Pathogenesis of Pediatric Obsessive-compulsive Disorder: Based on the Microbiota-gut-brain Axis

We recruited outpatient children and adolescents with OCD confirmed by the Kiddie Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version (4th edition). The following inclusion and exclusion criteria were also applied: Inclusion Criteria: (1) 7-17 years old, (2) Y-BOCS score ≥16, (3) with or without a history of TD, (4) Drug-naïve or drug-free for 8 weeks, (5) Wechsler IQ score ≥ 80. Exclusion Criteria: * History of serious medical, neurological illness or other psychotic disorders other than OCD (tic disorder excepted). * Previous exposure to cognitive behavioral therapy (CBT) for OCD or TD. * serious suicide risk. * Has taken antibiotics, probiotics, prebiotics, corticosteroids, nonsteroidal anti-inflammatory drugs (NSAIDs), or immunosuppressants within the past 8 weeks. * Has a history of gastrointestinal diseases such as inflammatory bowel disease, irritable bowel syndrome, constipation, hemorrhoids, or a history of gastrointestinal surgery, or has a history of autoimmune diseases such as rheumatoid arthritis or systemic lupus erythematosus. * Participants with claustrophobic, heart pacemaker, mechanical heart valve, mechanical implant such as an aneurysm clip, hip replacement, or any other pieces of metal that have accidentally entered their body.