Researchers of this two-cohort resting-state fMRI study probed functional-connectivity (FC) markers of visual hallucinations (VH) in Parkinson’s disease (PD). In the discovery cohort (Parkinson’s Progression Marker Initiative [PPMI]: 25 PD with VH [PDVH], 56 without [PDNOVH], 24 healthy controls), investigators compared global FC and FC within Yeo networks and von Economo classes. Replication used the Incidence of Cognitive Impairment in Cohorts with Longitudinal Evaluation-PD cohort (104 patients; NEVHI for VH classification/severity).
Global FC and most network-level differences were nonsignificant after FDR correction, except for limbic network reductions in PD versus controls. Network-based statistics identified a subnetwork of reduced FC in PDVH spanning dorsal and ventral attention networks, default mode, and somatomotor regions. Lower FC within this subnetwork replicated in ICICLE-PD (masked mean FC) and correlated with hallucination severity. In PPMI, higher subnetwork FC related to better attention/executive/global cognition (trend in PDVH) and predicted better future attention and Montreal Cognitive Assessment. Lower baseline FC predicted worse future motor severity. No analogous longitudinal links appeared in PDNOVH. Findings support a targeted attentional-DMN dysconnectivity signature for VH in early PD and motivate network-informed interventions.
Reference: Montagnese M, Mehta MA, Ffytche D, et al. Disrupted functional brain network associated with presence of hallucinations in Parkinson’s disease. Brain Commun. 2025;7(3):fcaf185. doi: 10.1093/braincomms/fcaf185.
