Probiotic Add-on Therapy in the First-episode Schizophrenia: A Randomized Controlled Trial

Some evidence supports probiotics’ beneficial effects on clinical symptoms of patients with schizophrenia and relieving unwanted frequently associated side effects of antipsychotic drugs such as constipation, obesity, and metabolic disorders.

This study aimed to assess the effect of probiotic supplements on clinical psychiatry symptoms and metabolic indices in patients with schizophrenia.

First-episode schizophrenic patients were randomly assigned to probiotics and placebo groups in a randomized controlled trial that took 12 weeks. The primary outcomes were the brief psychiatric rating scale (BPRS) change scores and positive and negative syndrome scale (PANSS). The secondary outcomes were clinical global impression-improvement scale (CGI-S), blood pressure (BP), body mass index (BMI), lipid profiles, and fasting blood sugar (FBS).

A total of 62 patients were considered for the intention-to-treat analysis (mean age, 34.7 years; 23 women; 39 men). The results showed no significant differences in the primary objectives between the probiotic and placebo groups. In the probiotic group, subjects had lower levels of all biochemical variables (triglycerides, cholesterol, and FBS) compared to the subjects in the placebo group (standardized mean difference -4.3, -2.8, and -4.6, respectively; P<0.05).

We found that by adding probiotics to oral antipsychotics, BPRS or PANSS scores do not improve. However, Cohen’s d for biochemical variables showed a medium to large effect size. This study suggests probiotic supplementation may regulate and control triglycerides, cholesterol, and FBS levels. Future studies are recommended to demonstrate these findings in the confirmatory analysis.