PRODROMAL AND NON-PRODROMAL DEMENTIA WITH LEWY BODIES AND ALZHEIMER'S DISEASE: A MULTIMODAL MRI APPROACH

Abstract

Dementia with Lewy bodies (DLB) is one of the main etiology of dementia after Alzheimer's disease (AD). Brain imaging studies have reported very few data in prodromal dementia with Lewy bodies (MCI-DLB). To focus on an earlier stage of the disease in a differential diagnostic perspective, we aimed to describe patterns of volume, perfusion, and connectivity in prodromal and non-prodromal DLB, and to assess for differences with prodromal and non-prodromal AD. We studied 112 subjects including 41 prodromal DLB patients, 15 DLB patients at the mild stage of dementia (mild-DLB), 14 prodromal AD (MCI-AD), 21 AD patients at the mild stage (mild-AD), and 21 healthy elderly controls (HC). They all underwent T1 3D MPRAGE, Asl (arterial spin labeling), and DTI MRI sequences. Voxel-wise analysis was conducted for grey matter and perfusion. The analysis of DTI consists in extending the general linear model, as implemented in SPM, to tensor images taking into account all information available in the tensor. Significant effects were identified by a correction for multiple comparisons using family-wise error and false discovery rate at p<0.05. MCI-DLB patients showed diminished GM volumes of bilateral insulae, mild-DLB patients of bilateral insulae, claustrum and putamen, MCI-AD patients of hippocampus and parahippocampal gyrus (right predominant), and mild-AD patients of temporal lobes including hippocampi. The areas of hypoperfusion were larger than atrophy, including anterior cingulate and insular areas for MCI-DLB. The areas of modifications of the tensor images included insulae, anterior cingulate and frontal regions in MCI-DLB. Using three different MRI approach, we found in all cases modifications of the insulae in DLB patients, at the stage of MCI but also mild dementia. Our results supplement previous reports by describing these early abnormalities and supports the role of insula in DLB at the early stages. Moreover it seems that focal atrophy in insula has distant consequences in MCI-DLB patients as seen in perfusion, and is the reflect of probable more diffuse lesions according to the tensor images. The next step is to better understand what is the link of these results with symptoms of DLB such as hallucinations, fluctuations, cognition, and neurovegetative symptoms.