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Effects of Probiotic Supplementation on Gastrointestinal, Sensory and Core Symptoms in Autism Spectrum Disorders: A Randomized Controlled Trial

Santocchi E, Guiducci L, Prosperi M, Calderoni S, Gaggini M, Apicella F, Tancredi R, Billeci L, Mastromarino P, Grossi E, Gastaldelli A, Morales M, Filippo Muratori F (2020) Frontiers in Psychiatry Sep 25;11:550593 doi: 10.3389/fpsyt.2020.550593 

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The microbiota-gut-brain axis has been recently recognized as a key modulator of neuropsychiatric health. In this framework, probiotics (recently named "psychobiotics") may modulate brain activity and function, possibly improving the behavioral profiles of children with Autism Spectrum Disorder (ASD).

We evaluated the effects of probiotics on autism in a double-blind randomized, placebo-controlled trial of 85 preschoolers with ASD (mean age, 4.2 years; 84% boys). Participants were randomly assigned to probiotics (De Simone Formulation) (n=42) or placebo (n=43) for six months.

Sixty-three (74%) children completed the trial. No differences between groups were detected on the primary outcome measure, the Total Autism Diagnostic Observation Schedule - Calibrated Severity Score (ADOS-CSS).

An exploratory secondary analysis on subgroups of children with or without Gastrointestinal Symptoms (GI group, n= 30; NGI group, n=55) revealed in the NGI group treated with probiotics a significant decline in ADOS scores as compared to that in the placebo group, with a mean reduction of 0.81 in Total ADOS CSS and of 1.14 in Social-Affect ADOS CSS over six months.

In the GI group treated with probiotics we found greater improvements in some GI symptoms, adaptive functioning, and sensory profiles than in the GI group treated with placebo.

These results suggest potentially positive effects of probiotics on core autism symptoms in a subset of ASD children independent of the specific intermediation of the probiotic effect on GI symptoms.

Further studies are warranted to replicate and extend these promising findings on a wider population with subsets of ASD patients which share targets of intervention on the microbiota-gut-brain axis.


This randomised controlled trial - the gold standard study design for investigating causal effects - found preliminary evidence that probiotic supplementation vs placebo may be of benefit in some children with ASD.  

Findings differed between children with and without major gastrointestinal (GI) symptoms, as core (behavioural) ASD symptoms were significantly reduced only in the latter group, while probiotics reduced both sensory and GI symptoms in the latter.

As the researchers emphasised, more research is needed, but these findings add to the increasing evidence that gut microbial imbalances can affect brain function and behaviour, as well as gut and immune health (all of which are fundamentally inter-related).  

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