ABSTRACT Dementia with Lewy bodies (DLB) is one of the most common causes of degenerative dementia after Alzheimer’s disease (AD) and presents pathological and clinical overlap with both AD and Parkinson’s disease (PD). Consequently, only one in three DLB cases is diagnosed correctly. Platelets, previously related to neurodegeneration, contain microRNAs (miRNAs) whose analysis may provide disease biomarkers. Here, we profiled the whole platelet miRNA transcriptome from DLB patients and healthy controls. Differentially expressed miRNAs were further validated in three consecutive studies from 2017 to 2019 enrolling 162 individuals, including DLB, AD, and PD patients, and healthy controls. Results comprised a 7-miRNA biosignature, showing the highest diagnostic potential for the differentiation between DLB and AD. Additionally, compared to controls, two miRNAs were down-regulated in DLB, four miRNAs were up-regulated in AD, and two miRNAs were down-regulated in PD. Predictive target analysis identified three disease-specific clusters of pathways as a result of platelet-miRNA deregulation. Our cross-sectional study assesses the identification of a novel, highly specific and sensitive platelet-associated miRNA-based bio-signature, which distinguishes DLB from AD. The paper explained Problem Dementia with Lewy bodies (DLB) presents pathological and clinical overlap with both Alzheimer’s (AD) and Parkinson’s disease (PD), which impairs its correct diagnosis. Although numerous papers report peripheral biomarkers for AD, well-established biomarkers for DLB distinguishing it from AD are still missing. Platelet miRNA transcriptome was analyzed in several works, but their putative role as disease biomarkers for neurological disorders has not been assessed. It would be of paramount importance to establish a blood-based bio-signature as a minimally invasive mean for DLB diagnosis, improving differentiation of DLB patients from controls and AD. Results Our study revealed that platelet miRNAs might be promising biomarkers for the correct diagnosis of DLB stratifying patients in comparison with overlapping disorders, especially AD, and may help to highlight possible disease-related processes. In this cross-sectional study, which includes 162 individuals (DLB, AD, PD and healthy controls), platelet-associated miRNA content was disease group-specific. Three different miRNA sets together with their predicted targeted pathways were defined. Impact This study suggests that platelet miRNA may serve as DLB biomarker allowing the correct diagnosis and stratification in an easily-applied manner in clinical settings, and may help to highlight possible disease-related processes.

Platelet miRNA bio-signature discriminates between dementia with Lewy bodies and Alzheimer disease