Similarities to chemotherapy
Studies of the brain after even mild Covid infections show lasting damage to parts of neurons (including their "myelin sheaths") that are essential to cognitive, sensory, and motor function.
Similar damage causes the side effects from aggressive chemotherapy, potentially explaining why Long Covid "brain fog" resembles concentration and memory problems suffered by some cancer patients ("chemo-fog").
Source: Mild respiratory COVID can cause multi-lineage neural cell and myelin dysregulation - ScienceDirect