The process for diagnosing a child with autism relies heavily on a parent’s description of their child’s behavior and a professional’s observations. It leaves a lot of room for human error.
Parents’ concerns it can skew how they answer the questionnaires. Providers may have biases, leading them to underdiagnose certain groups. Children can experience widely varying symptoms, depending on factors such as culture and gender.
ONE study published Monday in Nature Microbiology adds to a growing body of research that suggests an unlikely path to more objective autism diagnoses: the gut microbiome.
After analyzing more than 1,600 stool samples from children ages 1 to 13, the researchers found several distinct biological “markers” in the autistic children’s samples. Unique traces of gut bacteria, fungi, viruses and more could someday form the basis of a diagnostic tool, said Qi Su, a researcher at the Chinese University of Hong Kong and lead author of the study.
A biomarker-based tool could help professionals diagnose autism earlier, giving children access to treatments that are more effective at an earlier age, he said.
“There were too many left in the questionnaires,” said Sarkis Mazmanian, a microbiome researcher at the California Institute of Technology. “If we can get to something we can measure — whatever that is — that’s a huge improvement.”
For decades, researchers have searched the human genome, medical history and brain scans for a reliable marker of ASD, with limited success. The Food and Drug Administration has approved two diagnostic tests based on eye-tracking software, which Dr. Sue said require significant input from a psychiatrist.
Over the past 15 years, some researchers have begun to investigate whether feces, which are a window into the trillions of fungi, bacteria and viruses that live in the gut, might offer a clearer answer. Until now, most of these studies were based on small groups and often produced mixed results.
This idea that the gut microbiome may play a role in the development of autism is still controversial among researchers, said Gaspar Taroncher-Oldenburg, a microbiologist who has published paper landmark for the matter last year.
He called Monday’s paper, one of the largest studies of its kind, a “significant milestone” in the wider acceptance of this line of research. “There is a change in the winds,” he said. “People are now accepting that the microbiome is not just part of it, but can be a fundamental piece of the puzzle.”
In the new study, the researchers used machine learning to identify important biological differences between the stools of autistic children and the other samples.
Unlike previous studies, which focused primarily on gut bacteria, the researchers broadened their scope to look at other microorganisms in the gut, including fungi, archaea, and viruses, as well as related metabolic processes. The scientists identified 31 biological signatures that distinguished the groups.
Then, in an entirely new set of samples, they tested whether these markers could be used to correctly identify which stool samples belonged to someone with autism. Dr Su said the model made the correct predictions almost all the time.
But Dr. Su and Dr. Taroncher-Oldenburg cautioned that it was hard to say whether stool sample tests would work as well in a clinical setting.
More research is needed to be convinced skeptical scientists that these biomarkers are valid indicators of autism. Dr. Mazmanian, who was not involved in the new work, said he wanted to see studies clarifying exactly how the microbiome relates to autism and whether it plays a role in causing ASD
Some researchers argue The direction of this relationship goes in the opposite direction: Autistic children are more likely to be “special eaters,” changing the composition of their microbiome.
Dr. Su said the study’s model also needs to be validated in a more diverse sample of children. Most of the samples came from children in Hong Kong.
“The current study is just the beginning of a long journey,” he said.
