Neural correlates of body composition in frontotemporal dementia

Abstract

Frontotemporal dementia (FTD) is associated with complex changes in eating behaviour and metabolism, which potentially affect disease pathogenesis and survival. It is currently not known if body composition changes also exist in FTD, the relationship of these changes to eating behaviour, and whether these changes are centrally mediated. In 28 behavioural variant frontotemporal dementia (bvFTD), 16 Alzheimer’s disease (AD) and 19 controls, body composition was measured using dual x-ray absorptiometry. Changes in body composition were correlated to grey matter atrophy using voxel-based morphometry on high resolution MRI. Behavioural variant frontotemporal dementia was characterised by changes in body composition, with increased total fat mass, visceral adipose area, and android: gynoid ratio compared to control and AD subjects (all p values < .05). Changes in body composition correlated to abnormal eating behaviour and behavioural change (p < .01) and functional decline (p < .01). Changes in body composition also correlated to grey matter atrophy involving a distributed network of neural structures including the hippocampus, the amygdala, nucleus accumbens, insula, cingulate and cerebellum, known to be to central to autonomic control, and also areas involved in reward processing including the thalamus, putamen, accumbens and caudate. Changes in body composition extend the clinical phenomenology in bvFTD beyond cognition and behaviour, with changes potentially mediated by changes in reward and autonomic processing suggesting that these deficits may be central in FTD, and providing targets to modify the neurodegenerative process.