Background: As more animal studies start to disentangle pathways linking the gut microbial ecosystem and neurobehavioral traits, human studies have grown rapidly. Many have since investigated the bidirectional communication between the gastrointestinal tract and the central nervous system, specifically on the effects of microbial composition on the brain and development. Methods: Our review at the initial stage aimed to evaluate literature on gut microbial alterations in pediatric neurobehavioral conditions. We searched five literature databases (Embase, PubMed, PsychInfo, Scopus, and Medline) and found 4489 published work. As the mechanisms linking gut microbiota to these conditions are divergent, the scope of this review was narrowed to focus on describing gut dysbiosis in children with autism spectrum disorder (ASD). Results: Among the final 26 articles, there was a lack of consistency in the reported gut microbiome changes across ASD studies, except for distinguishable patterns, within limits, for Prevotella, Firmicutes at the phylum level, Clostridiales clusters including Clostridium perfringens, and Bifidobacterium species. Conclusions: These results were inadequate to confirm a global microbiome change in children with ASD and causality could not be inferred to explain the etiology of the behaviors associated with ASD. Mechanistic studies are needed to elucidate the specific role of the gut microbiome in the pathogenesis of ASD.

WHAT'S KNOWN ON THIS SUBJECT: Approximately 50% of children diagnosed with attention-deficit/hyperactivity disorder (ADHD) at ,7 years of age in the community do not meet criteria for ADHD over time. There is a need to examine predictors of diagnostic stability in young children with ADHD. WHAT THIS STUDY ADDS:Predictors of diagnostic stability from early to middle childhood include child' s baseline externalizing and internalizing symptoms, parental history of psychopathology, and socioeconomic status. These predictors may guide treatment planning at the time of ADHD diagnosis. abstract OBJECTIVES: The goals of this study were (1) to provide estimates of diagnostic stability for a sample of young children diagnosed with attention-deficit/hyperactivity disorder (ADHD) after undergoing comprehensive multidisciplinary assessments and (2) to identify baseline child and family characteristics that predict diagnostic stability over time. METHODS:Children aged 3 to 6 years, 11 months consecutively diagnosed with ADHD after multidisciplinary consultations at a tertiary care clinic between 2003 and 2008 were recontacted in 2012 and 2013 (N = 120). At follow-up, the primary outcome was the proportion of children who continued to meet diagnostic criteria for ADHD. To identify predictors of diagnostic stability, logistic regression models were used. In addition, a latent class model was used to independently classify subjects into distinct clusters. RESULTS:In this cohort, 70.4% of the children contacted at followup continued to meet diagnostic criteria for ADHD. Predictors of diagnostic stability included externalizing and internalizing symptoms at baseline, parental history of psychopathology, and family socioeconomic status. The latent class model independently identified 3 distinct profiles: (1) children who no longer met ADHD criteria; (2) children with persistent ADHD and high parental psychopathology; and (3) children with persistent ADHD and low family socioeconomic status. CONCLUSIONS:Young children who underwent comprehensive developmental and psychological assessments before receiving an ADHD diagnosis, had higher rates of diagnostic stability than in previous studies of community samples. Child and family factors that predict diagnostic stability have the potential to guide treatment planning for children diagnosed with ADHD before 7 years of age. Pediatrics