findings in the neuro-cognitive test.”

For the neuro-cognitive test, researchers put study participants through a battery of psychological exams. The results were unremarkable for all the exams except one — the “letter fluency” test.

Arnetz’s co-author, clinical neuropsychologist Michael Lawrence, explained that a fluency test measures a person’s executive functioning under time constraints. It requires a patient to generate words beginning with a specified letter of the alphabet or to name items from a specific category, like animals or fruit.

Errors or difficulty performing the task are indicative of executive functioning impairments as well as impairments in memory and language. According to the Library of Medicine, similar impairments are found in conditions like Alzheimer’s disease, vascular dementia and Lewy body dementia.

Lawrence said he believes the study is helpful because “now we have some objective findings that really confirm what patients are describing and feeling.”

Identifying long COVID sufferers through the identified biomarkers could help the medical community develop multidisciplinary treatment for their symptoms, he said.

“I think patients and our medical community, at least years ago, tended to separate the mental health from the physical. But what we know is they’re all very interconnected,” Lawrence said. “The more we can improve mental health-related symptoms, what we see is decreased reports of pain and fatigue. We really need to treat the whole person, but we need to treat it early.”