Scientists identify potential culprit behind post-Covid-19 ‘brain fog’

Recovering Covid patients across the world have reported numerous lingering neurological symptoms, including fatigue, memory loss, and confusion, nicknamed ‘brain fog’ or ‘Covid brain’. Scientists may now have found the culprit.

“We were initially approached by our colleagues in critical-care medicine, who had observed severe delirium in many patients who were hospitalised with Covid-19,” says neuro-oncologist Jessica Wilcox, of the Memorial Sloan Kettering Cancer Center, in New York.

Her team’s initial investigations eventually snowballed into a multidisciplinary collaboration between neurology, critical care, microbiology, and neuroradiology specialists to uncover the root cause of this ‘brain fog’.

The researchers examined the cerebrospinal fluid of 18 cancer patients experiencing some form of neurological impairment after contracting Covid-19.

Some degree of ongoing viral infection was initially suspected but discounted after microbiological analysis revealed the patients had indeed recovered from the disease and no longer had the virus in their spinal fluid. 

What they did find in the fluid, however, may provide insight into some of the more debilitating symptoms of so-called ‘long Covid’. 

“We found that these patients had persistent inflammation and high levels of cytokines in their cerebrospinal fluid, which explained the symptoms they were having,” says the co-first author of the study, Jan Remsik.

Cytokines are messenger proteins in the immune system. They can be triggered by the SARS-CoV-2 virus and whipped up into a frenzy known as a ‘cytokine storm’ of potentially fatal excessive inflammation. Cytokine storms have been responsible for the more severe cases of Covid-19 witnessed in ICUs across the globe. 

A similar phenomenon has been witnessed in patients undergoing certain kinds of immunotherapy treatments, such as for cancer, with the suspicion being that the cytokines somehow make their way to the brain, causing a slew of neurological symptoms similar to those found in ‘Covid brain’.

While further study is needed, the initial research suggests that additional treatment with anti-inflammatory medications may alleviate ‘brain fog’ in post-Covid patients. The suggestion is that the nervous and immune systems may be more intertwined than had previously been thought.

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