Online Mindfulness-Based Cognitive Therapy (MBCT) is a promising intervention for mental health, but its effectiveness in reducing depressive symptoms remains underexplored. While key mechanisms of change have been identified in traditional MBCT, their role in online delivery formats needs further investigation. This study aimed to evaluate the effectiveness of synchronous and asynchronous online MBCT in reducing depressive symptoms and to examine potential mechanisms of change. In this randomized clinical trial, 170 individuals with mild to moderate depression were assigned to a 6-week synchronous online MBCT group (n = 58), asynchronous online MBCT group (n = 59), or waitlist control (n = 53). Depression, anxiety, mindfulness, cognitive fusion, rumination, self-compassion, resilience, and experiential avoidance were assessed at baseline, post-treatment, and 3-month follow-up. Posttest assessments were completed by 42 participants (72%) in the synchronous group, 32 (54%) in the asynchronous group, and 51 (96%) in the waitlist control condition. Both MBCT formats significantly reduced depressive symptoms compared to the control group, with sustained effects at follow-up. Mindfulness and cognitive defusion emerged as significant mediators, explaining 52% of the variance in the post-treatment depression severity. Additionally, participants in both interventions showed decreased rumination and anxiety, and increased self-compassion and resilience—effects maintained at follow-up. Both MBCT formats led to significant improvement in depression and related outcomes, with no significant differences detected between them. However, the study was not powered to test noninferiority, and these findings should be interpreted with caution. The synchronous format had lower attrition, suggesting that real-time interaction may enhance adherence. Either format can be used for mild to moderate depression, with the choice informed by expected engagement and available resources. This trial was preregistered at ClinicalTrials.gov (Identifier: NCT05919875).
Wardęszkiewicz et al. (Wed,) studied this question.