The screening tool identifies specific molecules produced by gut bacteria to distinguish children with autism from typically developing peers.
Researchers at Arizona State University have developed a screening tool that tests urine for 17 microbial metabolites to identify children at risk for autism. The study, published in Molecular Psychiatry, suggests the test could allow for earlier diagnosis and treatment in children ages 2 to 11 years.
By measuring small molecules produced by microorganisms in the gut, the research team discovered they could distinguish children with autism spectrum disorder (ASD) from typically developing children with high accuracy. The “Microbially-Derived Metabolite (MDM) System” assigns a score based on how many metabolites in a child’s urine exceed a typical reference range. In clinical trials involving 99 children, the test demonstrated 90% sensitivity and 100% specificity.
“What we’ve discovered is that 80 to 90% of children with autism have extremely high levels of one or more microbially derived metabolites,” says Christina Flynn, PhD, first author of the study and research director for the Autism Diagnostics Laboratory, in a release. “Using this test will tell you which young children are at high risk for being diagnosed with autism, and guide treatment in those who have already been diagnosed to help them lead their best lives.”
The metabolites measured in the system include those derived from amino acids such as tyrosine, tryptophan, and phenylalanine, which are involved in neurotransmitter pathways. On average, children with ASD had approximately three elevated metabolites, while typically developing children in the study had none. Some metabolite levels in the ASD group measured 100 to 1,000 times higher than those in the control group.
“What’s really striking about the bacteria is that they make metabolites that are basically altered versions of serotonin and dopamine,” says James Adams, PhD, corresponding author and professor at Arizona State University, in a release. “These are two key neurotransmitters that affect mood, cognition and memory. This could explain many of the symptoms and co-occurring symptoms in children with autism — their social communication, anxiety, depression and attention.”
Based on these findings, the researchers propose a new phenotype called “ASD associated with microbially-derived metabolites,” or ASD-MDM. This subtype encompasses an estimated 90% of ASD cases. While the urine test is not intended as a stand-alone diagnosis, researchers say it can serve as a triage tool to prioritize children for full clinical evaluations.
The test is moving toward broader availability through Analutos, a partner laboratory in the United Kingdom. Flynn, who completed her PhD in chemical engineering at Arizona State University, also serves as a senior research scientist for Gut Brain Axis Therapeutics.
The research team notes that while the metabolites are strongly associated with symptoms, the study does not prove they cause autism. Further studies are planned to validate the findings across larger and more diverse populations and to understand how these molecules relate to the development of the condition.
“I am excited about the MDM test, which includes important microbial metabolites, previously hypothesized to be linked with autism,” says Rosa Krajmalnik-Brown, PhD, co-author and professor at Arizona State University, in a release. “This test can be a great way to assess this important microbial contribution.”
Photo caption: ASU Biodesign Institute researchers and co-authors of the study include (from left) professors Rosa Krajmalnik-Brown, Jim Adams, and Christina Flynn.
Photo credit: Andy DeLisle/ASU Knowledge Enterprise
