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

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.

Keywords: Alzheimer's disease; activities of daily living; frontotemporal dementia; longitudinal assessment; primary progressive aphasia.

FIGURE 1

Predicted Disability Assessment for Dementia (DAD) instrumental activities of daily living (IADL), and DAD basic activities of daily living (BADL) scores over time. Note: Values are means and standard error of the mean from the linear mixed effects model.

FIGURE 2

Spearman's rank‐order correlations between Disability Assessment for Dementia (DAD) instrumental activities of daily living (IADLs) and basic activities of daily living (BADLs) and the Addenbrooke's Cognitive Examination–Third edition (ACE‐III) total and Cambridge Behavioural Inventory‐Revised (CBI‐R) subdomain measures at baseline in each group. Floating lines represent the 95% confidence intervals (CIs). Evidence of correlation is demonstrated when both lower and upper CI values do not include zero. Note that the lower ACE‐III scores indicate worse cognition, while higher CBI‐R scores reflect greater behavioural disturbance.