Multidimensional Apathy in Behavioral Variant Frontotemporal Dementia, Primary Progressive Aphasia, and Alzheimer Disease

Abstract

Apathy is prevalent in dementia, such as behavioral variant frontotemporal dementia (bvFTD), primary progressive aphasia (PPA), and Alzheimer disease (AD). As a multidimensional construct, it can be assessed and subsumed under a Dimensional Apathy Framework. A consistent apathy profile in bvFTD and PPA has yet to be established. The aim was to explore apathy profiles and awareness in bvFTD, PPA, and AD. A total of 12 patients with bvFTD, 12 patients with PPA, 28 patients with AD, and 20 matched controls, as well as their informants/carers, were recruited. All participants completed the Dimensional Apathy Scale (DAS), assessing executive, emotional, and initiation apathy subtypes, a 1-dimensional apathy measure, depression measure, and functional and cognitive screens. Apathy subtype awareness was determined through DAS informant/carer and self-rating discrepancy. Apathy profile comparison showed patients with bvFTD had significantly higher emotional apathy than patients with AD ( P < .01) and significantly higher apathy over all subtypes than patients with PPA ( Ps < .05). Additionally, patients with bvFTD had significantly lower awareness for emotional apathy ( P < .01) when compared to patients with AD and PPA. All patient groups had significant global apathy over all subtypes compared to controls. The emergent apathy profile for bvFTD seems to be emotional apathy (indifference or emotional/affective neutrality), with lower self-awareness in this subtype. Further, lower self-awareness for executive apathy (lack of motivation for planning, organization, or attention) differentiates bvFTD from PPA. Future research should investigate the cognitive and neural correlates as well as the practical impact of apathy subtypes.