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Lookup NU author(s): Daniel Collerton, Professor John-Paul TaylorORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© The Author(s) 2025. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center.BACKGROUND AND HYPOTHESIS: Visual hallucinations (VH) are a core symptom of both Lewy body diseases (LBDs; eg, Parkinson's disease and dementia with Lewy bodies) and serotonergic psychedelics (SPs; eg, psilocybin and mescaline). While these conditions differ in etiology, overlapping phenomenology, and neural mechanisms suggest shared pathways. This review explores similarities and differences in VH between LBDs and SPs, focusing on phenomenology, cortical function, and serotonergic modulation. STUDY DESIGN: This narrative review synthesizes findings from neurology, cognitive neuroscience, and systems neuroscience to compare VH in LBDs and SPs. The literature includes studies with both human subjects and animal models that examine cortical activity patterns, neuromodulatory mechanisms, and VH phenomenology. STUDY RESULTS: Both LBDs and SPs exhibit distinct visual aberrations, ranging from minor metamorphopsias to complex hallucinations. Some features in LBDs resemble those induced by SPs (eg, illusory motion and entity encounters), suggesting shared neural mechanisms. Neuroimaging studies indicate a common pattern of hyperactive associative cortex and hypoactive sensory cortex. At the neuromodulator level, SP-induced VH involves serotonin 2A and 1A receptor (5-HT2AR and 5-HT1AR) modulation, while in LBDs, 5-HT2A receptor upregulation correlates with increased VH, and its inhibition (eg, with pimavanserin) reduces VH. Two shared cortical signatures are highlighted: reduced visual evoked responses and shifts toward visual excitation. CONCLUSIONS: Examining cortical and neuromodulatory similarities between LBD- and SP-induced VH may elucidate the link between sensory degradation, excitation, and hallucinogenesis. Future research should employ real-time neuroimaging of discrete hallucinatory episodes to identify shared mechanisms and develop targeted interventions for LBD hallucinations.
Author(s): Heller NH, Barrett FS, Buchborn T, Collerton D, Dupuis D, Halberstadt AL, Jardri R, Noorani T, Preller KH, Taylor J-P, Waters F, Winston BS, Leptourgos P
Publication type: Review
Publication status: Published
Journal: Schizophrenia Bulletin
Year: 2025
Volume: 51
Issue: Suppl. 3
Pages: S273-S291
Print publication date: 01/10/2025
Online publication date: 06/10/2025
Acceptance date: 02/04/2025
ISSN (print): 0586-7614
ISSN (electronic): 1745-1701
URL: https://doi.org/10.1093/schbul/sbaf068
DOI: 10.1093/schbul/sbaf068
PubMed id: 41051875
