The Gut Microbiome in Psychosis From Mice to Men: A Systematic Review of Preclinical and Clinical Studies

Abstract

The gut microbiome is rapidly becoming the focus of interest as a possible factor involved in the pathophysiology of neuropsychiatric disorders. Recent understanding of the pathophysiology of schizophrenia emphasizes the role of systemic components, including immune/inflammatory and metabolic processes, which are influenced by and interacting with the gut microbiome. Here we systematically review the current literature on the gut microbiome in schizophrenia-spectrum disorders and in their animal models. We found that the gut microbiome is altered in psychosis compared to healthy controls. Furthermore, we identified potential factors related to psychosis, which may contribute to the gut microbiome alterations. However, further research is needed to establish the disease-specificity and potential causal relationships between changes of the microbiome and disease pathophysiology. This can open up the possibility of. manipulating the gut microbiome for improved symptom control and for the development of novel therapeutic approaches in schizophrenia and related psychotic disorders.

Cerebrospinal Fluid Inflammatory Cytokine Levels in Patients With Major Psychiatric Disorders: A Multiplex Immunoassay Study

“…Fourth, CSF may not be the best biological sample for seeking cytokine abnormalities in patients with psychiatric disorders. Peripheral metabolic and microbiome alternations ( Aizawa et al, 2016 ; Rosenblat and McIntyre, 2017 ; Hidese et al, 2018 ; Horne and Foster, 2018 ; Kraeuter et al, 2020 ) may rather be more sensitive than central immunological disturbances to elucidate inflammatory changes in the pathogenesis of psychiatric disorders. Fifth, since general laboratory data about inflammatory status (e.g., CSF or plasma C-reactive protein levels) were not included, this study could not address systemic inflammation in patient groups.…”

Modulation of Gut Microbial Diversity through Non-Pharmaceutical Approaches to Treat Schizophrenia

“…Most widely used pharmacological treatments have not provided any evidence of substantial improvement and recovery in most people with chronic schizophrenia [ 23 ]. Instead, the use of antipsychotics has several side effects such as weight gain [ 45 ], diabetes mellitus [ 46 ], atherosclerosis [ 47 ], glucose metabolism dysregulation [ 48 ], and most importantly gut microbial dysbiosis [ 49 ]. The use of antibiotics and changing dietary habits are the main reasons for alteration in the gut microflora that is directly associated with modified levels of neurotransmitters and brain function [ 50 , 51 , 52 ] ( Figure 2 ).…”

Stress and the Role of the Gut–Brain Axis in the Pathogenesis of Schizophrenia: A Literature Review

“…The gut–brain axis and microbiome have potential roles implicated in schizophrenia pathogenesis [ 59 , 60 ]. Additionally, gut microbiome changes may contribute to schizophrenia pathophysiology and behavioral symptoms development [ 61 ]. Increasing evidence has shown that disorders such as schizophrenia are associated with gut microbiome imbalances [ 5 , 6 ].…”

“…Research on animal models has been used to discuss the possible effects of the gut microbiome on immune changes in the central nervous system and behavior, as well as their possible contributions to the pathophysiology of psychiatric disorders. Early life events may change the gut microbiome and can cause psychosis development later [ 61 ]. Early life stress can cause long term gut microbiome alterations, and may lead to neuronal malfunction and behavioral changes which have a role in psychiatric disorders.…”