Microbiome and ASD

According to this 2020 paper, research studies are looking into the composition of gut microbiota as a possible factor in the pathogenesis of autism spectrum disorders (ASD) since functional gastrointestinal disorders are fairly prevalent issues and are linked with ASD. The aim of this narrative review was to examine the microbial profile of individuals with and without ASD and find associations between microbial profiles with functional gastrointestinal disorder comorbidity, and ASD pathogenesis. The results demonstrated that prevalence and risk of functional gastrointestinal disorders are related to severity of ASD (incidence was significantly higher in children with autism). Also, there were differences in bacterial and fungal diversity between the guts of ASD and non-autistic children. It should be noted that there are limitations with these studies analyzing gut microbiota - for example a varied range of methodologies were employed. Furthermore, covariate analysis revealed that the results were influenced by numerous factors such as demographics, diet, disease severity, GI comorbidity and allergies. [NPID: gut microbiota, gut microbiome, gastrointestinal, gut disorders, functional gastrointestinal disorders, gut-brain axis, ASD, autism, autism spectrum disorder]

This is a narrative review written in 2019 that aimed to evaluate the available research on dysbiosis (imbalance in gut microbial community) and gastrointestinal (GI) disorders in autism spectrum disorder (ASD), while also examining the evidence for the role of probiotics and other non-pharmacological approaches in the treatment of children with ASD. After analyzing the research papers, Fattorusso et al. found that gut dysbiosis was well documented in autistic children. However, there was no unique profile of gut microbiota composition specific to people with ASD. An imbalance in gut microbial community can contribute to the low-grade systemic inflammatory state reported in patients with GI comorbidities. The most promising treatment for the neurobehavioral symptoms and bowel dysfunction is probiotics but the current clinical trials are not consistent and are few in number. 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, doses, and timing of treatment. [NPID: probiotics, gut microbiota, gut microbes, gut bacteria, gut health, ASD, autism, autism spectrum disorder, autistic, children, gastrointestinal, GI, inflammation]

Although the cause of autism spectrum disorder (ASD) has not yet been confirmed, this 2018 article highlights that a disturbance of the gut-brain axis (communication that exists between the gut, microbiota, and brain) may be an important factor that contributes to autism. In this study, the fecal microbiota of 30 children with ASD were compared with that of 24 healthy children using next-generation gene sequencing. All participants were recruited from India. The autistic kids were also assessed on several markers associated with ASD such as the INCLEN Diagnostic Tool for Autism Spectrum Disorder (INDT-ASD) and the Indian Scale for Assessment of Autism (ISAA) tool. There was a notable imbalance in microbiota communities in the gut of autistic children, with higher abundances of families Lactobacillaceae, Bifidobacteraceae, and Veillonellaceae, compared to typically developing children. The dominant family in the gut microbiome of healthy children was Prevotellaceae. A comparative meta-analysis with another American dataset consisting of 20 ASD and 20 healthy control subjects (children) of similar age revealed a significantly high abundance of genus Lactobacillus in ASD children among both populations. In conclusion, microbial dysbiosis (imbalance in the microbial community) was evident in the gut microbiome of ASD children, which was associated with a high abundance of the Lactobacillus species. [NPID: gut microbiota, gut microbiome, gut bacteria, GI, gastrointestinal, autism, ASD, autism spectrum disorder, India, Indian, dysbiosis, autistic, children]

The objective of this 2019 pilot study was to characterize the oral and gut microbiome of patients with autism spectrum disorders (ASD), and to compare these features with those of typically developed individuals. In addition, Kong et al. looked at the use of microbiome markers for ASD diagnosis and subtyping of clinical comorbid conditions. Another aim was to develop microbiome biomarkers that would help subsequent clinical trials report their findings on probiotic supplementation. The authors found that previous studies had paid little attention to the oral bacteria of patients. The results indicated distinct features in the gut and salivary microbiota, with variations found between typically developed people and autistic patients. Moreover, this present study attempted to find out microbiome characteristics associated with clinical subtypes such as allergies, abdominal pain, and abnormal dietary habits. The researchers determined that the diagnosis of ASD is potentially highly subjective, with a high level of reliance on psychological testing. Hopefully, the preliminary evidence for developing microbial markers presented in this study can be used to diagnose or guide therapy of ASD and comorbid conditions. Furthermore, these preliminary results can help future research with experiments such as testing whether modifying the gut and oral microbiome can improve co-morbid conditions in patients with ASD, and positively affect ASD symptomatology. [NPID: ASD, autism, autism spectrum disorder, autistic, gut microbiome, oral health, mouth bacteria, mouth microbiome, gut microbiota, gut health, gastrointestinal, GI]

In this 2020 study, the microbiota present in the gut of individuals with and without attention deficit hyperactivity disorder (ADHD) was extracted and placed in young, male mice. The animals’ behaviors were then analyzed (via a behavioral test), as well as its brain structure and function through magnetic resonance imaging (MRI). The researchers who conducted this experiment hypothesized that mice given the microbiota of persons with ADHD would be different in brain function and/or structure to mice that receive microbiota of persons without ADHD. The fecal microbiota of mice colonized with ADHD microbiota were distinguishable to that of mice transplanted with control microbiota. Examining the brain there was a reduction in structural integrity of both white and grey matter regions in mice that received ADHD microbiota. White matter integrity was strongly linked with distinct microbiota expression. Furthermore, the MRI indicated decreased connectivity between the right motor and right visual cortices in the mice colonized with ADHD microbiota. These regions are said to be altered in several neurodevelopmental disorders. The open-field test also revealed heightened anxiety in the mice given ADHD microbiota. To summarize these results, a change in microbial composition of the gut may stimulate further alterations in brain structure and function, as well as modifications in animal behavior. [NPID: gut microbiota, gut microbiome, gut bacteria, ADHD, attention deficit hyperactivity disorder, gut health, animal study, neurodevelopmental disorders]

This 2019 paper explains that the bacteria community (microbiota) in the gut may have a role in the physiological processes associated with autism spectrum disorder (ASD), since gastrointestinal dysfunction is a comorbidity that often accompanies ASD. Manipulation of the gut microbiota has been reported to reduce the symptoms of ASD, but studies have yet to confirm the patterns in altered bacterial species specific to this disorder. This meta-analysis examined the bacterial genera abundances seen in the gut of healthy control subjects and of patients with ASD. Nine studies were included in this meta-analysis, with data on 254 individuals with ASD. Autistic children were found to possess lower percentages of Akkermansia, Bacteroides, Bifidobacterium, and Parabacteroides and a higher percentage of Faecalibacterium in their guts, when compared with healthy controls. In addition, kids living with autism showed lower abundances of Enterococcus, Escherichia coli, Bacteroides, and Bifidobacterium and higher abundance of Lactobacillus (relative to control). This meta-analysis suggests an association between ASD and an alteration in gut microbiota composition. Future studies are recommended to assess the relationship between bacterial changes and symptoms of ASD, as this research would enhance the evidence for the accurate and appropriate treatment of autism. [NPID: autism, autism spectrum disorder, ASD, gut microbiota, gut microbiome, gut bacteria, meta-analysis, probiotics, children]

According to this 2020 article, dysbiosis (imbalance in microorganisms in the gut) and gastrointestinal comorbidities are often associated with autism spectrum disorder (ASD). Therefore, the aim of this present review was to investigate the differences in composition of gut microbiota in children with and without ASD. Firstly, electronic databases were searched to find relevant studies for this meta-analysis. A total of 18 studies were included, equating to a dataset of 493 children with ASD and 404 non-autistic individuals. The main microbiota found in the gut of ASD children were of the phyla Bacteroidetes, Firmicutes, and Actinobacteria. These were more abundant in the autistic children than the healthy control subjects. In addition, the kids with autism showed a significantly higher abundance of the genera Bacteroides, Parabacteroides, Clostridium, Faecalibacterium, and Phascolarctobacterium and a lower percentage of Coprococcus and Bifidobacterium (compared with non-autistic participants). In conclusion, this meta-analysis provides evidence that there is an imbalance in the gut microbiota community of autstic children, which may affect their development and the severity of their ASD symptomatology. Additional research is encouraged to enhance our current knowledge on the effectiveness of pre- or probiotics in reducing autistic behaviors. [NPID: autism, autism spectrum disorder, ASD, autistic, children, meta-analysis, dysbiosis, gut microbiota, gut microbes, gut bacteria, GI, gastrointestinal]

The purpose of this 2020 study was to analyze the microbiota living in the gut of children with attention deficit hyperactivity disorder (ADHD), and to determine the role of the gut microbiota in the development of this disorder. Wan et al. recruited 17 young children (aged 6-12 years) with ADHD who were treated in the Chinese PLA General Hospital in 2019, and 16 healthy children without ADHD (aged 6-12 years). Fecal samples were taken from the participants to compare the differences in abundance of bacteria between the two groups. There was no significant difference in diversity of bacteria between the children with and without ADHD. But the scientists noticed markedly lower populations of Faecalibacterium and Veillonellaceae, and higher abundances of Odoribacter and Enterococcus in the ADHD group compared with the control group. Moreover, there appeared to be dissimilarities in the metabolic pathways of neurotransmitters (including serotonin and dopamine) between the two groups. This study concluded that distinct compositions of the gut microbiota may influence the brain-gut axis and neurotransmitter levels, which can in turn affect ADHD symptoms. [NPID: attention deficit hyperactivity disorder, ADHD, children, China, Chinese, bacteria, microbiota, microbiome, neurotransmitters]

While many pediatric studies have investigated the relationship between autism spectrum disorder and the microbiome-gut-brain axis (the communication between the gut microbiome and the central nervous system), this 2021 paper focuses on the potential role of this microbiome-gut-brain axis (MGBA) in attention deficit/hyperactivity disorder (ADHD). Although ADHD is the most common neurodevelopmental disorder in children, the research on this association has been limited and variable. Thus, the purpose of this present review was to present the current evidence on the functioning of the MGBA in children with ADHD and explain how omega-3 polyunsaturated fatty acids (ω-3 PUFAs) play a particular role in this interaction. In addition, the authors explore the possibility of utilizing the gut microbiome as a therapeutic target for ADHD. This review covers the following topics: the diverse interplay between the gut microbiome and the central nervous system; the influence of the gut microbiota on the imbalance in omega-3 polyunsaturated fatty acids seen in ADHD; and the current literature on probiotic use in pediatric patients with ADHD. In addition, the paper addresses the altered composition of gut microbiota observed in children and adolescents with ADHD, and how this relates to irregular physiological processes linked with the disorder. Finally, the article examines the connection between the gut microbiome and the regulation of circadian rhythm since sleep disorders often accompany ADHD. [NPID: ADHD, attention deficit hyperactivity disorder, microbiome, microbiota, bacteria, probiotics, omega-3, fatty acids, PUFAs, children, adolescents]