Unravelling the knot: Investigating avoidance learning in anorexia nervosa

Restrictive eating - a core symptom of anorexia nervosa (AN) - has been conceptualized as a learned avoidance behaviour driven by anorectic fears. The present study aims to unravel the learning processes contributing to food avoidance in individuals with AN. We expect that 1) individuals with AN acquire aversive conditioned responses for stimuli predicting food intake, 2) learned avoidance behaviours persist when no food is offered anymore and 3) avoidance behaviours initially reduce threat expectancies and fear but maintain conditioned responses long-term. 20 patients with AN and 23 healthy controls (HCs) completed an avoidance learning task with high-calorie food, monetary rewards, and an aversive scream as the unconditioned stimuli (US). Patients showed more avoidance, greater fear, reduced eating desires and less liking for the stimulus predicting food-intake than HCs. After learning that no food was delivered anymore, patients continued to use avoidance behaviours. This prevented a further reduction of US-expectancies and fear. Differences in learning between patients and HCs were specific to the US-food. These findings suggest that learned food avoidance is persistent and hinders the extinction of eating-related threat beliefs and fears. Consequently, interventions for AN focusing on the reduction of fear e.g., exposure therapy, should also address avoidance behaviours.