Children suffering from autism have different concentrations of bacteria-produced chemicals - metabolites - in their feces as compared to those without Autism Spectrum Disorder, according to an Arizona State University study.
"Most gut bacteria are beneficial, aiding food digestion, producing vitamins and protecting against harmful bacteria. If left unchecked, however, harmful bacteria can excrete dangerous metabolites or disturb a balance in metabolites that can affect the gut and the rest of the body including the brain," said Dae-Wook Kang of the Biodesign Institute of Arizona State University, an author on the study, in a press release.
According to the U.S. Centers for Disease Control and Prevention, ASD associated with social, communication and behavioral challenges affect at least 1 in every 68 children, mainly boys. Most of them are diagnosed with autism as an adult.
Autistic children find it difficult communicating their needs to others, express their feelings, meeting people, making friends and fail to comprehend others and their thoughts. They like following a routine life and resist changes, according to National Autistic Society.
For the study, the researchers compared the fecal samples of children with (23) and without (21) ASD, NBC News reports. They found that children with ASD had at least seven of the 50 gut germs different than the second group. Some of them serve the role as message-carrying chemicals called neuro-transmitters.
"Most of the seven metabolites could play a role in the brain, working as neuro-transmitters or controlling neurotransmitter biosynthesis," said Kang. "We suspect that gut microbes may alter levels of neuro-transmitter-related metabolites affecting gut-to-brain communication and/or altering brain function."
In the study, children with ASD had reduced amounts of the metabolites homovanillate and N,N-dimethylglycine. The percentage of glutamine/glutamate was higher in this group. A disparity between glutamate and gamma-aminobutyric acid (GABA) transmission has been linked to the development of ASD-like behaviors like hyper-excitation.
Overall, children with ASD sheltered less diverse gut bacterial composition.
"Correlations between gut bacteria and neurotransmitter-related metabolites are stepping stones for a better understanding of the crosstalk between gut bacteria and autism, which may provide potential targets for diagnosis or treatment of neurological symptoms in children with ASD," said Kang.
A 2013 Arizona State University study found that children with autism had lower levels of three gut bacteria - Prevotella, Coprococcus and Veillonellaceae - than those without autism. On the other hand, a 2010 Imperial College London study found that children with autism have a different chemical fingerprint in their urine than non-autistic children.
