Compassion training influences state but not trait level heart-rate variability within severe depression

Heart-rate variability (HRV) is a marker of parasympathetic nervous system activity, and is a robust predicter of improved mental and physical health. Current psychotherapeutic interventions are effective at reducing self-report depressive symptoms, but few have improved HRV within a sample of severe depressive symptoms. This study explores the impact of a brief Compassion Focused Therapy exercise (CFT) on HRV. Results suggested that a brief CFT exercise can successfully target depressive physiology, at two distinct timepoints, pre- and post-a two-week self-directed training period. Specifically, we first show that CFT can significantly improve HRV at the state level, but not at the trait level after a two-week intervention. Second, CFT can increase a subset of participants HRV above a clinical cut-off of low resting HRV. Third, the frequency of practice (i.e., listening to the audio recording) during the self-directed training component was very low, with 50% not accessing the practice. Finally, during the CFT exercise at post-two-week training HRV decreased across time, indicating participants had a greater engagement in the threat component of the CFT exercise - a feature to be more fully examined in prospective studies. This study suggests the value of future research with larger-scale randomized control trials, to further explore the modulation of parasympathetic physiology using compassion practices.