Evoked emotions in anorexia nervosa: neural and behavioural correlates of social-emotional processing

TL;DR

People with anorexia nervosa show reduced positive facial expressions and mood in response to positive films, but brain scans show similar emotional processing between groups.

Contribution

Replicates altered reactivity to positive stimuli in AN and validates a naturalistic emotional processing task using fMRI.

Findings

AN group showed reduced positive facial expressions and lower mood ratings for positive films.

fMRI revealed widespread brain activation in emotional regions but no group differences in response.

Task validity confirmed by consistent brain activation across groups for emotional films.

Abstract

Previous work suggests people with anorexia nervosa (AN) display reduced facial expression of emotion. This may influence illness progression as blunted emotional reactions can negatively impact social relationships and increase isolation. The present study aimed to replicate and further build on previous findings by examining facial and brain responses to naturalistic, emotional films. In total, 141 women (71 AN/weight restored AN, 70 healthy comparison) completed two tasks in a fixed order: 1.) facial affect task and 2.) functional magnetic resonance imaging (fMRI) task. In both tasks, participants reacted to positive, neutral, and negative films, and rated their mood after each one. The effects of group and film category on facial expressions, brain responses, and mood ratings were examined. The AN group displayed reduced positive facial affect over time and lower self-reported mood in response to positive but not negative or neutral films. The fMRI task revealed no significant group differences in response to positive, neutral, or negative films. However, there was widespread activation of occipital, parietal, temporal, and frontal regions in response to the emotional films across groups. The behavioural findings replicate previously reported altered reactivity to positive films in AN. Additionally, task-related brain activation was observed in regions typically associated with the processing of naturalistic emotional stimuli, suggesting the task was valid. However, the lack of group differences during the fMRI task raises questions about whether the behavioural differences could be related to slower warming up to the task among those with AN.

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