Why Should I Care? Dimensions of Socio-Emotional Cognition in Younger-Onset Dementia

Background: Skills such as empathy and emotion recognition rely on a multi-dimensional socio-emotional system. Increasingly, evidence suggests that socio-emotional cognition is affected in frontotemporal dementia and Alzheimer's disease (AD), to varying degrees. However, the specific dimensions of socio-emotional behavior and their neuroanatomical correlates have been relatively unexplored. Objective: The current study aimed to: (i) determine how different dimensions of socio-emotional cognition are affected in behavioral-variant frontotemporal dementia (bvFTD), semantic dementia (SD), and AD; (ii) investigate insight into socio-emotional cognition; (iii) identify the neural correlates subserving dimensions of socio-emotional cognition. Methods: Sixteen bvFTD, 15 SD, 10 AD patients, and 17 controls were included. Each participant and a nominated 'informant' completed the socio-emotional questionnaire; a 30-item rating scale assessing five dimensions of socio-emotional cognition (empathy, emotion recognition, social conformity, antisocial behavior, sociability). Results: SD and bvFTD participants were rated lower on measures of empathy and emotion recognition compared to AD participants and Controls, while other dimensions were relatively intact. In contrast, participants with AD were rated similarly to Controls across all dimensions. SD and bvFTD groups demonstrated reduced insight into socio-emotional dysfunction. Grey matter intensity in the temporal regions correlated with empathy and emotion recognition. Social conformity was associated with the orbitofrontal cortex and amygdala. Conclusion: Distinct profiles in typically presenting bvFTD, SD, and AD illustrate preliminary evidence of the utility of socio-emotional cognition in diagnostic clarification. This is an important starting point in understanding socio-emotional functioning in younger-onset dementia, paving the way for targeted management and interventions.