Brain-Body Crosstalk: Characterizing the Gut Microbiome in Autism Spectrum Disorder and Attention-Deficit/Hyperactivity Disorder

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Jurj, Miruna Iulia
Autism spectrum disorder , ADHD , Gut microbiome , Gut-brain axis , 16S , Behaviour , Diet
Background: Autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) are two of the most common neurodevelopmental conditions in children. Previous studies have suggested diet-induced alterations to gut microbial composition may be associated with subsequent behavioural/mood outcomes, however current approaches do not consider the high intra-individual variation in gut microbial composition over time. This study aims to describe a longitudinal role of the gut-brain axis in children with ASD/ADHD where diet-induced alterations of gut microbial composition may be involved in behaviour/mood presentation in individuals over time. The primary objectives of this study are to: (1) characterize the gut microbiome of ASD/ADHD children, (2) assess whether changes to gut microbial composition are associated with dietary and behavioural alterations, and (3) assess temporal variation within individuals. Methods: Participants consisted of children ages 6-17 with a physician-confirmed diagnosis of ASD and/or ADHD. A daily stool sample and a daily diet/behaviour questionnaire were completed over a 14-day study period. Microbial composition of the stool samples was determined using 16S rRNA next-generation sequencing (NGS). Results: Comparisons of gut microbial characteristics by participant demographics (age, sex, SES, ethnicity) revealed significant differences in beta diversity (p < 0.05). Between-individual comparisons found significant differences in alpha (p = 0.0336) and beta diversity (p = 0.001) between ASD, ADHD and comorbid ASD/ADHD diagnoses however no significant differences across behavioural symptom severity and GI issues (p > 0.05). Within-individual comparisons suggest differential intra-individual susceptibility to gut microbial alterations relating to behaviour and diet. Conclusions: This study highlights the importance of assessing within-individual variation in gut microbial alterations and host responsiveness and demonstrates the significant temporal variability of the gut microbiome. These results may also suggest that changes to the microbiome (diet-induced or otherwise) may have the capacity to reduce undesired symptoms or behaviours in some individuals.
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