Gastrointestinal involvement of autism spectrum disorder: focus on gut microbiota

ABSTRACT

Introduction

Autism spectrum disorder (ASD) is a neurodevelopmental disorder typical of early age, characterized by impaired communication, social interaction, and repetitive behaviors. ASD patients frequently suffer from gastrointestinal (GI) symptoms. Neuro-psychological functions, intestinal homeostasis, and functional GI disturbances are modulated by the gut microbiota through the so-called ‘microbiota-gut-brain axis’.

Areas covered

Literature regarding GI symptoms among the ASD community as well as the involvement and modulation of the gut microbiota in GI disturbances of ASD patients was searched. Constipation, diarrhea, reflux, abdominal bloating, pain, and discomfort are reported with variable prevalence. ASD is characterized by a reduction of Bacteroidetes/Firmicutes, of the abundance of Bacteroidetes and other imbalances. ASD patients with GI symptoms present microbial changes with plausible relation with deficiency of digestive enzymes, carbohydrate malabsorption, selective eating, bacterial toxins, serotonin metabolism, and inflammation. The strategies to mitigate the GI distress through the gut microbiota modulation comprise antimicrobials, probiotics, prebiotics, fecal microbiota transplantation, and dietary intervention.

Expert opinion

The modulation of the gut microbiota in ASD individuals with GI disturbances seems a promising target for the future medicine. A standardization of the research strategies for large-scale studies together with a focus on poorly explored fields is necessary to strengthen this hypothesis.

KEYWORDS:

• Autism spectrum disorder
• gastrointestinal Symptoms
• gut Microbiota
• gut-Brain Axis
• probiotics
• prebiotics
• fecal Microbiota Transplantation
• diet

Article highlights

• Autism spectrum disorder is a multifactorial neurodevelopmental condition in which the gut microbiota plays a key role.

• Gastrointestinal disorders are frequent in patients with autism spectrum disorder with variable prevalence (20-70%).

• Dysbiosis is common among the patients with autism spectrum disorder and specific changes of the gut microbiota are described among the patients with gastrointestinal disturbances.

• A modulation of the gut microbiota through antimicrobials, probiotics, prebiotics, fecal microbiota transplantation, and diet seems a promising strategy to ameliorate the gastrointestinal manifestations, but further studies are necessary.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

One reviewer would like to disclose they have patents pending on FMT for autism, and have received funding and consulting fees from companies researching FMT for autism. All other peer reviewers on this manuscript have no relevant financial or other relationships to disclose

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This paper was not funded.