Neural correlates of neurovisual deficits in prodromal and mild dementia with Lewy bodies: A voxel-based morphometry study

BackgroundDementia with Lewy bodies (DLB) is one of the main degenerative dementias after Alzheimer's disease and is characterized by neurovisual deficits. Volumetric MRI data on these deficits and their neuro-anatomical correlates are lacking.ObjectiveWe propose a volumetric analysis of the neuro-anatomical substrates of neurovisual deficits in DLB, as assessed by subtests of the Visual Object and Space Perception (VOSP) battery and the Rey-Osterrieth Complex Figure (ROCF).MethodsSeventy patients with prodromal to mild DLB were included in the study, along with 23 healthy elderly subjects (NCT01876459). We used VOSP's incomplete letters (LET) for object perception, and dot counting (DOT) for space perception. The ROCF copy was used to assess visuoconstruction. Correlation analyses were performed in voxel-based morphometry (VBM).ResultsVBM analyses showed a positive correlation between LET performance and the left cerebellar hemisphere (p < 0.05, family-wise error). Positive correlations between LET performance and bilateral occipitotemporal cortex were also demonstrated (p < 0.001 uncorrected). VBM analyses showed a positive correlation between DOT performance and both occipitoparietal cortex and cerebellum (p < 0.001 uncorrected). ROCF performance was positively correlated with frontoparietal cortex (p < 0.001 uncorrected).ConclusionsVisuoperceptive performance (i.e., on LET) was associated with the occipitotemporal cortex, corresponding to the "what" pathway, while performance involving visuospatial skills (i.e., on DOT and ROCF) was associated with the occipitoparietal cortex, corresponding to the "where" pathway. The cerebellum also appears to be involved, predominantly in visuoperception (LET). This exploratory work suggests the involvement of the cerebellum in the neurovisual impairment of DLB, alongside other regions classically involved in visuoperception.