Potential shortcomings in current studies on the effect of intranasal oxytocin in Anorexia Nervosa and healthy controls-A systematic review and meta-analysis

Rationale The psychopathology of anorexia nervosa (AN) includes altered social cognition and information processing of fear and anxiety. Oxytocin, a neuromodulating hormone, may influence these functions and could be valuable for the treatment of AN. Objective The current study aimed at reviewing the effect of intranasal oxytocin (IN-OT) on attentional bias (AB) and emotion recognition (ER) in AN. Methods A systematic literature review was done for free-text and the MeSH-terms: anorexia nervosa, feeding and eating disorders, and oxytocin. Six publications, reporting from 4 unique clinical trials, were included in this review. A meta-analysis was conducted to examine the effects of IN-OT on AB towards food images and ER on healthy controls (HC) and patients with AN. Results Overall, IN-OT did not influence AB towards food images (effect size = 0.20 [- 0.16, 0.57],p= 0.28) and had no effect on ER (effect size = - 0.01 [- 0.27, 0.26],p= 0.97) in patients with AN and healthy control (HC) subjects collectively. Assessing HC and AN separately in subgroup analyses did not show any significant effect on AB and ER in neither of the subgroups. All tests were done between 15 and 55 min post-administration of IN-OT, while peak concentration in the cerebrospinal fluid has been determined to be at 75 min. Conclusion The current level of evidence is moderate showing no effect of IN-OT on AB or ER in AN. However, brain exposure may not have been sufficient which future studies with IN-OT need to ensure by considering dose and dose-to-task interval.