Language impairment in Lewy body Disease: A systematic review

Introduction: Dementia with Lewy bodies (DLB) is the second leading cause of cognitive impairments in neurodegenerative disorders. Although language disorders are not part of the current diagnostic criteria for DLB, their presence is frequently observed in this condition. There are only a few studies specifically focusing on language disorders in DLB. Method: The aim of this article is to carry out a systematic review focusing on language disorders in DLB, following the PRISMA method. Results: Out of 863 articles, 22 have been included in this literature review. Verbal fluency and naming tests are more impaired in DLB compared to Parkinson's patients or healthy subjects. The co-pathology involving Alzheimer's disease and DLB appears to exacerbate language disorders. DLB patients also have difficulties structuring their speech, which may contribute to difficulties in expression or comprehension. Finally, exceptionally, DLB can present as logopenic variant of primary progressive aphasia. Conclusion: This original systematic review highlights the limited number of studies carried out in this field of research and the significant heterogeneity of the tools used to evaluate language in DLB. A standardized systematic exploration of language in DLB would lead to a better understanding of these disorders.