Habitual Diet, Gut Microbiome Dysbiosis, and α-Synucleinopathy Conversion in Isolated Rapid Eye Movement (REM) Sleep Behavior Disorder.

Summary

This observational cohort study of 287 iRBD patients and 208 controls investigated how habitual diet and gut microbiome dysbiosis relate to progression towards α-synucleinopathy over 4.2 years. iRBD patients showed lower adherence to healthful plant-based diets and higher consumption of refined grains and sweets; diet-microbiome interaction analysis revealed that 84.3% of iRBD-related gut species were associated with dietary factors. Higher coffee consumption and healthful plant-based diet patterns were protective against neurodegenerative conversion, whilst unhealthful plant-based foods and dysbiosis (particularly Ruthenibacterium lactatiformans) predicted worse outcomes, suggesting diet-mediated microbial mechanisms in prodromal α-synucleinopathy.

Regional applicability

The study was conducted in Hong Kong and may not fully represent UK dietary patterns or microbiota composition, which differ in food availability, consumption habits and baseline microbial populations. However, the mechanistic findings regarding diet-microbiome-neurodegeneration associations could be relevant to UK populations with iRBD, though UK-specific validation would strengthen applicability to clinical practice.

Key measures

Plant-based diet indices (derived from food frequency questionnaires); shotgun metagenomic sequencing of gut microbiota; Cox proportional hazards models for neurodegenerative progression; mediation analyses of diet-microbe associations; adjusted odds ratios and hazard ratios for dietary and microbial predictors

Outcomes reported

The study examined associations between habitual dietary patterns and gut microbiome composition with longitudinal progression to α-synucleinopathy in patients with isolated REM sleep behaviour disorder, with 45 (15.7%) of 287 patients converting to neurodegenerative disease over a median 4.2-year follow-up.

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