A matched PET and pathology study links TSPO-PET signal in frontotemporal dementia to a higher burden of CD68-positive phagocytic microglia across both tau and TDP-43 pathologies. The work supports TSPO binding as a proxy for an inflammatory microglial phenotype, improving interpretability of a widely used neuroimaging target. Separately, an observational pilot study found alpha-synuclein seeding activity is more frequent among people with persistent post-COVID smell loss than among infected controls with normal smell and healthy participants. If validated, it would broaden the set of at-risk phenotypes monitored for synucleinopathy-related processes. Both findings push neurodegeneration research toward phenotype-linked measurement strategies—connecting imaging or biological seeding signals to specific underlying cellular or clinical contexts.