The Neuroscience of Religious and Spiritual Practices: A Systematic Review of Neurotheological Evidence.

BACKGROUND: Religious and spiritual practices are among the most ancient and universal human behaviors, yet their neurobiological substrates remain incompletely characterized. Neurotheology-the scientific study of the relationship between spiritual experience and brain function-has produced growing evidence that such practices generate measurable, systematic, and neuroplastic changes in brain structure and function. However, prior reviews have been limited to single practice types, narrow evidence bases, or narrative methods, with none synthesizing the full spectrum of traditions, practices, and neuroimaging modalities in a single review. METHODS: Adhering to the PRISMA 2020 guidelines and registered on the Open Science Framework, Scopus, PubMed/MEDLINE, and ProQuest (23 sub-databases) were searched from inception to June 30, 2026. Eligible studies comprised those using objective neuroimaging or neurophysiological techniques. After multi-stage screening, 105 studies (1998-2026) were synthesized narratively using the synthesis without meta-analysis (SWiM) framework, given substantial heterogeneity. RESULTS: Studies spanned Buddhist, Christian, Islamic, Hindu, Santo Daime, Spiritist, Sant Mat, and mixed traditions, examining meditation, prayer, chanting, recitation, worship, retreat, mystical experience, mediumistic trance, and ritual altered states. Consistent engagement appeared across the prefrontal cortex, anterior cingulate, default mode network (DMN), insula, amygdala, hippocampus, temporoparietal junction, and dopaminergic/serotonergic systems. Practice-specific signatures emerged: meditation (DMN suppression, prefrontal augmentation), prayer (social-cognition networks), chanting/recitation (limbic deactivation, gamma/delta enhancement), and mystical states (most distributed profiles). Long-term practitioners showed structural neuroplasticity, and clinical-population studies linked these circuits to depression, anxiety, and stress. CONCLUSIONS: Religious and spiritual practices produce consistent, practice-specific, and neuroplastic modifications to brain systems governing attention, emotion regulation, self-referential processing, and reward-supporting a plausible mechanistic link between spiritual engagement and mental health, and positioning neurotheology as an empirically grounded dialogue between contemplative tradition and clinical neuroscience.