Gut feeling: randomized controlled trials of probiotics for the treatment of clinical depression: Systematic review and meta-analysis.

Viktoriya Nikolova, Syed Yawar Zaidi, Allan H Young, Anthony J Cleare, James M Stone

Journal: Therapeutic advances in psychopharmacology 2019;9():2045125319859963

PMID: 31263542

Plain Language Summary

Major depression is a common and complex illness that significantly diminishes quality of life. Currently, most pharmacological treatments target neurotransmitter activity in the brain and are known to have a delayed onset of effect as well as a range of side-effects. The aim of this study was to identify and synthesize all published data from randomized controlled trials (RCTs) on the efficacy of probiotics as treatment for depression in clinically depressed patients. This study is a systematic review of three studies. Within the three included RCTs, a total of 229 clinically depressed patients were randomized, with an average age of 36 years and a gender distribution of 76% female. Results indicate a non-significant difference in depressive symptoms between the probiotic and placebo groups post-intervention. Authors conclude that further larger studies in well-defined clinical populations are needed, both to determine the clinical utility of this novel treatment approach, and to investigate potential underlying mechanisms.

Abstract

BACKGROUND

Recently the gut microbiota has attracted significant interest in psychiatric research due to the observed bidirectional gut-brain communication. A growing body of evidence from preclinical work has suggested that probiotics may be effective in reducing stress and anxiety and alleviating low mood. It is unclear to what extent these effects are seen in clinical populations. We aimed to identify all published evidence on the efficacy of probiotics as treatment for depression in clinically depressed populations.

METHODS

Randomized controlled trials of patients with depression where probiotics were used as supplementary or standalone treatment were considered eligible. A literature search with the terms (* OR OR OR ) AND * was performed in PubMed and Web of Science. Data on study population characteristics, treatment effectiveness, tolerability and risk of bias were extracted from eligible studies. A random effects model was used for meta-analyses.

RESULTS

Only three studies met inclusion criteria (229 individuals randomized), two of which administered probiotics as a supplementary treatment to antidepressants and one as a standalone treatment. Upon removal of the latter study from the meta-analysis due to clinical heterogeneity, there was an overall positive effect of probiotics on depressive symptoms (standardized mean difference = 1.371, 95% confidence interval 0.130-2.613).

CONCLUSIONS

There is limited evidence for the efficacy of probiotics in depression at present, although there may be a beneficial effect of probiotics on depressive symptoms when administered in addition to antidepressants. Further studies are required to investigate this and explore potential mechanisms.

Address: Centre for Affective Disorders, Department of Psychological Medicine, Institute of Psychiatry, Psychology and Neuroscience, King's College, Denmark Hill, London, SE5 8AF, UK.; GKT School of Medical Education, King's College London, UK.; Institute of Psychiatry, Psychology and Neuroscience, Department of Psychological Medicine, King's College London, UK.; Institute of Psychiatry, Psychology and Neuroscience, Department of Neuroimaging, King's College London, UK.

DOI: 10.1177/2045125319859963