In autism spectrum disorder (ASD), altered microbial microenvironment associated with behavioral phenotypes but not gastrointestinal (GI) symptoms. These findings were published in Brain Behavior and Immunity.
Patients (n=82) with ASD were enrolled from the National Taiwan University Hospital, and healthy control individuals (n=31) were enrolled from the community for this study. Behavioral symptoms were evaluated using the Child Behavior Checklist (CBCL), Social Responsiveness Scale (SRS), and Restricted, repetitive/stereotyped behaviors and interest (RRSBI). Researchers evaluated GI symptoms using the Gastrointestinal Symptom Severity Index (GSSI), and microbial microenvironment was assessed in stool samples.
The ASD and control groups were 100% and 100% male; had a mean age of 17.16±4.91 and 13.02±3.86 years (P <.001); BMI was 20.86±4.45 and 17.65±3.33 kg/m2 (P <.001); and full-scale intellectual quotient was 100.48±19.19 and 112.16±7.65 (P =.001), respectively.
The ASD group had higher SRS social communication, stereotyped behaviors, social awareness, social emotion, and total scores (all P <.001) and higher CBCL aggressive behavior, anxious or depressed behavior, attention problems, delinquent behavior, social problems, somatic complaints, thought problems, withdrawn, internal problems, external problems, and dysregulation profiles scores (all P ≤.008) compared with control individuals.
The groups did not differ for GSSI abdominal pain (P =.200) or epigastric pain (P =.307) scores, but the ASD group reported higher upper GI symptoms (P =.019) and bowel habits (P =.019) scores compared with control individuals.
The analysis of the microbial microenvironment indicated the ASD and control individuals had similar Simpson diversity index (P =.150), Pielou’s evenness index (P =.182), Shannon-Wiener diversity index (P =.210), whole tree phylogenetic diversity (P =.548), species richness (P =.563), and Goods coverage index (P =.639).
The ASD group was found to have higher Ruminococcaceae UCG 013 (P =.006), Ruminococcus torques group (P =.003), and Bacteroides plebeius DSM 17135 (P =.015) and lower Erysipelotrichaceae UCG 003 (P =.025) and Parasutterella (P <.001) relative abundances compared with control individuals.
The microbial community was correlated with social communication (r, 0.72; P <.001), withdrawn behavior (r, 0.72; P <.001), social behavior (r, 0.65; P =.002), anxious or depressed behavior (r, 0.63; P =.002), social awareness (r, 0.56; P =.003), aggressive behavior (r, 0.56; P =.003), social emotion (r, 0.53; P =.003), somatic complaints (r, -0.45; P =.038), delinquent behavior (r, -0.67; P =.002), and dysregulation profile (r, -0.62; P =.002) among the ASD group. No significant correlations were observed among control individuals.
No correlations with GI symptoms were observed among either group.
Study limitations include using gut microbial composition, which may not serve as a predictive biomarker for ASD; enrolling only male participants; and the cross-sectional design.
“The present study showed microbial profiles strongly associated with phenotypes such as social problems, thought problems, delinquent behavior, dysregulation profile, and somatic complaints,” the study authors wrote. “Interestingly, we did not find evidence that GI symptoms were associated with microbiota alteration in ASD. If replicated, our results suggest that there may be an upstream role of the gut microbiome in ASD-related psychopathology and emotional/behavioral problems, regardless of the status of comorbid GI symptoms.”
Chen Y-C, Lin H-Y, Chien Y, Tung Y-H, Ni Y-H, Gau SS-F. Altered gut microbiota correlates with behavioral problems but not gastrointestinal symptoms in individuals with autism. Brain Behav Immun. 2022;106:161-178. doi:10.1016/j.bbi.2022.08.015