Chinese scientists have found types of bugs in children’s guts that are linked to autism spectrum disorder.
The team looked at the gut bugs of 1,627 children aged between one and 13 and identified 14 archaea – which are like bacteria – 51 bacteria, 7 fungi, 18 viruses, 27 microbial genes and 12 metabolic pathways that were altered in kids with ASD.
They then used artificial intelligence (AI) to see if the presence of 31 different microbiota could predict whether a child had ASD and found this had a higher diagnostic accuracy than just looking at one type of bug, such as bacteria, alone – suggesting an ASD test could potentially be developed by looking at the composition of children’s microbiomes.
The study, published in Nature Microbiology, highlighted that in the past decade, the gut microbiome has been shown to play a significant role in modulating the gut–brain axis by regulating neuroimmune networks and directly communicating with the brain.
Lead author, Dr Siew Ng from Hong Kong’s Microbiota I-Center (MagIC), explained that preclinical studies have shown that children with ASD had an altered gut microbiota composition and delayed development of the gut microbiota.
“Furthermore, the transfer of faecal microbiota from individuals with ASD into germ-free mice promoted autistic-like behaviour, whereas faecal microbiota transplantation from healthy individuals to children with ASD resulted in improvements in symptoms,” he said.
“In this study, we explored multi-kingdom analyses of gut archaea, bacteria, fungi, viruses and their genes and functions, presented metagenomic analyses of 1,627 children considered neurotypical or with ASD, with extensive phenotype data, and validated our findings in public datasets of 237 faecal metagenomes.”
“Using machine learning, Ng and colleagues created a model based on a panel of 31 microbes and functions, which had higher diagnostic accuracy in identifying both males and females with ASD compared with panels of gut microbiome markers from a single kingdom (such as bacteria or archaea).”
Overall, children with ASD showed a decrease in the diversity of archaea, bacteria and viruses compared with children considered neurotypical. A total of 14 archaeal, 51 bacterial, 7 fungal and 18 viral species showed differential abundances between children considered neurotypical and children with ASD.
“The relative abundance of 80 out of 90 identified microbial species was found to be significantly decreased in children with ASD compared with children considered neurotypical. This finding was most pronounced for the bacterial communities, where 50 bacterial species were depleted in children with ASD whereas only one bacteria species was enriched,” Dr Ng said.
“Alterations in bacterial species in children with ASD were driven by the depletion of Streptococcus thermophilus and short-chain fatty acids-producing bacteria, such as Bacteroides sp.PHL2737 and Lawsonibacter asaccharolyticus.
“In addition, we found that specific microbial functions may contribute to ASD pathogenesis via the deregulation of ubiquinol and thiamine diphosphate biosynthesis. Ubiquinol and thiamine-related metabolites play crucial roles in mental health and neural signal transduction.”
Their research has also helped to address the heated debate about whether ASD-associated gut dysbiosis was driven solely by dietary preferences.
“Our results showed that diet has an impact on the gut microbiome in children with ASD. However, ASD-associated microbiome alterations including microbial diversity and composition remained present after correction for dietary factors in our analysis,” Dr Ng said.
“We have also included an analysis of two common childhood diseases known to have an association with gut microbiome alterations, atopic dermatitis, and ADHD, and demonstrated that our 31-marker panel remained specific to ASD diagnosis.”