Dynamical repertoire of brain networks in mindfulness cognitive behavioural 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. METHOD: In a randomised controlled functional magnetic resonance imaging (fMRI) study (N = 80), we used LEiDA (Leading Eigenvector Dynamics Analysis) to determine the key substates 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). We determined the probability of occurrence (fractional occupancy) and the duration (lifetime) of underlying substates (phase-locking patterns) before and after treatment for both groups. RESULTS: We found that MBCT training compared with TAU altered the fractional occupancy of a 'Salience-somatomotor' substate during the depressive rumination induction. These dynamic network changes in turn were associated with reduced depressive symptoms after treatment and at three months follow up. CONCLUSION: In a depressive ruminative state, changes in the dynamics of the somatosensory-salience network following mindfulness training was associated with improved clinical outcomes which provides insight into candidate brain mechanisms or markers of treatment response.