I'm looking through you: Mentalizing in frontotemporal dementia and progressive supranuclear palsy

Mentalizing and emotion recognition are impaired in behavioral variant frontotemporal dementia (bvFTD). It is not clear whether these abilities are also disturbed in other conditions with prominent frontal lobe involvement, such as progressive supranuclear palsy (PSP). Our aim was to investigate social cognition (facial emotion recognition, recognition of social norms violation and mentalizing) in bvFTD and PSP. The neural basis of these functions in PSP and bvFTD groups, by analysis of structural neuroimaging, were also investigated. Twenty-three bvFTD patients, 21 PSP patients and 23 healthy controls were included. All participants underwent 3T brain MRI and a full cognitive exam including the short version of Social and Emotional Assessment (Mini-SEA), which is composed of a facial emotion recognition test (FERT) and the faux pas test. Two components of the faux pas test were distinguished: a score assessing the recognition of social norms violation and a score assessing mentalizing. Compared to controls, bvFTD and PSP patients had significantly reduced scores in all tests of social cognition but did not differ on these measures. PSP and bvFTD had cerebral atrophy in critical regions for social cognition processes, when compared to controls. The cortical correlates of emotion recognition partially overlapped in bvFTD and PSP, with correlations retrieved within the frontal medial cortex, cingulate, insula and limbic structures. PSP and bvFTD patients also displayed similar patterns of brain correlations for the composite score of social norms, with a significant cluster in anterior temporal lobes. Mentalizing scores were associated with frontal and temporal poles bilaterally, in both bvFTD and PSP. These findings support previous observations that PSP patients exhibit impairment in complex cognitive abilities, such as mentalizing. Moreover, these data extend previous findings showing that PSP and bvFTD share key clinical, cognitive and neuroimaging features.