DECLINE IN INSTRUMENTAL ACTIVITIES OF DAILY LIVING IS MORE MARKED IN BEHAVIOURAL VARIANT FRONTOTEMPORAL DEMENTIA THAN IN ALZHEIMER’S DISEASE

Abstract

Different subtypes of dementia show different levels of impairment in everyday functioning. However, there has been little focus on the decline of individual daily activities over time, and how these might vary between subtypes of dementia. The objective of this study was to assess and compare the trajectories of decline of 10 individual instrumental activities of daily living (IADLs) (bills; taxes; shopping; hobbies; using kitchen appliances; preparing a meal; keeping track of current events; paying attention; remembering appointments; travelling) between behavioural variant frontotemporal dementia (bvFTD) and Alzheimer's disease (AD). This study included data from the Uniform Data Set of the National Alzheimer's Coordinating Center (NACC), which collects annual data on demographics, neuropsychological testing, clinical diagnosis, and assessments such the Functional Assessment Questionnaire (FAQ). The dataset was locked in November 2012, and data were extracted up to that occasion. There were a maximum of eight data points for each patient. Independent t-tests were used to assess variations in everyday functioning between dementia types at baseline. Linear mixed effect modelling was performed to explore the longitudinal functional decline between dementia subtypes. The model included random intercepts for subject IDs to account for any correlation between the repeated measures within subjects. In total, data from 3351 patients (306 bvFTD and 3045 AD) were analysed. At baseline, bvFTD patients were impaired to a greater degree with bills (mean difference, d=0.8, p<0.001), taxes (d=0.8, p<0.001), shopping (d=0.6, p<0.001), hobbies (d=0.7, p<0.001), using kitchen appliances (d=0.5, p<0.001), meal preparation (d=0.7, p<0.001), current events (d=0.4, p<0.01), paying attention (d=0.6, p<0.001), and travel (d=0.6, p<0.01) compared to AD patients. BvFTD patients were more impaired on the total FAQ (mean=20.1, standard deviation, sd=10.4) than AD patients (mean=15.2, sd=12.0). Longitudinally, analysing all time points together using linear mixed model, bvFTD patients had lower scores than AD patients on everyday activities (coeff.=-3.95, 95% CI:2.45–5.44, p<0.001). Findings from this study can have important implications for clinical practice in aiding the management of different dementia subtypes, by understanding in depth how different IADLs deteriorate throughout the disease across different types of dementia.