Since the outbreak of the coronavirus pandemic in late 2019, people have reported experiencing continued symptoms long after their infection has ended, commonly called Long Covid. Cognitive issues, or "brain fog", are one of the most often reported of these post-infection symptoms, which are thought to affect one in eight of all people infected.
The cause of these lingering cognitive issues has been a mystery to scientists, but new research suggests that inflammation caused by an overactive immune response could be the biological mechanism causing the persistent confusion, fatigue, and headaches reported by sufferers.
Research lead at the University of California San Francisco Joanna Hellmuth, MD, told MedPage that this research was essential to finding treatment for the condition, saying: "there are not yet effective laboratory tests or treatments for COVID-associated cognitive changes, in part because we do not understand the underlying biology."
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Hellmuth's team of researchers took samples of cerebrospinal fluid of 13 patients suffering from cognitive Long Covid symptoms 10 months after their original infection. They found higher levels of two proteins linked to inflammation, c-reactive protein and serum amyloid a, in the spinal fluid of those with post-Covid brain fog than those who had Covid but no lasting symptoms.
The team also found a spike in markers indicating that veins in the brain had been stressed and forced to undergo healing and repair, pointing towards an immune reaction in the brain to coronavirus causing this brain fog.
"This is an important observation. It suggests vascular injury and repair in the brain may set up the inflammation," said Dr. Avindra Nath, the clinical director of the National Institute of Neurological Disorders.
This adds to the recent findings of the UK Biobank research team, looking into grey matter volume in Covid patients, which showed a reduction in the thickness of the important brain tissue, as well as an overall decrease in the whole size of the brain.
This UCSF research paper, due to be presented at the American Academy of Neurology, only covered a small sample of 13 people with Long Covid, but Hellmuth hopes it will prompt further work in the field of Long Covid study
Dr Nath said: "People say you need to know the mechanism behind this. And I would say, yes, that's absolutely true: you don't want to rush because you don't want to cause harm.
"But an argument I would make is that with COVID, you're dealing with a very different beast. You've got billions of people infected. It takes years to figure out mechanisms. Can we really afford to wait that long?"
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