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

Objective This study had the objective to investigate the effect of regular contemplative mental training on endocrine indices of long-term stress. Methods An open-label efficacy trial comprising three distinct 3-month modules targeting attention and interoception, socio-affective or socio-cognitive abilities through dyadic exercises and secularised meditation practices was designed and carried out in 332 healthy meditation-naive adults. Participants underwent the training for up to 9 months or were assigned to a retest control cohort. Chronic stress indices were assayed at four timepoints, i.e., pre-training and following each module. The main outcome measures were cortisol and cortisone concentration in hair and self-reported chronic stress Results N=362 initial individuals were randomized, of whom n=30 dropped out before study initiation, n=4 before first sampling and n=2 were excluded. N=99 participants did not provide hair samples. Data from three separate training cohorts revealed consistent decreases in hair cortisol and cortisone levels over the training period. This effect increased with practice frequency, was independent of training content and not associated with change in self-reported chronic stress. Conclusions Our results point to the reduction of long-term cortisol exposure as a mechanism via which contemplative mental training may exert positive effects on practitioners’ health. Trial registration ClinicalTrials.gov identifier: NCT01833104