Comparative Meta-Analysis of the Gut Microbiome Between ADHD and Healthy Human Cohorts

Attention deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental condition characterized by inattention, impulsivity, and hyperactivity, and is believed to involve altered dopamine signaling. Growing evidence suggests that the gut microbiome may contribute to neurobehavioral conditions, including ADHD. In this study, we examined differences in gut microbiome composition, measured using metagenomics, between healthy and ADHD-affected individuals, and evaluated age- and gender-related variation within the ADHD population. We analyzed publicly available gut microbiome datasets from the American Gut Project, NCBI, and MGnify, and retrieved data from 496 ADHD and 419 healthy individuals. Further, metadata and taxonomic abundance were processed using RStudio, normalized to sequencing depth, and analyzed at the genus level. Both groups shared several gut bacteria, including Blautia, Bacteroides, Faecalibacterium, Roseburia, and Alistipes, indicating a broadly similar core microbiome. However, individuals with ADHD showed differences in the stability and persistence of certain core taxa, such as Proteobacteria and the unclassified genus Prevotellaceae, which were uniquely present in the ADHD group. Further, PERMANOVA showed that age and gender explained a small yet significant difference in microbial variation (Rsquare = 0.0437, p = 0.001), with greater variability observed between males and females than across age groups. Dispersion analysis revealed significant microbial variability between males and females (p = 0.001), whereas age groups showed no significant variation (p = 0.792). Overall, these results suggest that differences in the gut microbiome between individuals with ADHD and healthy individuals are subtle. Clinically, this highlights the need to consider broader biological, environmental, and lifestyle influences- such as diet, medication use, and comorbidities- when evaluating the potential role of the gut microbiomes in ADHD.