Heated yoga thaws depression: A dose-response analysis from a randomized controlled trial.

BACKGROUND

Heated yoga has promise as an adjunctive and standalone treatment for depression, yet the dose-response relationship is not well understood. This secondary analysis of a randomized controlled trial evaluated the relationship between yoga "dose" and change in depressive symptoms.

METHODS

Eighty adults with moderate-to-severe depression (Inventory of Depressive Symptomatology-Clinician Rated [IDS-CR] ≥23) were randomized to an 8-week (1) community-based heated yoga intervention (90 min per session, encouraged at least twice weekly) or (2) a waitlist-first control group that subsequently received the same intervention after their waitlist period. Data from both intervention phases were pooled to examine the relationship between class attendance ("dose") and change in depressive symptoms using linear regression and mixed-effects models.

RESULTS

Most variability in symptom change occurred within, rather than between, groups, indicating that the yoga-first and waitlist-first groups' yoga periods could be combined (between-group variance = 18.07; residual variance = 93.36). Greater class attendance predicted larger reductions in clinician-rated depressive symptoms, demonstrating a significant linear dose-response relationship ( β=-0.72, SE=0.24, t(52)=-2.94, p<.005), with each additional class corresponding to an estimated 0.72-point improvement in IDS-CR scores. Reductions in depressive symptoms increased proportionally across the observed dose range, with no evidence of a benefit plateau.

CONCLUSION

Exposure to heated yoga was linearly associated with reductions in depression severity, with no evidence of a plateau across the observed dose range. Future studies that randomize participants to different attendance prescriptions are needed to define optimal dosing thresholds and longer-term saturation effects.

TRIAL REGISTRATION: NCT02607514.