Longitudinal assessment of oral and gut microbiome overlap in patients with Alcohol Use Disorder undergoing inpatient treatment

Alcohol Use Disorder (AUD) is a condition associated with compulsive alcohol consumption and disruption across multiple physiological systems. This brief report builds on previously published research separately examining longitudinal changes in the oral and gut microbiomes of treatment-seeking individuals with AUD. Twenty-two participants diagnosed with severe AUD were enrolled in an inpatient treatment protocol (NCT02231840) and provided oral and stool samples over 28 days (goal 10 samples/participant). The aim of this brief report was to explore within-person overlap and compositional similarity of the oral and gut microbiomes at the genus level, using the Sorenson-Dice Index and Robust Aitchison Distance. Results indicated that the oral and gut microbiomes became less similar during the first week of treatment, with both the number of shared genera and Sorenson-Dice Index values decreasing significantly (<i>p</i> <.001). However, the Robust Aitchison Distance also decreased over time (<i>p</i> <.05), suggesting increased compositional similarity among the shared genera. These findings suggest early divergence of oral and gut microbiota during AUD treatment, where individuals were abstinent of alcohol, followed by stabilization of overlapping communities. This study highlights dynamic shifts in microbiome structure during a period of abstinence and underscores the importance of evaluating site-specific and cross-site microbial changes in AUD populations.