Inflammatory biomarker findings from a randomized controlled trial of heated yoga for depression

Abstract

BackgroundBoth heated and non-heated yoga have demonstrated antidepressant effects in randomized controlled trials (RCTs), with a greater number of studies evaluating non-heated yoga. Both heated and non-heated yoga may exert antidepressant effects in part by reducing inflammation. We report the first RCT evaluating the impact of heated yoga on inflammatory biomarkers in participants with moderate-to-severe depression. MethodsAdults (N = 80) were randomized to either a heated yoga or a waitlist group. The heated yoga group attended at least two community heated yoga classes per week for 8 weeks. The waitlist group completed an initial 8-week waitlist period, followed by the same heated yoga intervention. Blood samples were collected at baseline, at 8 weeks, and after the waitlist group completed the heated yoga intervention. Serum levels of inflammatory biomarkers (IFNγ, IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, and TNF-α) were measured. Linear mixed models were used to explore three aims: 1) changes in inflammatory biomarker levels between treatment groups at the primary 8-week endpoint; 2) changes in inflammatory biomarkers from baseline to study endpoint for those in the waitlist phase of the waitlist group and those in the yoga phase of the waitlist group; and 3) the interaction between baseline inflammatory biomarkers and change in depression severity after 8-weeks of heated yoga vs. waitlist control. ResultsForty-five participants (n = 17 for the heated yoga group and n = 28 for the waitlist group) had inflammatory biomarker data available for analyses. Significant differences in inflammatory biomarker levels were not found between groups at the 8-week endpoint (Aim 1). Similarly, changes in inflammatory biomarkers from baseline to study endpoint did not differ for those in the waitlist phase of the waitlist group and those in the yoga phase of the waitlist group (Aim 2). Lastly, the interaction between baseline inflammatory biomarkers and change in depression severity after 8-weeks of heated yoga vs. waitlist control was not significant (Aim 3). ConclusionHeated yoga showed no significant reduction in inflammatory biomarker levels. Possible reasons include a small sample size, insufficient heated yoga dosage, timing of sampling, not targeting individuals with higher baseline inflammatory biomarker levels, or peripheral inflammatory biomarkers not influencing heated yoga’s antidepressant effects. Further research is needed to clarify the antidepressant mechanisms of heated yoga.