White matter abnormalities of right hemisphere attention networks contribute to visual hallucinations in dementia with Lewy bodies. (June 2021)

• Record Type: Journal Article
• Authors: Zorzi, Giovanni; Thiebaut de Schotten, Michel; Manara, Renzo; Bussè, Cinzia; Corbetta, Maurizio; Cagnin, Annachiara
• Is Part Of: Cortex. Volume 139(2021)
• Page Start: 86
• Page End: 98
• Publication Date: 2021-06
• Subjects: Dementia with Lewy bodies -- Visual hallucination -- DTI -- MRI -- White matter; Neuropsychology -- Periodicals; Nervous system -- Periodicals; Neurology -- Periodicals; Psychophysiology -- Periodicals; Behavior -- Periodicals; Neurology -- Periodicals; 612.825
• DOI: 10.1016/j.cortex.2021.03.007
• Languages: English
• ISSNs: 0010-9452

Abstract

Abstract: Objective: Functional alterations of the visual attention networks in a setting of impaired visual information processing have a role in the genesis of visual hallucinations (VH) in dementia with Lewy bodies (DLB). This multimodal MRI study aims at exploring structural and functional basis of VH. Methods: 23 DLB patients (10 with and 13 without VH) and 13 healthy controls were studied. They underwent MRI with T1-w sequences to measure cortical thickness, DTI for whole-brain and single tract microstructural properties and rs-fMRI of the default mode, dorsal and ventral attention, and visual networks. Results: In DLB with VH, whole-brain DTI revealed a lower fractional anisotropy and a greater mean diffusivity in the right frontal and temporo-parietal white matter tracts. Tracts dissection showed lower fractional anisotropy in the right inferior and superior (ventral part) longitudinal fasciculi (ILF and SLF) ( p < .05, corrected), and greater mean diffusivity ( p < .05). The extent of white matter microstructural alterations involving the right ILF and SLF correlated with the severity of VH ( r = .55, p < .01; r = .42, p < .05, respectively), and with performance in the visual attention task ( r = −.56 and r = −.61; p < .01, respectively). Cortical thickness in the projection areas of the right SLF was significantly reduced ( p < .05). Patients with VH also showed an altered functional connectivity in the ventral attention network, connected by the ventral portion of the SLF ( p < .05). Conclusions: Our findings suggest that a combination of microstructural and functional alterations involving the attention networks in the right hemisphere may be important in the genesis of VH.