IN Parkinson’s disease (PD), gut microbiome imbalances and early symptoms like REM sleep behavior disorder (RBD) are increasingly recognized as clues to the condition’s origins and progression. A new study investigates how gut microbiota dynamics differ based on whether PD is preceded by premotor RBD, a feature of what is often referred to as “body-first” PD.
The study examined stool samples from 104 individuals with PD, of whom 57 had a history of RBD (PD-RBD(+)), and 85 healthy spouses used as controls. Researchers found that the gut microbiome in PD-RBD(+) individuals remained relatively stable across disease stages. In contrast, the microbiome in those without RBD before diagnosis (PD-RBD(-)) changed more dynamically as the disease progressed.
Early-stage PD-RBD(+) patients had increased levels of Escherichia and Akkermansia, bacteria associated with biofilm formation and mucin degradation, respectively. Functional gene analysis supported these findings, revealing enrichment of pathways tied to host mucosal interaction. Notably, genes involved in UDP-GlcNAc synthesis and recycling, negatively associated with pathogenic biofilm formation, were decreased in this group. This finding was validated in an independent cohort.
Additionally, fiber-associated gut bacteria were reduced in early PD-RBD(+), and their microbiota showed a greater capacity for degrading mucin over dietary fiber, as indicated by carbohydrate-active enzyme (CAZyme) profiles. This imbalance could exacerbate inflammation or compromise gut integrity, potentially worsening PD pathophysiology.
These findings highlight a potentially distinct biological trajectory in patients with PD-RBD(+), reinforcing the concept of body-first versus brain-first PD. The authors suggest that future therapeutic strategies may need to consider RBD history when targeting the gut microbiome in PD management.
Reference:
Shin J et al. Distinct gut microbiome characteristics and dynamics in patients with Parkinson’s disease based on the presence of premotor rapid-eye movement sleep behavior disorders. Microbiome. 2025;13(1):108.
