From the article:
“…two new studies published in the New England Journal of Medicine shed further light on the profound toll of COVID-19 on cognitive health.” And in other studies cases “with mild to moderate COVID-19 showed significant prolonged inflammation of the brain and changes that are commensurate with seven years of brain aging.”
EDIT: I think Musk went of the rails after he got COVID, I speculate. It’s my own take on creating a conspiracy theory.