This study aims to evaluate the efficacy of fecal microbiota transplantation on the gastrointestinal symptoms, autistic symptoms and emotional behavior symptoms of patients with autism spectrum disorder, and investigate the relations between the brain-gut axis, cytokines and autism spectrum disorder. Fecal microbiota transplantation have the potentials to improve intestinal microbiota composition, regulate immunity, and then improve gastrointestinal symptoms, autistic symptoms, emotional behavior symptoms and sleep of children with autism spectrum disorder. Early intervention at school-age may even benefit development, improve cognition and prognosis.

Autism spectrum disorder (ASD) is an early neuropsychiatric developmental disorder. About 7-90% of patients with ASD have gastrointestinal problems which can relate to abnormal intestinal microbiota. The brain-gut axis can play a key role in the development of brain, and the interaction between microbiota and central nerve system can relate to the pathophysiology of ASD. Fecal Microbiota Transplantation (FMT) has just been used in the treatment of ASD in recent years. It has the potential to improve gastrointestinal, autistic, emotion and behavior symptoms of patients with ASD. Studies of its efficacy are still scarce, and no study has been conducted in Taiwan.

The purpose of this study is to treat patients with ASD by the fecal microbiota transplantation and evaluate its efficacy in gastrointestinal, autistic, emotion and behavior symptoms. It aims to prove the correlations between the brain-gut axis, intestinal microbiota, cytokines and ASD. FMT may improve and change the composition and diversity of intestinal microbiota of patients with ASD and modulate their immune reactions and subsequently improve gastrointestinal, autistic, emotion and behavior symptoms, as well as sleep. Early intervention by FMT in children with ASD may improve their cognition and hence result in better prognosis.

Study design: The investigators will recruit 45 patients with ASD and gastrointestinal problems, aged 6-30 years, who are willing to receive FMT and 1-year regular follow-up. The investigators will collect demographic data, blood and stool samples before and after the intervention, and analyze changes of intestinal microbiota and cytokines. The investigators will use subjective questionnaires to evaluate gastrointestinal, autistic, emotion and behavior symptoms, and objective measurements including actigraphy, intelligence and attention tests to evaluate changes in sleep and cognitive functions. The investigators will analyze the correlations between collected variables and compare the ASD group with the healthy control group at baseline to evaluate group differences. The investigators will evaluate the differences of the intervention group before and after FMT, and also compare the intervention group with the waiting list group, to evaluate the efficacy of FMT. Variables will be presented by mean and percentage. The investigators will use independent sample t-test or Chi-squared test for group comparison. The efficacy of FMT will be analyzed by dependent sample t-test or Wilcoxon signed-rank test, and the investigators will use Pearson correlation coefficient to analyze the correlations between variables.

Inclusion Criteria:

• Diagnosed by a child psychiatrist in line with DSM-5 Autism Spectrum Disorder
• Combined with gastrointestinal problems, any Gastrointestinal Symptoms Rating Scale score≧3.
• Age is between 7-30.
• Participants who are willing to participate in the study and sign the informed consent.

Exclusion Criteria:

• Cases where clinical assessment cannot cooperate with fecal microbiota transplantation and examination.
• Cases requiring antibiotics within 3 months before or after acceptance because of their physiological condition.
• Cases requiring long-term use of proton pump inhibitors due to their physiological conditions.
• Severe physical diseases, such as acute gastrointestinal diseases, severe malnutrition or underweight, immunodeficiency diseases, severe allergies or autoimmune diseases, brain injuries or severe organic brain diseases, will affect the evaluation of treatment results.
• Severe mental illness, such as schizophrenia, bipolar disorder, etc.
• Those who used probiotics one month before the case may affect the intestinal flora.
• Pregnancy.
• Cases that cannot understand the content of this research.
• Participants who are unwilling to participate in the study or refuse to sign the informed consent.
• Participants who are not suitable to include in this study, evaluate by PI or Co-PI.