Contemplative Mental Training Reduces Hair Glucocorticoid Levels in a Randomized Clinical Trial

Lara M C Puhlmann, Pascal Vrtička, Roman Linz, Tobias Stalder, Clemens Kirschbaum, Veronika Engert, Tania Singer, Lara M C Puhlmann, Pascal Vrtička, Roman Linz, Tobias Stalder, Clemens Kirschbaum, Veronika Engert, Tania Singer

Abstract

Objective: This study aimed to investigate the effect of regular contemplative mental training on endocrine and psychological indices of long-term stress.

Methods: An open-label efficacy trial that comprised three distinct 3-month long modules targeting attention and interoception, socioaffective, or sociocognitive abilities through dyadic exercises and secularized meditation practices was conducted with healthy adults. Participants underwent the training for 3 or 9 months, or were assigned to a retest control cohort. Chronic stress indices were assayed at four time points: pretraining and after 3, 6, and 9 months. The main outcome measures were cortisol (HC) and cortisone (HE) concentration in hair and self-reported long-term stress.

Results: Of 362 initially randomized individuals, 30 dropped out before study initiation (n = 332; mean [SD] age = 40.7 [9.2] years; 197 women). Hair-based glucocorticoid assays were available from n = 227, and questionnaire data from n = 326. Results from three separate training cohorts (TC1-3) revealed consistent decreases in HC and HE levels over the first three (TC3) to 6 months (TC1 and TC2) of training, with no further reduction at the final 9-month mark (baseline to end of training differences, HC, TC1: t(355) = 2.59, p = .010, contrast estimate (est.) [SE] = 0.35 [0.14]; HC, TC2: t(363) = 4.06, p < .001, est. = 0.48 [0.12]; HC, TC3: t(368) = 3.18, p = .002, est. = 0.41 [0.13]; HE, TC1: t(435) = 3.23, p = .001, est. = 0.45 [0.14]; HE, TC2: t(442) = 2.60, p = .010, est. = 0.33 [0.13]; HE, TC3: t(446) = 4.18, p < .001, est. = 0.57 [0.14]). Training effects on HC increased with individual compliance (practice frequency), and effects on both HC and HE were independent of training content and unrelated to change in self-reported chronic stress. Self-reported stress, and cortisol-to-dehydroepiandrosterone ratios as an exploratory endpoint, were also reduced, albeit less consistently.

Conclusions: Our results point to the reduction of long-term cortisol exposure as a mechanism through which meditation-based mental training may exert positive effects on practitioners' health.Trial Registration: ClinicalTrials.gov identifier: NCT01833104.

Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Psychosomatic Society.

Figures

FIGURE 1
FIGURE 1
Study protocol and design. A, Core processes and practices of the ReSource training. The Presence module aims to train attention and interoceptive body awareness; its two core practices are breathing meditation and body scan. The Affect module targets social emotions such as compassion, loving kindness, and gratitude; core practices are loving-kindness meditation and the Affect dyad. In the Perspective module, metacognition and perspective taking on the self and others are trained through the core practices observing-thoughts meditation and Perspective dyad. B, Design and timeline of the Resource Project. Two training cohorts, TC1 and TC2, started their training with the mindful attention–based Presence module. They then underwent the social Affect and Perspective modules in different orders. The total training time for TC1 and TC2 was 39 weeks (13 weeks per module). TC3 only trained the Affect module for 13 weeks and the two RCC underwent all testing but no training (for more detailed information, see (42,43)). Figure reproduced and adapted from (8,44). RCC = retest control cohort; TC1–3, training cohorts 1–3. Color image is available online only at www.psychosomaticmedicine.org.
FIGURE 2
FIGURE 2
Participant flowchart for the analysis of HC and HE. This figure combines numbers from two recruitment periods in 2012/2013 and 2013/2014. Adapted from (8). Further details on the sex distribution in dropouts and final analysis samples are shown in the Supplemental Material, Table S2, http://links.lww.com/PSYMED/A759. HC = hair cortisol; HE = hair cortisone; fMRI = functional magnetic resonance imaging; SCID = Structural Clinical Interview for DSM-IV Disorders (Axis I and Axis II); RCC = retest control cohort; TC = training cohort. a) Reasons for no hair sampling throughout were baldness or opting-out.
FIGURE 3
FIGURE 3
Training effects on HC and HE. Estimated HC (A) and HE (B) levels were derived from the linear mixed-model analysis as a function of training cohort and time point. Note the natural log scale on the y-axis. Error bars represent ±1 SE; each circle represents one raw data point with outliers winsorized as described in the Methods section. Asterisks below bars indicate comparison with the RCC at the matched time point. *Significant at p ≤ .05. **Significant at p ≤ .01. ***Significant at p ≤ .001. See Tables S5 and S6, http://links.lww.com/PSYMED/A759 for a full list of contrast outcomes. HC = hair cortisol; HE, hair cortisone; SE, standard error; RCC, retest control cohort; TC, training cohort. Color image is available online only at www.psychosomaticmedicine.org.
FIGURE 4
FIGURE 4
Training effects on HC and HE in baseline-matched analysis. Estimated HC (A) and HE (B) levels were derived from LMM analysis in a sample of participants with matched baseline HC and HE levels across cohorts, generated based on the study participant pool. Participants from each TC were matched to RCC participants with replacement depending on their baseline glucocorticoid levels and sex. Note the natural log scale on the y-axis. Error bars represent ±1 SE. Asterisks below bars indicate comparison with RCC at the matched time point. *Significant at p ≤ .05. **Significant at p ≤ .01. ***Significant at p ≤ .001. HC = hair cortisol; HE = hair cortisone; SE = standard error; RCC = retest control cohort; TC = training cohort. Color image is available online only at www.psychosomaticmedicine.org.
FIGURE 5
FIGURE 5
Training effects on HC/DHEA ratios in hair. Estimated HC/DHEA ratios were derived from the linear mixed-model analysis as a function of training cohort and time point. Note the natural log scale on the y-axis. Error bars represent ±1 SE; each circle represents one raw data point with outliers winsorized as described in the Methods section. Asterisks below bars indicate comparison with RCC at the matched time point. *Significant at p ≤ .05. **Significant at p ≤ .01. ***Significant at p ≤ .001. See Supplemental Material, Table S7, http://links.lww.com/PSYMED/A759 for a full list of contrast outcomes. HC = hair cortisol; DHEA = dehydroepiandrosterone; SE = standard error; RCC = retest control cohort; TC = training cohort. Color image is available online only at www.psychosomaticmedicine.org.
FIGURE 6
FIGURE 6
Training effects on self-reported long-term stress. Estimated scores of (A) Perceived Stress Scale (PSS; (28)) and (B) Trier Inventory for Chronic Stress (TICS; (29)) derived from the linear mixed-model analysis as a function of training cohort and time point. Error bars represent ±1 SE; each circle represents one data point. *Significant at p ≤ .05. **Significant at p ≤ .01. ***Significant at p ≤ .001. Color image is available online only at www.psychosomaticmedicine.org.

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