Brain fog, other long Covid symptoms can last over a year, study finds

The devastating neurological effects of long Covid can linger for more than a year, according to a study published on Tuesday – even if other symptoms subside.

The study, published in the journal Annals of Clinical and Translational Neurology, is the longest follow-up study of neurological symptoms in long Covid patients who have never been hospitalized with Covid.

Neurological symptoms — which include brain fog, numbness, tingling, headache, dizziness, blurred vision, tinnitus, and fatigue — are most commonly reported for the condition.

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The new study, led by researchers at Northwestern University, follows a shorter-term study published last spring that involved 100 patients with long-term Covid. This research found that 85% of patients reported at least four lasting neurological problems at least six weeks after their acute infections.

For follow-up, the team continued to interview 52 of the original participants, who were patients at the university’s Neuro COVID-19 clinic — a long-running Covid clinic — for up to 18 months. The cohort was made up of three quarters of women and the average age was 43 years. Nearly 80% were vaccinated and all had mild Covid symptoms that did not require hospitalization.

Most neurological symptoms persisted after an average of 15 months, according to the study. Although most patients reported improvements in their cognitive function and fatigue, the symptoms had not completely resolved and were still affecting their quality of life.

“Many of these patients still have cognitive difficulties that prevent them from working as before,” said study co-lead Dr. Igor Koralnik, head of neuroinfectious diseases and global neurology at Northwestern Medicine, who oversees the Neuro COVID-19 Clinic.

The study also found that certain symptoms, including heart rate and blood pressure variation, as well as gastrointestinal issues, increased over time, while loss of taste and smell tended to lessen. improve. Vaccination against Covid did not alleviate symptoms, but neither did it make Covid worse for long.

The Northwestern study did not examine why some of the symptoms persist and others disappear or why they occur in the first place.

“The next step for that is finding out what causes long Covid in the first place and why some people get it and some don’t,” Koralnik said.

Dr Avindra Nath, clinical director of the National Institute of Neurological Disorders and Stroke at the National Institutes of Health, who was not involved in the new research, said one hypothesis is that symptoms in long Covid patients are the result of damage caused by the body’s inflammatory response to the coronavirus. Any viral infection activates inflammatory cells throughout the body, including the brain. The inflammation is supposed to attack the invading virus, but it also damages brain cells and neurons in the process. SARS-CoV-2, the virus that causes Covid, triggers a particularly strong inflammatory response, he said.

“Covid is probably the most severe respiratory illness we’ve ever had, so it’s no surprise we’re seeing long-term effects from it,” Nath said.

Dr. Panagis Galiatsatos, an assistant professor of medicine and a pulmonary and critical care physician at Johns Hopkins Medicine in Baltimore, who was not involved in the study, said continuing to track long-lasting symptoms was crucial to help experts to separate the long symptoms of Covid from those of the natural healing process. This, he said, will inform further research that will explore treatment and hopefully ways to provide early diagnosis.

Galiatsatos said it’s normal for a patient to experience fatigue and other symptoms during the normal recovery process after an infection, because fighting off a virus is hard on the body. “But the healing shouldn’t take six months or more,” he said.

“Right now we need time to distinguish between the two groups,” he said. “Patients just have to wait, and it’s really frustrating. But if we had biomarkers to test, we could identify Covid for a long time and intervene early. »

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The search for biomarkers, however, has so far yielded no results.

In a separate study, published in the Annals of Internal Medicine on Monday, researchers from another branch of the NIH — the National Institute of Allergy and Infectious Diseases — performed comprehensive medical exams on 189 longtime Covid patients.

The exams included more than 130 cognitive, blood and imaging diagnostic tests. They also looked for biomarkers that would signal heart and brain damage, as well as kidney and liver damage.

The results were compared to the same examinations carried out in 120 people without Covid for a long time; no differences were identified.

“Despite extensive investigation,” said study lead author Dr. Michael Sneller, an NIH infectious disease specialist, “we were unable to demonstrate any evidence of organ damage” or other physical differences. .

That shouldn’t be taken to mean that patients with Covid for a long time don’t have real disease, Sneller said. Something is happening ; modern medicine has simply not been able to understand what is going on so far.

“Make no mistake, these people are really hurting,” he said. “We don’t give up.”

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