Lewy body disease is a contributor to logopenic progressive aphasia phenotype.

Objective To describe clinical features, [18 F]-fluorodeoxyglucose (FDG)-PET metabolism and digital pathology in patients with logopenic progressive aphasia and pathologic diagnosis of diffuse Lewy body disease (LPA-DLBD) and compare to LPA patients with other pathologies, as well as patients with classical features of probable dementia with Lewy bodies (pDLB). Methods This is a clinico-pathologic case-control study of 45 patients, including 20 prospectively recruited LPA patients among whom six with LPA-DLBD. We analyze clinical features and compare FDG-PET metabolism in LPA-DLBD to an independent group of clinical pDLB patients and regional α-synuclein burden on digital pathology to a second independent group of autopsied patients with DLBD pathology and ante mortem pDLB (DLB-DLBD). Results All LPA-DLBD patients were men. Neurological, speech and neuropsychological characteristics were similar across LPA-DLBD, LPA-Alzheimer disease (LPA-AD) and LPA- frontotemporal lobar degeneration (LPA-FTLD). Genetic screening of AD, DLBD and FTLD linked genes were negative. Seventy-five percent of LPA-DLBD patients showed a parietal-dominant pattern of hypometabolism; LPA-FTLD - temporal-dominant pattern whereas LPA-AD showed heterogeneous patterns of hypometabolism. LPA-DLBD had more asymmetrical hypometabolism affecting frontal lobes, with relatively spared occipital lobe in the non-dominantly affected hemisphere, compared to pDLB. LPA-DLBD had minimal atrophy on gross brain examination, higher cortical Lewy body counts and higher α-synuclein burden in middle frontal and inferior parietal cortices compared to DLB-DLBD. Interpretation Whereas AD is the most frequent underlying pathology of LPA, DLBD can also be present and may contribute to the LPA phenotype possibly due to α-synuclein-associated functional impairment of the dominant parietal lobe. This article is protected by copyright. All rights reserved.