Three-months Transcendental Meditation reductions in perceived stress are associated with DMN increased connectivity at rest

Introduction: Meditation practices have been reported to favor psychological well-being and to affect brain functional and structural architecture. Here we combined psychometric assessment and resting state (RS-)fMRI to investigate whether and to what extent behavioral and brain changes may occur after the first 3-months of Transcendental Meditation (TM) practice in naïve subjects. Methods: After signing an informed consent, thirty-four healthy adults participated in the study: 19 subjects voluntarily chose to be part of the ‘meditation group’ (29±9y, 10F), while 15 subjects were included in the ‘control group’ (32±11y, 7F). The meditation group was instructed to complete two daily 20-min TM sessions, one in the morning and one in the evening. At recruitment (T0) and after 3 months (T1), all participants completed six questionnaires assessing anxiety, stress, depression, resilience and empathy, and underwent two MRI scans (1.5T), including ~7’30” RS-fMRI and high-resolution anatomical images. A Principal Component Analysis was applied to psychometric scores, and the first component (C1, 25% of total variance) was selected. Relative T1-T0 variations in C1 were assessed in each group using paired t-tests, while a Fisher’s exact test was applied to investigate between group differences. Analyses of fMRI data were performed using AFNI and FSL. In particular, potential T1-T0 changes in the Default Mode Network (DMN) were investigated using a seed-based functional connectivity analysis (NeuroSynth peak coordinates [0,-50,24]) and a linear-mixed effect model. Results: At T0 demographic variables and C1 score, which reflected an aggregate measure of anxiety, stress and depression, did not differ between groups. Meditation time was 30.6±12.8 hours (M±SD) in the 3-months period. At T1, the proportion of individuals showing a C1 (anxiety/stress) reduction was significantly different between the TM and control groups (79% vs. 40%, respectively, p=0.03; Fisher’s exact test). Indeed, a significant reduction in C1 score was observed in meditators (p=0.02) but not in controls (p=0.85). While no significant difference in DMN-connectivity between T0 and T1 was found in either group, meditators showed a significant negative correlation between C1 score variation and DMN-connectivity in precuneus and right parietal cortex (p<0.05, cluster-corrected, Fig.1). Conclusions: A relatively brief TM practice period was accompanied by a reduction in subjective anxiety, which in turn was significantly associated with a connectivity increase in the posterior portion of the DMN. These findings support the beneficial effect of TM on psychological well-being, and suggest a role for brain functional networks that comprise areas crucial for reappraisal and subjective relief.