Blood mRNA Expression in Alzheimer's Disease and Dementia With Lewy Bodies

•What is the primary question addressed by this study?We investigated whether changes in gene expression in blood were present in Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) compared with controls using ribonucleic acid sequencing.•What is the main finding of this study?Differentially expressed genes were identified in both diseases and ANP32A was associated with more rapid cognitive decline in AD. Gene sets related to mitochondrial function were downregulated in DLB and gene sets related to inflammation and immune function were upregulated in AD.•What is the meaning of the finding?Ribonucleic acid sequencing of blood demonstrates altered gene expression in key physiological pathways in DLB and AD, and highlights differences in inflammatory and immune responses between the diseases.