Neural and autonomic regulation during brief mindfulness and relaxation interventions in clinical populations: a multimodal MEG study protocol

Mental disorders pose a major and growing challenge for health care systems worldwide, marked by persistent treatment gaps and limited access to psychotherapeutic care. Mind–body interventions such as mindfulness and relaxation practices are widely used in clinical contexts as low-threshold strategies to support stress regulation and psychological well-being. Despite their broad application, the mechanisms underlying their acute effects remain insufficiently understood, particularly regarding brain–body interactions. This study protocol describes a prospective multimodal investigation of regulation during brief mindfulness-and relaxation-based interventions in clinical populations (at least n = 15 adults with depression according to SCID-5-CV and at least n = 15 adults with adult ADHD according to SCID-5-CV). Using a standardized within-subject experimental paradigm, magnetoencephalography (MEG) will be combined with electrocardiography (ECG) and respiratory measures to capture fast neural dynamics and autonomic regulation during three randomized auditory conditions: mindfulness (body scan), relaxation (safe place imagery), and an auditory control condition (podcast). Subjective ratings of stress and relaxation will be collected repeatedly across the procedure, complemented by questionnaires characterizing interindividual differences relevant to regulation. Outcome measures will include indices of autonomic regulation derived from cardiac activity and respiration, as well as repeated subjective ratings of stress and relaxation across conditions. Neural measures (MEG) will be used to characterize condition-related brain dynamics and brain–body coupling metrics linking neural oscillations to cardiac and respiratory rhythms. Speech-related measures during auditory guidance and brief speech-production features from post-condition reflections will be included as complementary and exploratory extensions to increase psychotherapy relevance, while accounting for methodological challenges related to overt speech in MEG. By integrating neural, physiological, and subjective measures within a single standardized paradigm, this study protocol aims to advance a mechanistic understanding of brief mind–body interventions in clinically relevant populations. Focusing on dynamic brain– body interactions during stress and regulation, the proposed approach is designed to support transparent and reproducible investigation of regulatory processes that are relevant to psychotherapy-related mind–body approaches, clinical practice, and everyday self-regulation. The findings are expected to inform future translational research and contribute to the development of mechanism-informed and potentially personalized applications of mindfulness-and relaxation-based interventions. Study protocol registration Preregistration can be found here: https://osf.io/3rhk4/overview .