Relationship between Gut microbiome and brain volumes among Japanese MenOriginal 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 examined whether the gut microbiome is related to brain structure in apparently healthy adults. The researchers used 16S ribosomal RNA gene sequencing of stool samples to characterize gut microbiome composition and diversity. They paired this with brain magnetic resonance imaging and automated voxel-based morphometry to measure brain volumes, including gray matter and white matter. Statistical methods included principal coordinate analysis, linear discriminant analysis, and multivariable linear regression to test associations between microbiome measures and brain volume.
Who was studied?
The study population was 623 Japanese men drawn from the Shiga Epidemiological Study on Subclinical Atherosclerosis (SESSA), a population-based cross-sectional cohort. Stool samples were collected during the study's follow-up stage, and participants had a mean age of 68.0 years (SD 8.0), ranging from 46 to 83 years. All participants underwent brain MRI as part of the same assessment.
What were the most important findings?
After adjusting for age and total intracranial volume, gray matter volume showed a positive association with alpha diversity, specifically the Shannon index richness, at a q-value below 0.01. However, this association was no longer significant once the analysis further adjusted for body mass index, physical activity, smoking, drinking, and hypertension. Beta diversity, measured using weighted UniFrac distances via principal coordinate analysis, showed differences related to white matter volume, though the abstract text describing this result is incomplete. This pattern of the abstract is not about Christensenellaceae, Christensenella, leanness, BMI-associated taxa, or heritability; the study centers instead on gut microbiome diversity and brain morphometry.
What are the greatest implications of this study?
The findings suggest that in generally healthy older men, any apparent link between gut microbial diversity and gray matter volume may largely reflect shared lifestyle and metabolic factors such as body mass index, physical activity, smoking, drinking, and hypertension rather than a direct, independent relationship. This underscores the importance of adjusting for lifestyle and cardiometabolic confounders when studying gut-brain associations in human populations. The results also support continued investigation of beta diversity and white matter relationships as a potentially distinct avenue linking the gut microbiome to brain structure. Overall, the study adds population-based human evidence to a field previously dominated by animal models and specific patient populations.