It has long been promoted that after a few weeks of training in a mindfulness-based stress reduction (MBSR) program, one of the many benifits includes actual changes in brain structure. This is known as known as neuroplasticity.
Specifically, prior studies claimed that over an 8 week period participants of MBSR “had increased gray matter density (GMD) in the hippocampus, posterior cingulate cortex (PCC), temporoparietal junction (TPJ), cerebellum, and brainstem and increased gray matter volume (GMV) in the left caudate” (Kral 2022).
In short, the meditaion practice was increasing functional brain volume.
Now, in the largest and most rigorously controlled study to date, researchers failed to replicate previous claims and have found no evidence that MBSR produces neuroplastic changes in the brain.
It is important to note here that the study only looked at the MBSR program and only over 8 weeks. Other published studies support structural changes in long-term meditators using alternative practice modalities.
The authors of this study conclude:
…it is important for future research to examine individual differences in engagement and efficacy of MBSR, as well as the optimum length and duration of daily practice for a mindfulness meditation intervention to confer benefits. The lack of significant group differences between MBSR and control groups in the current study suggests that interventions lasting longer than the standard 8-week MBSR course and/or singularly focused on one specific meditation practice might be required to produce changes in brain structure.
Link to full study: https://doi.org/10.1126/sciadv.abk3316