Emotion Perception in Behavioral Variant Frontotemporal Dementia and Alzheimer Disease: The Parahippocampal Conundrum

Emotion perception is the capacity that enables humans to correctly identify the cues that guide interpersonal interactions, forming the basis for social behavior. The parahippocampal cortex may contribute to emotion perception by mediating the associations between context and emotion. Individuals with behavioral variant frontotemporal dementia (bvFTD) and Alzheimer disease (AD) appear to show deficits in this process. Investigating emotion perception impairment in these individuals could offer valuable insights into the underlying neurobiological mechanisms.

Participants included a convenience sample of 29 individuals with bvFTD, 25 with AD, and a comparison group of 15 individuals without bvFTD or AD. We performed an extensive neuropsychological assessment and administered the Comprehensive Affect Testing System (CATS) to evaluate the emotion perception process. We then used multiple regression analysis to assess the relationship between CATS main quotient scores and parahippocampal thickness (P ≤ 0.001) obtained from MRI analysis.

Participants with bvFTD scored higher on cognitive tests than participants with AD but showed greater deficits in social behavior. On the CATS, participants with bvFTD had lower scores in all 3 emotional quotients (ie, face, prosody, and global), with a statistically significant correlation to parahippocampal thickness. Participants with AD showed milder deficits in all 3 emotion quotients, with no statistically significant correlation to parahippocampal thickness.

Our data suggest a significant emotion perception deficit in individuals with bvFTD and support the importance of the parahippocampal gyrus in context-emotion associations. Targeted rehabilitation with the objective of improving emotion perception deficits may be beneficial for individuals with bvFTD.