Dr. M’s SPA Newsletter Volume 16 Issue 18 – Autism and Microbiomes

Autism and Diagnosis

Metabolites and Phenotypes

In a brand new paper entitled. “Elevated Microbially-Derived Metabolites in Autism: A Possible Diagnostic Screening Test for a Distinct ASD Phenotype,” Dr. Flynn and colleagues investigated whether specific urinary metabolites produced by intestinal microbes could serve as predictive biomarkers for autism spectrum disorder. The study proposes that a large subset of children with autism may represent a biologically distinct phenotype characterized by markedly elevated microbial metabolites, which the authors term ASD-MDM (Autism Spectrum Disorder associated with Microbially-Derived Metabolites).

The investigators analyzed urine samples from 52 children with ASD and 47 typically developing (TD) controls, ages 2–11 years. They measured microbial metabolites derived primarily from phenylalanine metabolism, tryptophan metabolism, and yeast metabolism. These were chosen because decades of autism, microbiome, and metabolic research have repeatedly implicated abnormalities in microbial metabolism of aromatic amino acids, especially phenylalanine and tryptophan, along with evidence of elevated fungal/yeast metabolites in subsets of children with ASD.

The findings were striking. Children with ASD demonstrated significantly higher concentrations of many microbial metabolites than controls. Some metabolites were elevated by hundreds to thousands of percent, and in certain children concentrations were reported to be 100–1000 times higher than the highest levels observed in any control participant. Twenty-three of twenty-four measured microbial metabolites were higher in ASD participants. Ninety percent of the ASD participants (45 of 50) had one or more extremely elevated MDMs. Particularly notable were elevations in compounds related to p-cresol, p-cresol sulfate, phenylacetylglutamine, indole derivatives, and arabinitol, suggesting abnormalities in microbial metabolism involving aromatic amino acids and yeast overgrowth.... Also, Inflammation and Allergy.

Enjoy, Dr. M