Investigating language profiles in behavioural variant frontotemporal dementia

Introduction: Recent studies in behaviour variant frontotemporal dementia (bvFTD) have highlighted the presence of language impairments in both ‘possible’ and ‘probable’ bvFTD, with similar patterns of deficits to Semantic Dementia (SD) being observed. However, these studies often included small sample sizes and were primarily conducted with the more impaired, probable bvFTD group, with the possible bvFTD group being overlooked. The mechanisms underpinning the pattern of language deficits in bvFTD are also unclear. Therefore, this study investigated language performance within possible and probable bvFTD, and in relation to SD, as well as the mechanisms underlying the language changes in the two bvFTD groups. Methods: Participants included 106 probable bvFTD, 43 possible bvFTD, 42 SD, and 115 healthy controls who had completed detailed assessment (clinical examination, neuropsychological assessments, and neuroimaging) at the FRONTIER research clinic. Results: Language impairments were found in both of the bvFTD subgroups, but to a lesser extent than SD, and were more prominent in the probable bvFTD group. Naming deficits were commonly observed in the possible bvFTD groups, with both naming and semantic association deficits prevalent in the probable bvFTD group. The SD pattern of significantly lower naming performance in relation to other subtests, however, was not found in either bvFTD group. Both bvFTD groups showed similar mechanisms underpinning language deficits, being primarily semantically driven, but with some executive functioning contributions. Conclusion: The findings highlighted the presence of language deficits in bvFTD and confirmed that mechanisms underlying language changes in bvFTD involve both semantic and executive functions.