Altered gut bacteria raising the rate of ASD?

May 29, 2014

Compared with children without autism spectrum disorder (ASD), children with ASD have significantly altered levels of certain bacteria-produced gut metabolites that affect brain function, according to a small study presented as a poster presentation at this year’s American Society for Microbiology meeting in Boston, Massachusetts.

 

Compared with children without autism spectrum disorder (ASD), children with ASD have significantly altered levels of certain bacteria-produced gut metabolites that affect brain function, according to a small study presented as a poster presentation at this year’s American Society for Microbiology (ASM) meeting in Boston, Massachusetts.

The results provide further evidence that bacteria in the gut may be associated with autism, says the ASM.

Although most bacteria in the gut are helpful, some, particularly if left unchecked, excrete chemicals or metabolites that upset the body’s balance, including that of the brain.

Researchers from Arizona State University looked at a number of bacteria and metabolites in children’s guts by examining fecal samples. In their study, they included 21 children without ASD and 23 children with ASD. They found that those children with ASD have significantly different concentrations of 7 of 50 compounds identified. Most of the 7 play key roles in the brain, working as neurotransmitters or contributing to neurotransmitter biosynthesis.

Generally, they found that children with ASD have distinct and less varied gut bacteria. Specifically, they have higher levels of caprate and glutamine and a higher glutamine/glutamate ratio. Glutamine and glutamate are metabolized by gamma-aminobutyric acid (GABA). Experts have linked an imbalance between glutamate and GABA to ASD behaviors like hyperexcitation.

The investigators also found that the children with ASD have lower levels of homovanillate (produced when dopamine is broken down) and N,N-dimethylglycine (used to build proteins and neurotransmitters). Experts have used the latter to reduce ASD symptoms and seizures.

The researchers are investigating whether they could transplant fecal material from typical children into the guts of children with ASD to reverse the changes in their microbiome. 


 

 

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