Altered composition and function of intestinal microbiota in autism spectrum disorders: a systematic review

Abstract

At present, the pathophysiology of autism spectrum disorder (ASD) remains unclear. Increasing evidence suggested that gut microbiota plays a critical role in gastrointestinal symptoms and behavioral impairment in ASD patients. The primary aim of this systematic review is to investigate potential evidence for the characteristic dysbiosis of gut microbiota in ASD patients compared with healthy controls (HCs). The MEDLINE, EMBASE, Web of Science and Scopus were systematically searched before March 2018. Human studies that compared the composition of gut microbiota in ASD patients and HCs using culture-independent techniques were included. Independent data extraction and quality assessment of studies were conducted according to PRISMA statement and Newcastle-Ottawa Scale. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) was used to infer biological functional changes of the shifted microbiota with the available data in four studies. Sixteen studies with a total sample size of 381 ASD patients and 283 HCs were included in this systematic review. The quality of the studies was evaluated as medium to high. The overall changing of gut bacterial community in terms of β-diversity was consistently observed in ASD patients compared with HCs. Furthermore, Bifidobacterium, Blautia, Dialister, Prevotella, Veillonella, and Turicibacter were consistently decreased, while Lactobacillus, Bacteroides, Desulfovibrio, and Clostridium were increased in patients with ASD relative to HCs in certain studies. This systematic review demonstrated significant alterations of gut microbiota in ASD patients compared with HCs, strengthen the evidence that dysbiosis of gut microbiota may correlate with behavioral abnormality in ASD patients. However, results of inconsistent changing also existed and further big-sampled well-designed studies are needed. Generally, as a potential mediator of risk factors, the gut microbiota could be a novel target for ASD patients in the future.

An approach to gut microbiota profile in children with autism spectrum disorder

“…Therefore, the present review expands upon the number of bacteria previously reported (Cao et al, 2013;Ding et al, 2017;Liu et al, 2019). Of note, the recent systematic review published by Liu et al (2019) reported on different articles from those included in the present systematic review, as they used different…”

“…Two studies found no differences in the GM composition of children with ASD (Gondalia et al ., ; Son et al ., ). Therefore, the present review expands upon the number of bacteria previously reported (Cao et al ., ; Ding et al ., ; Liu et al ., ). Of note, the recent systematic review published by Liu et al .…”

“…Of note, the recent systematic review published by Liu et al . () reported on different articles from those included in the present systematic review, as they used different inclusion/exclusion criteria such as the inclusion of articles that only analysed GM by culture‐independent methods or the time‐frame chosen (from inception to March 2018). In addition, some works have shown contradictory results regarding the nature and/or extent of GM abundance in children with ASD as discussed by Krajmalnik‐Brown et al .…”

“…It seems that a higher abundance of Clostridium ( Clostridium clostridioforme or Clostridium bolteae ) and Sutterella genera have been found in children with ASD and with GI problems, while lower levels of Prevotella genus have been found in children with ASD. A more recent systematic review up to 2018 reported elevated abundance of Proteobacteria , Lactobacillus , Bacteroides , Desulfovibrio and Clostridium , and decreased abundance of Bifidobacterium , Blautia , Dialister , Prevotella , Veillonella and Turicibacter in children with ASD compared to healthy controls (Liu et al ., ). There are also other studies and previous reviews in scientific literature about GM and ASD (Wang et al ., ; Cao et al ., ; De Angelis et al ., ; Krajmalnik‐Brown et al ., ; Andreo‐Martínez et al ., ; Martínez‐González and Andreo‐Martínez, ).…”

“…There are also other studies and previous reviews in scientific literature about GM and ASD (Wang et al ., ; Cao et al ., ; De Angelis et al ., ; Krajmalnik‐Brown et al ., ; Andreo‐Martínez et al ., ; Martínez‐González and Andreo‐Martínez, ). Although there have been advances in the study of GM in ASD (Ding et al ., ; Liu et al ., ), the latest review studies have not been conducted following the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines (Moher et al ., ) within the past 6 years. Consequently, this study aims to conduct an updated systematic review of the findings of the most common bacterial populations and their abundance in the GM of children with ASD compared to control groups.…”