Integrative Genetic and Transcriptomic Analysis Reveals Candidate Molecular Differences Among Dementia with Lewy Bodies, Alzheimer’s Disease, and Parkinson’s Disease Dementia

Dementia with Lewy bodies (DLB) shares substantial clinical and molecular features with Alzheimer’s disease (AD) and Parkinson’s disease dementia (PDD), complicating the identification of disease-specific molecular alterations. This study aimed to characterize transcriptomic differences among these disorders and to integrate expression findings with published Lewy body dementia (LBD) genetic evidence. Gene-level expression profiles from 42 postmortem prefrontal cortex samples in GSE150696, including controls, AD, DLB, and PDD, were analyzed using age- and sex-adjusted empirical-Bayes models with false discovery rate (FDR) correction, followed by sensitivity analyses, post hoc exploratory candidate selection, and integration with an external LBD multi-omics gene-prioritization dataset. No gene reached FDR < 0.05 in the DLB-versus-AD comparison. In contrast, SLC19A2, VAMP1, and COX5B were lower in DLB than in PDD and were FDR-supported in the primary age- and sex-adjusted model, although their statistical significance was partly model-dependent. A post hoc cross-disease analysis identified 60 exploratory candidates, of which SYT11 was the only gene overlapping with the published LBD-prioritized gene set. The overall 60-gene set was not significantly enriched for LBD-associated genes. These findings did not demonstrate broad robust disease–disease differences and are consistent with substantial molecular overlap, while remaining compatible with limited statistical power. A limited number of transcriptomic candidates, including the exploratory SYT11 overlap, warrant independent validation.