Besides important progress in the understanding of the pathological substrate of COVID-19-associated brain disease, major insights into mechanisms of neurodegeneration in human disease have been provided in neuropathological studies published in 2021. Recently developed techniques, which allow the simultaneous detection of a large battery of different molecules within single cells, have proven useful in the analysis of disease mechanisms in experimental and human neuroinflammatory conditions. They have elucidated protective and detrimental effects of activated microglia, which act in a stage and context-dependent manner in the induction and propagation of neurodegeneration. In addition, they emphasize the importance of synaptic damage and of selective neuronal vulnerability in the respective diseases. The results provide important new insights with high clinical relevance.
Keywords: Alzheimer’s disease; COVID-19; Microglia; Multiple sclerosis; Neurodegeneration.