383 Ch 382. Frontotemporal Dementia (FTD)

FTD = 2nd most common dementia in age < 65 (after AD); spectrum of disorders with frontal/temporal lobe degeneration；three clinical syndromes: (1) behavioral variant FTD (bvFTD) = personality + behavior + executive change (apathy, disinhibition, loss of empathy, perseveration, hyperorality); (2) primary progressive aphasia (PPA) = language-dominant: semantic variant (svPPA, loss of semantic knowledge + surface dyslexia), nonfluent/agrammatic variant (nfvPPA, agrammatic + apraxia of speech), logopenic variant (lvPPA, often AD pathology)；(3) FTD-motor = FTD + ALS (FTD-ALS) or PSP/CBS overlap；pathology: heterogeneous — FTD-TDP (most common ~ 50%, C9orf72 hexanucleotide expansion AD) + FTD-tau (Pick, CBD, PSP — 4R or 3R or mixed) + FTD-FUS; genetic ~ 30-50%: C9orf72 (most common, AD), MAPT, GRN, TBK1, VCP；no disease-modifying — supportive + behavioral + speech therapy。