The Effects of Probiotics and Prebiotics on Gastrointestinal and BehaviouralSymptoms in Autism Spectrum Disorder

Background: Autism Spectrum Disorders (ASDs) are a group of prevalent neuropsychiatricdisorders. They present a complex and unknown etiology, which in most cases includes significantperipheral alterations outside the brain such as in the composition of gut microbiota. Becausethe gut microbiota is involved in modulating the gut-brain axis, several studies have suggested thatthe microbiome in the gut can modify metabolites which are able to cross the blood-brain barrierand modulate brain function. Methods: We reviewed the current evidence regarding microbiota alterations in patients with ASDand the effects of the administration of probiotics and prebiotics in these patients, both in terms ofgastrointestinal and behavioural symptoms. Results: Administration of a probiotic formulation containing different strains of Lactobacillus (L.acidophilus, L. rhamnosus, and others) and Bifidobacteria had beneficial effects upon these aforementionedsymptoms and their use is recommended in a subgroup of ASD patients that present gastrointestinaldisturbances. Nonetheless, the types of gastrointestinal disturbances that most benefitfrom such interventions remain to be elucidated in order to personalize the medical approaches. Conclusion: Recent clinical studies have shown that probiotic treatments can regulate the gut microbiotaand may result in improvements in some behavioral abnormalities associated with ASD.Trials using prebiotic fibers or synbiotics preparations are still lacking and necessary in order todeep in such therapeutic strategies in ASD with comorbid gastrointestinal disrturbances.