Behavioural and cognitive profiles in frontotemporal dementia and Alzheimer's disease: a longitudinal study.

introductionLongitudinal comparative characterisation of dementia syndromes may aid differential diagnosis, prognostication and intervention implementation.

methodsWe compared the behavioural and cognitive characteristics of 84 behavioural variant frontotemporal dementia (bvFTD), 29 left and 14 right-dominant semantic dementia (SDL and SDR) and 49 Alzheimer's disease (AD) patients over a follow-up period of 2.4 ± 1.6 years using the Cambridge Behavioural Inventory Revised (CBI-R) and Addenbrooke's Cognitive Examination third edition (ACE-III).

resultsLinear mixed modelling of time effects found progression of all CBI-R domains, aside from sleep, beliefs and mood domains, and all ACE-III domains. Modelling of group effects found that bvFTD had greater symptoms than AD in most CBI-R domains. Notably, SDL and SDR compared differently with AD and bvFTD; whilst SDR did not differ significantly from bvFTD in any CBI-R domain, SDL had less severe symptoms than bvFTD in everyday skills, motivation, sleep and eating habits; whilst SDL had greater disturbances in abnormal behaviour and stereotypic behaviour than AD, SDR had greater disturbances in addition in motivation and eating habits. Motivation, eating habits, abnormal behaviour and stereotypic behaviour were the most frequently different behavioural domains between groups.

conclusionWe have shown that the combined, longitudinal use of existing behavioural and cognitive assessments could capture distinct clinical profiles of common and rare dementia syndromes. Our findings also highlight the importance of select behavioural domains such as motivation and the usefulness of separate clinical characterisations of SDL and SDR.