Disturbance of Emotion Processing in Frontotemporal Dementia: A Synthesis of Cognitive and Neuroimaging Findings

Accurate processing of emotional information is a critical component of appropriate social interactions and interpersonal relationships. Disturbance of emotion processing is present in frontotemporal dementia (FTD) and is a clinical feature in two of the three subtypes: behavioural-variant FTD and semantic dementia. Emotion processing in progressive nonfluent aphasia, the third FTD subtype, is thought to be mostly preserved, although current evidence is scant. This paper reviews the literature on emotion recognition, reactivity and expression in FTD subtypes, although most studies focus on emotion recognition. The relationship between patterns of emotion processing deficits and patterns of neural atrophy are considered, by integrating evidence from recent neuroimaging studies. The review findings are discussed in the context of three contemporary theories of emotion processing: the limbic system model, the right hemisphere model and a multimodal system of emotion. Results across subtypes of FTD are most consistent with the multimodal system model, and support the presence of somewhat dissociable neural correlates for basic emotions, with strongest evidence for the emotions anger and sadness. Poor emotion processing is evident in all three subtypes, although deficits are more widespread than what would be predicted based on studies in healthy cohorts. Studies that include behavioural and imaging data are limited. Future investigations combining these approaches will help improve the understanding of the neural network underlying emotion processing. Presently, longitudinal investigations of emotion processing in FTD are lacking, and studies investigating emotion processing over time are critical to understand the clinical manifestations of disease progression in FTD.     

Disrupted Face Processing in Frontotemporal Dementia: A Review of the Clinical and Neuroanatomical Evidence

Faces play an integral role in day-to-day functioning, particularly for social interactions where dynamic and rapid processing of information is vital. Analysis of faces allows an individual to ascertain a wide range of information including deciphering mood and identity, with these assessments directing an individual’s subsequent response and behaviours. The prominent social and emotional deficits observed in frontotemporal dementia (FTD), a younger-onset dementia syndrome, may in part reflect a breakdown of the face processing network. Different subtypes of FTD present with divergent patterns of atrophy, although damage is predominantly confined to the frontal and temporal lobes. Specific predictions regarding the role of frontal and temporal regions in face processing have been proposed in the model outlined by Haxby et al. Trends in Cognitive Sciences, 4(6), 223–233 (2000). This model presents a parsimonious method by which to understand face processing in FTD while concurrently allowing assessment of the predictive value and applicability of such a model. By applying the Haxby model to the existing FTD literature, this review presents both direct and indirect evidence of a breakdown in key elements of the face processing network. The type and degree of breakdown appears to differ as a function of FTD subtype and associated brain atrophy. The evidence presented in this review and its relationship with predictions of the Haxby model provides impetus and direction for future research investigating face processing in FTD.     

The Cerebellum in Frontotemporal Dementia: a Meta-Analysis of Neuroimaging Studies

Neuropsychology Review - Frontotemporal dementia (FTD) is a neurodegenerative brain disorder primarily affecting the frontal and/or temporal lobes. Three main subtypes have been recognized:...