The microbiota-gut-brain axis, which refers to the bidirectional communication pathway between gut bacteria and the central nervous system, has a profound effect on important brain processes, from the synthesis of neurotransmitters to the modulation of complex behaviors such as sociability and anxiety. Previous studies have revealed that the gut microbiota is potentially related to not only gastrointestinal disturbances, but also social impairment and repetitive behavior-core symptoms of autism spectrum disorder (ASD). Although studies have been conducted to characterize the microbial composition in patients with ASD, the results are heterogeneous. Nevertheless, it is clear that there is a difference in the composition of the gut microbiota between ASD and typically developed individuals, and animal studies have repeatedly suggested that the gut microbiota plays an important role in ASD pathophysiology. This possibility is supported by abnormalities in metabolites produced by the gut microbiota and the association between altered immune responses and the gut microbiota observed in ASD patients. Based on these findings, various attempts have been made to use the microbiota in ASD treatment. The results reported to date suggest that microbiota-based therapies may be effective for ASD, but largescale, well-designed studies are needed to confirm this.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social and behavioral impairments. Recent studies have suggested that gut microbiota play a critical role in ASD pathogenesis. Herein, we investigated the fecal microflora of Korean ASD children to determine gut microbiota profiles associated with ASD. Specifically, fecal samples were obtained from 54 children with ASD and 38 age-matched children exhibiting typical development. Systematic bioinformatic analysis revealed that the composition of gut microbiota differed between ASD and typically developing children (TDC). Moreover, the total amounts of short-chain fatty acids, metabolites produced by bacteria, were increased in ASD children. At the phylum level, we found a significant decrease in the relative Bacteroidetes abundance of the ASD group, whereas Actinobacteria abundance was significantly increased. Furthermore, we found significantly lower Bacteroides levels and higher Bifidobacterium levels in the ASD group than in the TDC group at the genus level. Functional analysis of the microbiota in ASD children predicted that several pathways, including genetic information processing and amino acid metabolism, can be associated with ASD pathogenesis. Although more research is needed to determine whether the differences between ASD and TDC are actually related to ASD pathogenesis, these results provide further evidence of altered gut microbiota in children with ASD, possibly providing new perspectives on the diagnosis and therapeutic approaches for ASD patients.

Purpose: Emergency department (ED) is a common treatment setting for adolescents with clinically serious self-harm. Here, we investigated the clinical characteristics and trends of adolescents with self-harm who visited the ED in one Korean university hospital. We also compared patients with a single ED visit to those with multiple ED visits to identify the risk factor of repeated visits. Materials and Methods: We retrospectively identified patients aged 12 to 18 years who presented to ED for self-harm from January 2015 to December 2019, based on electronic medical records. Self-harm included all thoughts and behaviors indicating intents to harm or hurt oneself, regardless of the degree of such attempt. Results: A total of 168 individuals (male:female=31:137; average 15.99±1.64 years) presented to ED following 304 episodes (45 and 259 episodes in males and females, respectively). The number of episodes steeply increased between 2016 and 2019, and the overall number during the study showed an increasing trend (p=0.043). Repeated ED visitors with self-harm showed more history of psychiatric treatment/admission (58.3% vs. 85.4%, p=0.002; 14.2% vs. 43.9%, p<0.001), history of child abuse (32.3% vs. 53.7%, p=0.013), and familial psychiatric history (13.4% vs. 31.7%, p=0.008) compared to those with a single visit. Conclusion: Among Korean adolescents, the number of ED visits and repetition of ED visits for self-harm is on the rise. For adolescents presenting to ED with self-harm, the history of psychiatric treatment/admission, child abuse, and familial psychiatric history should be properly obtained to identify the risk for multiple ED visits.

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