Dynamic Repertoire of Brain Networks in Mindfulness-Based Cognitive Therapy During Rumination: A Randomized Controlled Trial

BACKGROUND Depression is a prevalent and debilitating affective disorder characterised by the dominance and persistence of depressive rumination. Mindfulness-based cognitive therapy (MBCT) is an effective treatment for recurrent depression developed specifically to target rumination and recurrence risk by training metacognitive awareness and adaptive attention, emotion and self-regulation skills. Yet, the underlying mechanisms by which mindfulness training impacts maladaptive depressive rumination is not well understood, and a deeper understanding of its effects on the complex brain dynamics during depressive rumination is needed. METHODS In a randomised controlled functional magnetic resonance imaging (fMRI) study (N = 80), we examined dynamic neural changes during resting state fMRI of an experimentally induced rumination state before and after treatment with MBCT (N = 27) for recurrent depression in addition to treatment as usual (TAU) or TAU alone (N = 21). More specifically, we characterized the changes during a depressive rumination-state as a repertoire of metastable substate each with an occurrence frequency (Fractional Occupancy) and stability (Lifetimes). RESULTS We found that MBCT training compared with TAU altered the Fractional Occupancy of a ‘salience-somatomotor’ metastable substate during the depressive rumination state. These dynamic network changes in turn were associated with reduced trait rumination post treatment and reduced depressive symptoms at three months follow up. CONCLUSION In a ruminative-state, changes in the dynamics of the somatosensory-salience network following mindfulness training was associated with improved clinical outcomes and reduced trait rumination, which may provide insight into candidate brain mechanisms or markers of treatment response to MBCT.