Understanding behaviour and function in frontotemporal dementia: developing better intervention approaches

Abstract

Frontotemporal dementia (FTD) is the second most common younger onset dementia after Alzheimer’s disease, and comprises three primary clinical variants: behavioural variant (bvFTD), and two language variants divided according to the pattern of language deterioration: non-fluent primary progressive aphasia (nfvPPA) and semantic variant primary progressive aphasia (svPPA). FTD is associated with marked behavioural symptoms and impairments to everyday function in activities of daily living, which are both included as markers of disease progression in clinical and in research settings. Despite this, the relationship between these two significant variables remains unknown. The relationship between behavioural symptoms and functional impairments in FTD is addressed in this thesis. Further to this, the implications of these symptoms are explored in the context of providing a tailored non-pharmacological intervention to an FTD cohort. In order to achieve these objectives, a series of five studies were undertaken. The first study investigated the relationship between behavioural changes, cognitive symptoms, and functional disability in the primary progressive aphasias. This study showed similar functional abilities in people with svPPA and nfvPPA, but differing patterns of behavioural symptoms, and different factors contributing to their functional impairments. The second study explored the longitudinal relationship between behaviour and function in bvFTD and svPPA. While bvFTD was more functionally impaired, both groups shared overlapping baseline behavioural symptoms. Apathy was a strong contributor to functional decline in both groups, whereas stereotypical behaviours only contributed for bvFTD. The third study built on these findings by identifying four distinct behavioural phenotypes of bvFTD (based on levels of apathy and disinhibition), with differing patterns of functional decline and brain atrophy. The final two studies pertained to the implementation of the Tailored Activity Program (TAP) with a cohort of people with FTD and their carers. TAP is an occupational therapy based intervention that involves working collaboratively with carers and using tailored activities to engage the person with dementia. The feasibility and acceptability of this intervention is described, highlighting the importance for further and rigorous intervention trials in FTD. Finally, two case studies are presented, which demonstrate the applicability of TAP for people with FTD. The studies presented in this thesis shed light on the role of behavioural symptoms in the functional impairments seen in FTD, and provide support for the use of TAP as an intervention approach for people with FTD. These outcomes provide important data to contribute to the development of better management and intervention approaches within the FTD spectrum.