Role of oxytocin in attentional bias and reward-related food intake in binge eating disorder
Final Report Abstract
The aim of the project was to investigate the role of oxytocin signaling pathways in the attentional information processing of food stimuli and their contribution to the regulation of eating behavior in individuals with binge eating disorder (BED) and healthy participants, i.e., a weight-matched and a normal-weight control group. To this end, in a double-blind, placebo-controlled crossover study with within-subjects design, we administered intranasal oxytocin (24 IU) after a standardized meal to briefly increase the endogenous availability of the neuropeptide. We used a pictorial dot probe paradigm in combination with eye-tracking measures to record food-related attentional processing. We considered three distinct attentional biases: Gaze direction (frequency of first fixation on food stimuli relative to first fixation on neutral stimuli), early attentional maintenance (duration of first fixation on food stimuli relative to duration of first fixation on neutral stimuli), and attentional maintenance (total gaze dwell time on food stimuli relative to total gaze duration on neutral stimuli). For the three measures, it was hypothesized that stronger biases toward food would be present in the BED group compared with the control groups and that these biases would be reduced by oxytocin, especially in the BED group. Subsequently, a bogus taste test was performed in which calories consumed in the form of snacks were protocolled. It was hypothesized that oxytocin would lead to a reduction in caloric intake and that the reduction in food intake would be mediated by the reducing effect of oxytocin on food-related attentional biases. We found that, contrary to expectations, there were no increased food-related attentional biases in the BED group compared to the control groups and that there was no reduction in food-related attention by oxytocin. Regarding the effects of oxytocin on hedonic food intake, all groups showed an effect opposite to the hypothesis: oxytocin increased the number of calories consumed. Mediation of the effect of oxytocin on food intake could not be demonstrated. However, an additive effect of oxytocin and (early) attention maintenance was found. In addition to higher food intake due to oxytocin, prolonged viewing of food stimuli was also associated with higher food intake. Our project provides initial evidence that the anorexigenic effect of oxytocin (previously observed in experiments that often included only male participants) might depend on the study population and/or factors unknown so far. Thus, oxytocin might even acutely increase food intake in female individuals. Especially with regard to restrictive eating behavior in BED, this effect should be further investigated.
