Autism Spectrum Disorders and the Gut Microbiota

Abstract

In recent years, there has been an emerging interest in the possible role of the gut microbiota as a co-factor in the development of autism spectrum disorders (ASDs), as many studies have highlighted the bidirectional communication between the gut and brain (the so-called “gut-brain axis”). Accumulating evidence has shown a link between alterations in the composition of the gut microbiota and both gastrointestinal and neurobehavioural symptoms in children with ASD. The aim of this narrative review was to analyse the current knowledge about dysbiosis and gastrointestinal (GI) disorders in ASD and assess the current evidence for the role of probiotics and other non-pharmacological approaches in the treatment of children with ASD. Analysis of the literature showed that gut dysbiosis in ASD has been widely demonstrated; however, there is no single distinctive profile of the composition of the microbiota in people with ASD. Gut dysbiosis could contribute to the low-grade systemic inflammatory state reported in patients with GI comorbidities. The administration of probiotics (mostly a mixture of Bifidobacteria, Streptococci and Lactobacilli) is the most promising treatment for neurobehavioural symptoms and bowel dysfunction, but clinical trials are still limited and heterogeneous. Well-designed, randomized, placebo-controlled clinical trials are required to validate the effectiveness of probiotics in the treatment of ASD and to identify the appropriate strains, dose, and timing of treatment.

Fecal Microbiota Transplantation in Neurological Disorders

“…The exact etiology is unknown: a combination of genetic and environmental risk factors, dysregulation of the immune system, inflammation and also maternal factors is proposed (Fattorusso et al, 2019). Increased systemic (Ashwood et al, 2011) and neuroinflammation (Vargas et al, 2005;Li et al, 2009) and even brain-specific autoantibodies (Vojdani et al, 2002;Silva et al, 2004;Connolly et al, 2006;Cabanlit et al, 2007;Wills et al, 2009), though not confirmed in another study (Todd et al, 1988), have been observed in ASD patients.…”

“…Increased systemic (Ashwood et al, 2011) and neuroinflammation (Vargas et al, 2005;Li et al, 2009) and even brain-specific autoantibodies (Vojdani et al, 2002;Silva et al, 2004;Connolly et al, 2006;Cabanlit et al, 2007;Wills et al, 2009), though not confirmed in another study (Todd et al, 1988), have been observed in ASD patients. Hyperserotoninemia in ASD patients may also contribute to the etiology (Fattorusso et al, 2019).…”

A quasi-paired cohort strategy reveals the impaired detoxifying function of microbes in the gut of autistic children

“…and Candida albicans ( 8, 9 ). The dysbiosis of the ASD microbiome is believed to be associated with inflammation in intestinal epithelia and increased permeability of the gut-blood barrier ( 10 ). However, the mechanisms of how the intestinal microbiome affects ASD pathogenesis are not fully understood.…”

Inflammation (IL-1β) Modifies the Effect of Vitamin D and Omega-3 Long Chain Polyunsaturated Fatty Acids on Core Symptoms of Autism Spectrum Disorder—An Exploratory Pilot Study

“…Undesired pro-inflammatory gastrointestinal side effects of anti-inflammatory treatments [70] have been discussed as a limitation of such therapies, which may also result in heterogeneity in treatment response. In light of the high prevalence of gastrointestinal disorders in children with ASD [71], finding therapies with little or no gastrointestinal adverse effects is of high importance. Vitamin D and omega-3 LCPUFA have been shown to positively affect gut microbial communities, mucosal homeostasis, and gut inflammation as well as systemic inflammation [29,31,72,73].…”