MAPT and tauopathy: Progressive aphasia is linked to tau-negative pathologies like FTLD-U, while progressive nonfluent aphasia is associated with PiD or CBD. No specific clinical association between language disorder and pathological subgroups was found. Tauopathy patients often show extrapyramidal features indicative of CBD and PSP, aligning with smaller studies that connect rigidity to CBD and pyramidal features of clinical MND to FTLD-U.