Analysis of a stool sample could one day help diagnose autism much earlier and much faster, enabling earlier treatment for patients.

This, at least, is the hope of research carried out at the Chinese University of Hong Kong, the results of which were recently published in the medical journal Nature Biology.

The study’s authors examined stool samples from 1,627 children aged between 1 and 13, including some with autism. They painted a complete picture of these samples by analyzing the bacteria they contained, but also viruses, fungi and single-celled microorganisms called archaea.

They found that 51 types of bacteria, 18 viruses, 14 archaea and seven fungi were different in autistic children. The artificial intelligence was then able to identify autistic children with 82 per cent accuracy.

“The stool test they did is absolutely not simple,” says Dr. Mickael Bouin, a gastroenterologist at the Centre hospitalier de l’Université de Montréal (CHUM). It’s very complex, and there aren’t many teams in the world capable of doing it right now.’

At the very least, he added, this study opens up a new avenue ‘to try and better understand the disease’. It may also one day enable children to be screened earlier, so that some can be prioritized, he added.

“Autism remains a developmental disorder,” said Dr Bouin. The diagnosis will always have to be validated by an expert in autism, not by an expert in gut microbiota.”

Previous studies had already revealed that autistic people have a different intestinal microbiota, he pointed out. Experiments carried out on mice had generated similar results, in addition to showing that the symptoms of autistic mice could be reduced by modifying their microbiota, and that healthy mice could be given autistic symptoms by feeding them the gut microbiota of an autistic mouse.

It’s a chicken-and-egg question,” said Dr Bouin. But we feel that (the intestinal microbiota) has an effect on the brain, and we know that for several diseases.”

Indeed, the authors of the study admit that it is not yet possible to say whether autism is responsible for this different microbiota, or whether the different microbiota is responsible for autism.

But in light of their findings, the authors believe that microbiota may influence the severity or expression of autism spectrum disorder symptoms. This raises the possibility that patients could one day be offered personalized interventions to endow them with a more varied gut microbiota.