Plasma oxytocin is modulated by mental training, but does not mediate its stress-buffering effect

Based on its role in social processing and stress, oxytocin has been suggested to mediate stress reduction of socioaffective, compassion-based mental training. We tested this hypothesis in the ReSource Project, a 9-month longitudinal mental training study. Participants practiced three different types of mental training, targeting either attentional abilities (Presence Module), socio-affective or socio-cognitive abilities (Affect and Perspective Modules). We investigated plasma oxytocin levels, and their link to cortisol and subjective reactivity to acute psychosocial stress as a function of previous mental training (n = 313). In a subsample (n = 113), to better understand oxytocin's involvement in the effects of socio-affective training, we explored oxytocin, cortisol and subjective experiential responses to a single Loving-kindness Meditation (LKM) conducted after three months of Affect training (versus rest without prior training). We found that, independent of mental training, stress triggered acute oxytocin release. Following a single LKM, however, acute oxytocin release was unaffected. Training effects were only found in overall oxytocin release during both, stress and LKM. Compared to no training, 3-month compassion-based Affect training decreased overall oxytocin levels in the context of psychosocial stress, but increased overall oxytocin levels during LKM. Training-induced changes in overall oxytocin were unrelated to cortisol and subjective stress reactivity. Based on Quintana and Guastella's (2020) theory of oxytocin as an allostatic hormone with anticipatory properties, we interpret training-induced changes in overall oxytocin levels as alterations in the anticipated emotional relevance of specific events. After training socioaffective skills for three months, the stressful situation may have lost its emotional saliency, whereas the meditation technique itself gained emotional relevance. We conclude that changes in peripheral oxytocin release do not mediate stress reduction after mental training, and encourage the investigation of an allostatic concept of oxytocin in future research.

Automated summary

This study examined the relationship between plasma oxytocin levels, cortisol, and subjective stress reactivity to explore the impact of mental training on stress reduction. While stress triggered acute oxytocin release, a single Loving-kindness Meditation did not affect oxytocin release. Compassion-based affect training decreased overall oxytocin levels during stress, but increased levels during meditation, regardless of cortisol and subjective stress reactivity. The findings suggest that changes in peripheral oxytocin release do not mediate stress reduction after mental training, highlighting the potential importance of an allostatic concept of oxytocin.