Language impairments in behavioural variant frontotemporal dementia: a comparative study with semantic dementia.

INTRODUCTION: Recent evidence suggests that individuals with behavioural variant frontotemporal dementia (bvFTD) may experience language changes in a similar, but less severe manner, than what is observed in semantic dementia (SD). Few studies, however, have specifically compared these patient groups or considered the cognitive underpinnings. To explore this in more depth, this study aimed to profile patterns of language performance within both "probable" and "possible" categories of bvFTD and to compare them to SD, while also considering the relationships between language and executive function measures. METHODS: Participants included 106 probable bvFTD, 43 possible bvFTD, 42 SD, and 112 healthy controls from the FRONTIER clinic. Data analysed included the Addenbrooke's Cognitive Examination (ACE-III), single word processing (SYDBAT) and executive function measures (word generativity, mental flexibility, response inhibition and working memory). RESULTS: Naming and semantic association impairments frequently occurred in probable bvFTD (51% and 49% respectively). Approximately one quarter of possible bvFTD patients also showed language impairments. The SD pattern of pronounced naming impairment as compared to other single word tasks, was not found in the bvFTD groups. Semantic measures from the ACE-III predicted language performance in bvFTD groups; response initiation and suppression also emerged as a significant predictor. CONCLUSION: Naming and semantic association deficits commonly arise in probable bvFTD, but may also be observed in some patients with possible bvFTD. The pattern of impairments in bvFTD were not wholly consistent with those seen in SD. Both semantic and executive function measures may be associated with language performance deficits observed in bvFTD.