A Randomized, Single-blind, Parallel-controlled Clinical Trial of Puze Biological V9 Probiotic as an Adjunct Therapy for Children Aged 2-7 Years with Autism Spectrum Disorder

<i>Objective: </i>To evaluate the effects of Puze Biological V9 Probiotic (Bifidobacterium animalis subsp. lactis V9) as an adjunctive intervention on core symptoms, gastrointestinal symptoms, and gut microbiota in children aged 2-7 years with Autism Spectrum Disorder (ASD). <i>Methods: </i>A randomized, single-blind, parallel-controlled design was adopted. Sixty children with ASD (aged 2-7 years) who met the DSM-5 diagnostic criteria were randomly assigned in a 1:1 ratio to two groups: the control group (n=30) received conventional rehabilitation therapy (primarily Applied Behavior Analysis, ABA); the experimental group (n=30) received conventional rehabilitation therapy plus daily oral administration of Puze Biological V9 probiotic lyophilized powder (viable count ≥1×10^10 CFU/day). The intervention period was 3 months. The primary outcome measure was the change in total score on the Childhood Autism Rating Scale (CARS). Secondary outcome measures included scores on the Gastrointestinal Symptom Rating Scale (GSRS), the Social Responsiveness Scale (SRS), the Autism Behavior Checklist (ABC), fecal microbiota metagenomic analysis, and safety indicators. <i>Results: </i>After 3 months of intervention, the decrease in the total CARS score in the experimental group (12.3 ± 3.5 points) was significantly greater than that in the control group (8.1 ± 2.9 points) (P<0.01). The improvement in the total GSRS score and its sub-scores (abdominal pain, bloating, constipation, etc.) in the experimental group was also significantly superior to that in the control group (P<0.01). Improvements in SRS and ABC scale scores were also significant in the experimental group (P<0.05). Metagenomic analysis showed a significant increase in the abundance of beneficial bacteria such as Bifidobacterium and Lactobacillus, and a decrease in the abundance of potential harmful bacteria such as Clostridium in the gut of children in the experimental group. There was no statistically significant difference in the incidence of adverse events between the two groups. <i>Conclusion: </i>Based on conventional rehabilitation therapy, adjunctive use of Puze Biological V9 probiotic for 3 months can safely and effectively improve core behavioral symptoms and concomitant gastrointestinal dysfunction in children aged 2-7 years with ASD. Its effect may be related to regulating the structure of gut microbiota and optimizing the function of the "gut-brain axis". This study provides clinical evidence for the application of the domestic probiotic strain V9 in the adjunctive treatment of ASD.