Compassion training influences heart-rate variability within severe depression

Heart-rate variability (HRV) is a marker of parasympathetic nervous system activity, and is a robust predictor 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 symptomatology. This study explores the impact of a brief Compassion Focused Therapy exercise (CFT) on HRV response. Results indicate that a brief CFT exercise can successfully target depressive physiology via increasing HRV, at two distinct timepoints, pre- and post- a two-week self-directed training period, even when controlling for respiration. Specifically, we first show that CFT can significantly increase HRV. Second, we show that CFT exercise can increase a subset of participants' HRV level above a clinical cut-off value of low resting-HRV. Third, we describe how participant engagement with the CFT audio during the two-week training was very low, with 50% of individuals not accessing the audio during this period. Finally, during the CFT practice at post-two-week training, HRV was shown to decrease across time, potentially indicating a greater participant engagement in the 'threat' component of the exercise. Almost 50% of the sample did not listen to the CFT exercise during the two-week training period, a feature that has implications for self-directed delivery of experimental and treatment interventions. CFT can significantly improve HRV for those with severely depressed symptoms at the state-level, and future work should continue to examine CFT's effectiveness for those with depression.