White matter abnormalities of right hemisphere attention networks contribute to visual hallucinations in dementia with Lewy bodies

Giovanni Zorzi; Michel Thiebaut de Schotten; Renzo Manara; Cinzia Bussè; Maurizio Corbetta; Annachiara Cagnin

doi:10.1016/j.cortex.2021.03.007

White matter abnormalities of right hemisphere attention networks contribute to visual hallucinations in dementia with Lewy bodies

Cortex. 2021 Jun:139:86-98. doi: 10.1016/j.cortex.2021.03.007. Epub 2021 Mar 18.

Authors

Giovanni Zorzi¹, Michel Thiebaut de Schotten², Renzo Manara³, Cinzia Bussè⁴, Maurizio Corbetta⁵, Annachiara Cagnin³

Affiliations

¹ Department of Neuroscience, University of Padova, Padova, Italy; Padova Neuroscience Center, University of Padova, Padova, Italy. Electronic address: giovanni.zorzi.2@phd.unipd.it.
² Padova Neuroscience Center, University of Padova, Padova, Italy; Brain Connectivity and Behaviour Laboratory, Sorbonne Universities, Paris, France; Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives-UMR 5293, CNRS, CEA University of Bordeaux, Bordeaux, France.
³ Department of Neuroscience, University of Padova, Padova, Italy; Padova Neuroscience Center, University of Padova, Padova, Italy.
⁴ Department of Neuroscience, University of Padova, Padova, Italy.
⁵ Department of Neuroscience, University of Padova, Padova, Italy; Padova Neuroscience Center, University of Padova, Padova, Italy; Department of Neurology, Radiology, Neuroscience, Washington University School of Medicine, St.Louis, MO, USA.

PMID: 33848693
DOI: 10.1016/j.cortex.2021.03.007

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.

Keywords: DTI; Dementia with Lewy bodies; MRI; Visual hallucination; White matter.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Brain
Hallucinations / diagnostic imaging
Humans
Lewy Body Disease* / complications
Lewy Body Disease* / diagnostic imaging
Neuropsychological Tests
White Matter* / diagnostic imaging