A quick Google search reveals that cognitive deficit seems to be a common consequence in any critically ill patient, not just Covid-19 This study[1] of just one example: Cognitive dysfunction is an important long-term complication of critical illness associated with reduced quality of life, increase in healthcare costs, and institutionalization And the numbers are certainly high: Cognitive impairment was identified i…
According to another study, covid-19 can infect brain tissue specifically: https://www.altex.org/index.php/altex/article/view/1924
That may be why it is particularly dangerous to brains, more so than other viruses.