Neurophysiological Signatures of Mindfulness-Based Stress Reduction in Adults with Autism: Putative Mechanism of Anxiety Alleviation

Objectives: Mindfulness-based therapies can reduce depression and anxiety in adults with autism spectrum disorder (ASD). However, the underlying neurophysiological mechanisms have yet to be fully characterized. While mindfulness-related improvements are theorized to be derived from alterations to resting-state networks—especially within the default mode network (DMN)—in other clinical populations, it is unclear if changes in DMN neurophysiology relate to symptom reduction in autistic adults. Method: In this randomized controlled trial, 96 adults with ASD were assigned to either a Mindfulness-Based Stress Reduction (MBSR) or a social support and relaxation education (SE) active control group. Resting-state electroencephalography recordings and self-report questionnaires assessing depression (BDI-2) and trait anxiety (STAI-2) were collected before and after the 8-week intervention to examine neurophysiological correlates of DMN activity—namely, gamma and high beta (beta-2) power across midline electrodes. Results: Spectral power analysis of neurophysiological signatures of DMN activity from 62 participants (MBSR n=29; SE n=33) identified distinct MBSR-induced reductions in frontal and parietal gamma power and frontal beta-2 power relative to the SE group. Both MBSR and SE groups showed reductions in central beta-2 and gamma-band power, suggestive of an overlapping mechanism. MBSR-specific decreases in parietal gamma power were associated with alleviation of anxiety symptoms. Conclusions: Findings suggest distinct neurophysiological correlates of mindfulness training implicating the DMN and point to a potential anxiolytic mechanism in adults with ASD. Preregistration: NCT04017793.