Age and severity-dependent gut microbiota alterations in Tunisian children with autism spectrum disorder.

Alterations in gut microbiota and short chain fatty acids (SCFA) have been reported in autism spectrum disorder (ASD). We analysed the gut microbiota and fecal SCFA in Tunisian autistic children from 4 to 10 years, and results were compared to those obtained from a group of siblings (SIB) and children from the general population (GP). ASD patients presented different gut microbiota profiles compared to SIB and GP, with differences in the levels of Bifidobacterium and Collinsella occurring in younger children (4-7 years) and that tend to be attenuated at older ages (8-10 years). The lower abundance of Bifidobacterium is the key feature of the microbiota composition associated with severe autism. ASD patients presented significantly higher levels of propionic and valeric acids than GP at 4-7 years, but these differences disappeared at 8-10 years. To the best of our knowledge, this is the first study on the gut microbiota profile of Tunisian autistic children using a metataxonomic approach. This exploratory study reveals more pronounced gut microbiota alterations at early than at advanced ages in ASD. Although we did not account for multiple testing, our findings suggest that early interventions might mitigate gut disorders and cognitive and neurodevelopment impairment associated to ASD.

An Overview on Fecal Profiles of Amino Acids and Related Amino-Derived Compounds in Children with Autism Spectrum Disorder in Tunisia.

Autism spectrum disorder (ASD) is a neurodevelopmental pathology characterized by the impairment of social interaction, difficulties in communication, and repetitive behaviors. Alterations in the metabolism of amino acids have been reported. We performed a chromatographic analysis of fecal amino acids, ammonium, biogenic amines, and gamma aminobutyric acid (GABA) in Tunisian autistic children from 4 to 10 years, and results were compared with their siblings (SIB) and children from the general population (GP). ASD presented significantly higher levels of fecal amino acids than SIB and GP; differences being more pronounced in younger (4-7 years) than in older (8-10 years) individuals whereas no changes were found for the remaining compounds. Lower levels of histidine were the only difference related with severe symptoms of autism (CARS scale). A linear discriminant analysis (LDA) based on fecal amino acid profiles clearly separated ASD, SIB, and GP at 4 to 7 years but not at more advanced age (8-10 years), evidencing more pronounced alterations in younger children. The relationship of fecal amino acids with autism needs deeper research integrating blood analytical parameters, brain metabolism, and intestinal microbiota. Fecal amino acids could be targeted for designing personalized diets to prevent or minimize cognitive impairments associated with ASD.