Longitudinal changes in functional capacity in frontotemporal dementia and Alzheimer's disease

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.