A meta-analytic review of the impact of intranasal oxytocin administration on cortisol concentrations during laboratory tasks: Moderation by method and mental health

Background: A large body of research has examined the acute effects of intranasal oxytocin administration on social cognition and stress-regulation. While progress has been made with respect to understanding the effect of oxytocin administration on social cognition in clinical populations (e.g. autism, schizophrenia), less is known about its impact on the functioning of the hypothalamic-pituitary-adrenal (HPA) axis among individuals with a mental disorder. Method: We conducted a meta-analysis on the acute effect of intranasal oxytocin administration on the cortisol response to laboratory tasks. The search yielded eighteen studies employing a randomized, placebo-controlled design (k = 18, N = 675). Random-effects models and moderator analyses were performed using the metafor package for the statistical program R. Results: The overall effect size estimate was modest and not statistically significant (Hedges G = -0.151, p = 0.11) with moderate heterogeneity in this effect across studies (I-2 = 31%). Controlling for baseline differences in cortisol concentrations, moderation analyses revealed that this effect was larger in response to challenging laboratory tasks that produced a robust stimulation of the HPA-axis (Hedges g = -0.433, 95% CI[-0.841, -0.025]), and in clinical populations relative to healthy controls (Hedges g = -0.742, 95% CI[-1.405, -0.078]). Conclusion: Overall, oxytocin administration showed greater attenuation of the cortisol response to laboratory tasks that strongly activated the HPA-axis, relative to tasks that did not. The effect was more robust among clinical populations, suggesting possible increased sensitivity to oxytocin among those with a clinical diagnosis and concomitant social difficulties. These data support the view that oxytocin may play an important role in HPA dysfunction associated with psychopathology. (C) 2014 Elsevier Ltd. All rights reserved.