The Functional Connectivity of Hallucinations in Psychiatric Disorders and Neurodegenerative Disorders: A Systematic Review
Abstract
Background: Hallucinations span psychiatric and neurodegenerative disorders, yet unified neurobiological or consciousness-based explanations remain uncertain. Functional connectivity (FC) provides a network-level view with highly heterogeneous findings. Methods: Following PRISMA, we included studies with FC of hallucinations to ask whether it is sensitive to hallucinations, can distinguish different disorders, and if adopted theories are explanatory. Results: 198 studies were included, with far fewer studies in neurodegenerative (35) than psychiatric disorders (163). Across conditions, hallucinations consistently involved dysconnectivity among default mode (DMN), salience (SN), central executive (CEN), sensory systems, and subcortical circuits. Shared alterations included disrupted SN modulation of sensory gating, altered DMN-sensory coupling and within DMN coherence, limbic system involvement, and reduced CEN regulation of perceptual networks. Disorder‑specific patterns were evident: psychiatric hallucinations preferentially involved auditory-language networks, cortico‑striatal circuits, and salience hubs, whereas neurodegenerative hallucinations were characterised by visual and attentional network dysfunction, including dorsal and ventral attention systems and visual cortices. Conclusions: FC is sensitive to hallucinations and shows different disorder-linked patterns while revealing shared mechanisms, supporting the transdiagnostic nature of hallucinations at the level of functional brain networks. Despite the involvement of multiple transdiagnostic networks, the current literature does not converge on a unified cognitive or consciousness-based theory of hallucinations, underscoring a critical theoretical gap and the need for integrative models.
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BibTeX
@misc{ren2026functional,
title = {{The Functional Connectivity of Hallucinations in Psychiatric Disorders and Neurodegenerative Disorders: A Systematic Review}},
author = {Yifan Ren and Huyen N. Pham and Xiong Xiong and Shun-Chin Jim Wu and Emilio Fernandez-Egea and John T. O’Brien and Graham Murray and John suckling},
howpublished = {PsyArXiv},
year = {2026},
month = sep,
doi = {10.31234/osf.io/dt7gn_v1},
url = {https://osf.io/preprints/psyarxiv/dt7gn_v1/},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The Functional Connectivity of Hallucinations in Psychiatric Disorders and Neurodegenerative Disorders: A Systematic Review
AU - Yifan Ren
AU - Huyen N. Pham
AU - Xiong Xiong
AU - Shun-Chin Jim Wu
AU - Emilio Fernandez-Egea
AU - John T. O’Brien
AU - Graham Murray
AU - John suckling
PY - 2026
DA - 2026/09/16
PB - PsyArXiv
DO - 10.31234/osf.io/dt7gn_v1
UR - https://osf.io/preprints/psyarxiv/dt7gn_v1/
AB - Background: Hallucinations span psychiatric and neurodegenerative disorders, yet unified neurobiological or consciousness-based explanations remain uncertain. Functional connectivity (FC) provides a network-level view with highly heterogeneous findings. Methods: Following PRISMA, we included studies with FC of hallucinations to ask whether it is sensitive to hallucinations, can distinguish different disorders, and if adopted theories are explanatory. Results: 198 studies were included, with far fewer studies in neurodegenerative (35) than psychiatric disorders (163). Across conditions, hallucinations consistently involved dysconnectivity among default mode (DMN), salience (SN), central executive (CEN), sensory systems, and subcortical circuits. Shared alterations included disrupted SN modulation of sensory gating, altered DMN-sensory coupling and within DMN coherence, limbic system involvement, and reduced CEN regulation of perceptual networks. Disorder‑specific patterns were evident: psychiatric hallucinations preferentially involved auditory-language networks, cortico‑striatal circuits, and salience hubs, whereas neurodegenerative hallucinations were characterised by visual and attentional network dysfunction, including dorsal and ventral attention systems and visual cortices. Conclusions: FC is sensitive to hallucinations and shows different disorder-linked patterns while revealing shared mechanisms, supporting the transdiagnostic nature of hallucinations at the level of functional brain networks. Despite the involvement of multiple transdiagnostic networks, the current literature does not converge on a unified cognitive or consciousness-based theory of hallucinations, underscoring a critical theoretical gap and the need for integrative models.
ER -