Is meditation associated with altered brain structure? A systematic review and meta-analysis of morphometric neuroimaging in meditation practitioners.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational morphometric neuroimaging studies
PubMed 24705269 · doi:10.1016/j.neubiorev.2014.03.016
What was done
The authors conducted a systematic review and anatomical likelihood estimation (ALE) meta-analysis of 123 brain morphology differences from 21 neuroimaging studies examining approximately 300 meditation practitioners. They also performed an effect size meta-analysis pooling 132 effect sizes from 16 of the studies.
What was found
ALE meta-analysis identified 8 brain regions consistently altered in meditators: frontopolar cortex (BA 10), sensory cortices, insula, hippocampus, anterior and mid-cingulate cortices, orbitofrontal cortex, superior longitudinal fasciculus, and corpus callosum. Effect size meta-analysis across 16 studies found a global medium effect size (mean Cohen's d = 0.46; mean r = 0.19).
Why it matters
It provides a consolidated quantitative estimate of structural brain differences associated with meditation practice, linking them to networks supporting awareness, emotion regulation, and memory consolidation.
Limits
The authors explicitly highlight strong concerns regarding publication bias and methodological limitations among the included studies. The overall sample size is relatively small (~300 practitioners across 21 studies), and cross-sectional or observational imaging cannot prove that meditation caused these morphological differences.