A Systematic Review of the Effect of Probiotic Supplementation on Schizophrenia Symptoms

Abstract

Background: Derangements of the gut microbiome have been linked to increased systemic inflammation and central nervous system disorders, including schizophrenia. This systematic review thus aimed to investigate the hypothesis that probiotic supplementation improves schizophrenia symptoms. Methods: By using the keywords (probiotic OR gut OR microbiota OR microbiome OR yogurt OR yoghurt OR lactobacillus OR bifidobacterium) AND (schizophrenia OR psychosis), a preliminary search of the PubMed, Medline, Embase, Google Scholar, ClinicalTrials.gov, Clinical Trials Register of the Cochrane Collaboration Depression, Anxiety and Neurosis Group (CCDANTR), and Cochrane Field for Complementary Medicine databases yielded 329 papers published in English between January 1, 1960 and May 1, 2018. Attempts were made to search grey literature as well. Results: Three clinical studies were reviewed, comparing the use of probiotics to placebo controls. Applying per-protocol analysis and a fixed-effects model, there was no significant difference in schizophrenia symptoms between the group that received probiotic supplementation and the placebo group post-intervention as the standardized mean difference was –0.0884 (95% CI –0.380 to 0.204, p = 0.551). Separate analyses were performed to investigate the effect of probiotic supplementation on positive or negative symptoms of schizophrenia alone. In both instances, no significant difference was observed as well. Conclusion: Based on current evidence, limited inferences can be made regarding the efficacy of probiotics in schizophrenia. Although probiotics may have other benefits, for example to regulate bowel movement and ameliorate the metabolic effects of antipsychotic medications, the clinical utility of probiotics in the treatment of schizophrenia patients remains to be validated by future clinical studies.

Probiotics and the Microbiota-Gut-Brain Axis: Focus on Psychiatry

“…For schizophrenia, there are three RCTs, which were already systematically reviewed by Ng et al They did not find a significant difference in schizophrenia symptoms between probiotic and placebo groups postintervention when applying a per-protocol analysis and a fixed effects model [82].…”

Gut microbes in neurocognitive and mental health disorders

“…Human studies found patients treated with either risperidone or olanzapine had altered levels of Lachnospiraceae, Akkermansia, and Sutterella compared to controls [135]. A systematic review highlighted the limited evidence about the efficacy of probiotics in schizophrenia [136]. More research will be needed to better understand about GM manipulation in the treatment of schizophrenia.…”

Microbiota-Orientated Treatments for Major Depression and Schizophrenia

“…We have published a meta-analysis suggesting that patients with irritable bowel syndrome were at higher risk of major depression [37], confirming the potential causal or bilateral relationship between microbiota disturbances and major depression. Several studies have shown microbiota disturbances in patients with major depression; these disturbances are summarized in Table 1 [38][39][40][41][42][43][44][45][46][47][48][49][50]. Probiotics yielded small but significant effects for depression (d = −0.24, p < 0.01) and anxiety (d = −0.10, p = 0.03).…”