A randomized controlled pilot trial of low and high arousal resilience interventions for depressive symptoms.

BACKGROUND: To cope with chronic stress, which can contribute to depression, humans often pursue arousal-reducing activities. Yet, hormetic stressors (intermittent, acute stressors) might also reduce chronic stress. PURPOSE: We compared the effects of arousal-reducing and arousal-enhancing interventions on depressive symptoms and perceived stress. METHODS: Female adults (N = 141; predominantly White, 63%, and Asian, 34%) reporting high perceived stress were randomized to 1 of 4 three-week stress resilience interventions in 2019-2020. Low arousal conditions included mindfulness meditation or slow breathing with warm showers (Control). Hormetic stress conditions included fast paced breathing with cold showers (the Wim Hof Method; WHM) or high-intensity interval training. We assessed depressive symptoms and perceived stress at baseline, postintervention, and 3 months later, and cortisol reactivity to a lab stressor. RESULTS: At postintervention, all 4 groups had decreases in depressive symptoms (15.93% reduction, r = .76, P < .001) and perceived stress (9.70% reduction, r = .48, P < .001), with no group differences. "As treated" analysis showed the WHM group had better maintenance of reduced depression 3 months later (r = .17, P < .01). The WHM group had greater increases in daily positive affect across days (r = .16, P ≤ .05) and at postintervention (r = .17, P < .015) compared to the control group. Groups were similar in cortisol reactivity pre- and postintervention. CONCLUSIONS: All groups experienced reduced stress and depressive symptoms and did not differ from each other after 3 weeks. After 3 months, a post hoc analysis of adherent subjects showed the WHM group had more sustained improvements in depression and positive affect, a finding that needs replication with larger and more diverse samples.