The purpose of this study was to explore whether repeated oral fecal capsules could improve outcomes in patients with schizophrenia receiving conventional antipsychotic drugs. This study was divided into screening period (1 week) and treatment period (8 weeks). Subjects who met the inclusion criteria during the screening period entered the treatment period. During the treatment period, the patients were divided into two groups: oral fecal bacteria capsules + antipsychotics group; Oral placebo + antipsychotic group. During the follow-up period, both groups were treated with stable dose of antipsychotic drugs during the treatment period. Before and after the intervention, venous blood samples of patients were collected for routine tests such as liver and kidney function to determine the safety of treatment. The scale evaluated the improvement of patients' psychotic symptoms to determine the efficacy and safety of FMT combined with antipsychotics.

The main research content of this project is to observe the efficacy and safety of adjuvant FMT capsules in the treatment of schizophrenia by enrolling patients with schizophrenia and randomly administering FMT combined with antipsychotics or placebo combined with antipsychotics.

This is a multicenter, randomized, double-blind, placebo-controlled clinical trial. In this study, patients with schizophrenia were randomly divided into two groups. The first group was the experimental group, and FMT capsules (10^12 CFU/ capsule) were used in addition to conventional antipsychotic drugs. The other group, a control group, received a placebo pill with the same color, appearance and smell as the FMT capsules in addition to regular antipsychotic medication. Placebo capsules contain Lactobacillus probiotics for food use (10^12 CFU/ capsule). To observe the efficacy and safety of adjuvant FMT capsule in patients with schizophrenia.

The subjects (inpatients) were evaluated for meeting the eligibility requirements for this study according to the pre-specified inclusion and exclusion criteria, and demographic data (age, sex, marital status, educational level, employment, height and weight, smoking and drinking, and other general information as well as questionnaire assessment of eating habits) were collected. Improve laboratory examination (blood routine, liver function, kidney function and lipid), electrocardiogram and scale assessment.

Patients at the end of the screening period were randomly assigned to the experimental and control groups. Subjects will continue to receive FMT capsules or placebo capsules until the end of 8 weeks. During this period, both groups were given first-line atypical antipsychotics (clozapine, olanzapine, quintiapine, risperidone, aripiprazole, Ziprasidone, amsulapride, paliperidone, and paliperidone palmitate) recommended by current treatment guidelines, and added to the effective therapeutic dose within 1 week.

Benzodiazepines and drugs that ameliorate side effects of antipsychotics may be used during the study period. Antidepressants and mood stabilizers are prohibited. Transcranial magnetic stimulation and electronic biofeedback were allowed during the study, and non-convulsive electroconvulsive therapy was prohibited.

Inclusion Criteria:

• Aged from 18 to 65 years
• Patients with schizophrenia and a disease duration of 5 years or less are currently receiving first-line recommended antipsychotic medications
• The patients met the diagnostic criteria of schizophrenia in the 10th edition of the International Classification of Diseases (ICD-10)
• Positive and Negative Syndrome Scale (PANSS) : total score ≥60 (at least 3 positive items ≥3 or 3 negative items ≥3)
• Junior high school or above
• Subjects provided informed consent

Exclusion Criteria:

• Pregnant and lactating women
• Clinically significant or unstable medical diseases, including congestive heart failure, liver and kidney failure, cancer, immune and metabolic endocrine diseases
• Or hepatobiliary gastrointestinal diseases, abdominal pain, diarrhea (except functional constipation)
• Those who had acute or chronic infection, had taken anti-inflammatory drugs, cortisol hormones, and had received antibiotics in the past month
• Other neuropsychiatric disorders (patients with organic brain lesions, mental disorders and mental retardation caused by physical diseases or psychoactive substances)
• There were those with fixed drinking habits
• It is accompanied by intestinal diseases that seriously damage the intestinal barrier, such as inflammatory bowel disease, Crohn's disease, intestinal tuberculosis, ischemic bowel disease, radiation enteritis, and intestinal infectious diseases