Gut microbiota signature in treatment-naïve attention-deficit/hyperactivity disorderOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study asked whether the gut microbiome composition differs in adults with attention-deficit/hyperactivity disorder. It is described as the largest microbiome study of ADHD to date. Researchers profiled fecal bacteria using 16S ribosomal RNA gene sequencing of the V3-V4 region. They compared diversity and relative abundance of taxa between patients and controls. Logistic regression models tested whether selected genera predicted ADHD status and whether they correlated with symptom severity, age, or body mass index.
Who was studied?
The sample included 100 medication-naive adults with ADHD diagnosed by DSM-5 criteria and 100 sex-matched healthy controls. All participants were recruited in Catalonia, Spain, and reported European ancestry. Patients had no comorbid psychiatric disorders and were free of antibiotics or probiotics before stool collection. Controls were screened to exclude ADHD symptoms. Stool was collected at home, stabilized, and stored frozen. This adult, medication-naive design contrasts with earlier pediatric ADHD studies.
What were the most important findings?
Overall diversity did not differ between groups, but specific taxa did. One phylum, seven families, and 17 genera showed differential abundance by at least one method. ADHD adults had lower Gracilibacteraceae and higher Selenomonadaceae and Veillonellaceae at the family level. Several genera were also higher or lower in the patient group. Four selected genera plus age, sex, and body mass index explained 15 percent of ADHD variance, with 74 percent sensitivity and 71 percent specificity. No genus correlated with symptom scores.
What are the greatest implications of this study?
The results support the idea that gut microbiome differences accompany ADHD in adults, not just children. Specific taxa may contribute to phenotypic variability in the disorder. Because diversity was unchanged, the signal lies in a few taxa rather than broad community shifts. The study cannot establish whether these microbes cause ADHD. The authors caution that the same dataset defined and tested the signature, risking overfitting, and independent longitudinal cohorts are needed to confirm the findings.