Mental Disorders Linked to Crosstalk between The Gut Microbiome and The Brain.

Experimental neurobiology. 2020;29(6):403-416

Plain language summary

The gut microbiome may have a role in regular brain function and mental health and this review paper aimed to determine the mechanisms through which this may be possible. There are several mental health disorders that may be affected by the gut microbiome, major depressive disorder (MDD), anxiety disorder, autism spectrum disorder (ASD), Alzheimer’s disease (AD), and addiction. It appears that there is a correlation between a disordered gut microbiome (known as dysbiosis) and MDD, ASD and addiction. Anxiety symptoms in healthy individuals and cognitive deficits in individuals with AD have reportedly been improved with probiotics. How the gut microbiome communicates with the brain was also discussed with the enteric nervous system, vagus nerve, spinal chord, immune system and brain signalling molecules all being implicated as possible routes. Finally, the paper discussed the use of probiotics for the prevention or treatment of mental disorders, with Bifidobacteria, Lactobacillus and specifically L. reuteri, L. plantarum and L. helveticus all shown in animal models to improve aspects associated with mental disorders. Amongst the human research B. longum has been shown to relieve stress and increase cognitive function in healthy individuals. It was concluded that studies have elucidated a relationship between the gut microbiome and mental health through various routes of communication. Research should focus on how gut microbiome changes are involved in mental illness. This study could be used by healthcare professionals to further knowledge on the potential relationship between the gut microbiome and mental health.


Often called the second brain, the gut communicates extensively with the brain and vice versa. The conversation between these two organs affects a variety of physiological mechanisms that are associated with our mental health. Over the past decade, a growing body of evidence has suggested that the gut microbiome builds a unique ecosystem inside the gastrointestinal tract to maintain the homeostasis and that compositional changes in the gut microbiome are highly correlated with several mental disorders. There are ongoing efforts to treat or prevent mental disorders by regulating the gut microbiome using probiotics. These attempts are based on the seminal findings that probiotics can control the gut microbiome and affect mental conditions. However, some issues have yet to be conclusively addressed, especially the causality between the gut microbiome and mental disorders. In this review, we focus on the mechanisms by which the gut microbiome affects mental health and diseases. Furthermore, we discuss the potential use of probiotics as therapeutic agents for psychiatric disorders.

Lifestyle medicine

Fundamental Clinical Imbalances : Neurological ; Digestive, absorptive and microbiological
Patient Centred Factors : Mediators/Gut microbiota
Environmental Inputs : Microorganisms ; Mind and spirit
Personal Lifestyle Factors : Nutrition ; Psychological
Functional Laboratory Testing : Not applicable
Bioactive Substances : Probiotics

Methodological quality

Jadad score : Not applicable
Allocation concealment : Not applicable
Publication Type : Journal Article ; Review