Researchers from the Azrieli Faculty of Medicine of Bar-Ilan University have made what they call a significant breakthrough in understanding autism spectrum disorder (ASD), a neurodevelopmental condition affecting millions worldwide. 

Their recently published study suggests a potential connection between ASD and the composition of the gut microbiome.

ASD is characterized by challenges in social communication and repetitive behaviors. While its exact causes remain elusive, scientists have long sought to uncover the underlying mechanisms. 

The Bar-Ilan University researchers conducted a thorough analysis of the gut microbiome in 96 individuals diagnosed with ASD and in 42 neurotypical individuals, leading to some striking findings.

What is the gut microbiome?

Before diving into those findings however, a brief explanation of gut microbiomes and how they work: gut microbiomes refer to the community of microorganisms, including bacteria, fungi, viruses and other microbes, that live in our digestive tract, particularly in the intestines. These tiny organisms play a crucial role in digestion, metabolism and immune function.

The researchers looked at both alpha and beta bacterial diversity, finding notable differences in both. 

Alpha diversity measures how many different types of bacteria were present within each individual’s gut. Beta diversity compares and contrasts the microbiomes of individuals with ASD and those of neurotypical individuals.

Alpha diversity was unexpectedly increased in those with ASD, indicating that they harbor a wider variety of microbes than their neurotypical peers.

Additionally, people with ASD had more of specific types of bacteria, particularly the phylum Bacteroidetes and the genus Bacteroides. While these Bacteroides are normally present in the human gut microbiome, they may have adverse effects on health when increased in abundance. 

Testing on mice revealed that excess Bacteroides administered at birth was linked to social behavior dysfunction, increased repetitive behaviors and gene-expression dysregulation.

Lead researcher Prof. Evan Elliott emphasized the implications of the findings. 

“Our research suggests that an overabundance of Bacteroides, particularly in early life, may have functional consequences for individuals with ASD,” he said. “This sheds new light on the complex interplay between the microbiome and neurodevelopment in individuals with ASD.”

This study offers opportunities to investigate how microbial interventions in early developmental stages could impact brain development over the long term.

Elliott’s research has garnered international interest, and was recently selected as one of 34 projects that received a combined $6.2 million in funding for innovative autism research and care from the Eagles Autism Foundation.