Abstract

Abstract INTRODUCTION This study investigated the changes in functional capacity with disease progression in a well‐characterised cohort of patients diagnosed with frontotemporal dementia (FTD) and Alzheimer's disease (AD) presentations. METHODS We recruited 126 behavioural variant FTD (bvFTD), 40 progressive nonfluent aphasia (PNFA), 64 semantic dementia (SD), 45 logopenic progressive aphasia (LPA), and 115 AD patients. Functional capacity was measured annually over ∼7 years using the Disability Assessment for Dementia. RESULTS Linear mixed effects models revealed the bvFTD group demonstrated disproportionate functional impairment at baseline and over the study period. Functional capacity among the other syndromes showed a more uniform pattern of decline, with less severe functional impairment at baseline and ∼7%–10% mean annual decline. Baseline correlations indicated different mechanisms supporting basic and complex functional proficiency among the groups. DISCUSSION Our findings demonstrate distinct functional profiles across dementia syndromes with disease progression. Identifying progression milestones across syndromes will improve clinical management. Highlights bvFTD shows severe functional impairment at baseline and over time. PNFA, SD, LPA, AD: less severe baseline functional impairment; more uniform decline. General cognition is related to IADLs, but not BADLs, in all groups. Behavioural disturbances relate to IADLs and BADLs in bvFTD and SD. Behavioural‐ADL relations are more mixed in PNFA, LPA, and AD.