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British and Swiss biologists have studied the pathways of the SARS-CoV-2 coronavirus in the brain in mice and identified the types of damage it causes there. The results obtained explain the cause of the "brain fog" and other neurological complications in patients with COVID-19. Report informs with reference to RIA Novosti that the article is posted on the bioRxiv preprint server.
Initially, the new coronavirus infection was identified as severe acute respiratory syndrome (SARS), but further observations showed that the virus also affects other organs, where it uses the ACE2 receptor to enter cells - the kidneys, heart, lungs, and also the brain.
Many people during and after the COVID-19 illness complain of memory problems, cognitive impairment, insomnia, anxiety, as well as the characteristic "brain fog", manifested in drowsiness, apathy, decreased reaction, distraction of consciousness and increased fatigue. In elderly patients, coronavirus exacerbates Alzheimer's and Parkinson's and other manifestations of dementia. However, the mechanism of how the coronavirus infects the brain has remained poorly understood so far.
Scientists at the Universities of Zurich and Liverpool have used genetically modified mice with the human hACE2 receptor as a model to study the effects of coronavirus on the brain. The authors intranasally infected animals with low or high doses of SARS-CoV-2 and looked at how the virus affects the brain.
Observations showed that seven days after the introduction through the nose, the virus entered the brain through the olfactory bulb. The researchers made this conclusion, as they found that the virus spread in the olfactory epithelium and neurons of the olfactory bulb, as well as in the frontal regions of the brain and the regions that have connections with the olfactory bulb - the hippocampus, thalamus and hypothalamus. At high doses, scientists have observed that the virus spreads more widely in the brain and spinal cord.
The researchers note that in the front of the brain there are several areas of the cortex responsible for memory, attention, and executive functions that can be impaired during infection. This explains many of the neurological symptoms of COVID-19.
