The microbiome, immunity, and schizophrenia and bipolar disorder

Abstract

Schizophrenia and bipolar disorder are serious neuropsychiatric disorders of uncertain etiology. Recent studies indicate that immune activation may contribute to the etiopathogenesis of these disorders. Numerous studies in animal models indicate that the mucosal microbiome may influence cognition and behavior by altering the functioning of the immune system. It is thus likely that the microbiome plays a role in human psychiatric disorders. The study of immune alterations and the microbiome in schizophrenia and bipolar disorder is in its infancy. Two recent investigations of the oro-pharyngeal microbiota in schizophrenia found differences between cases and controls. Other studies have found increased gastrointestinal inflammation in schizophrenia and bipolar disorder based on measures of microbial translocation. Several studies have also found an association between the receipt of antibiotics and an increased incidence of psychiatric disorders, perhaps due to alterations in the microbiome. Studies to characterize the intestinal microbiome of individuals with these disorders are in progress. The ultimate test of the role of the microbiome and immune-mediated pathology in schizophrenia and bipolar disorder will come from clinical trials of therapeutic agents which alter gut microbiota or gastrointestinal inflammation. The successful development of such modalities would represent a novel strategy to prevent and treat serious psychiatric disorders.

Comprehensive comparison of monotherapies for psychiatric hospitalization risk in bipolar disorders

“…Consistent with our data, baseline substance use disorder, psychosis, and use of anticonvulsants and anxiolytics were previously reported to be risk factors for hospitalization in BD . The findings on the reduced risk of psychiatric hospitalizations for patients on antibiotics and non‐steroidal anti‐inflammatory drugs contribute to the evidence suggesting the importance of immune alterations, inflammation, and the microbiome in BDs …”

“…30 The findings on the reduced risk of psychiatric hospitalizations for patients on antibiotics and non-steroidal anti-inflammatory drugs contribute to the evidence suggesting the importance of immune alterations, inflammation, and the microbiome in BDs. 34 It is important to consider some additional limitations of the study, This finding can explain why AD monotherapy was the most commonly used treatment regimen and is of particular interest given the concerns about AD-induced risk of manic switch, 35 and potential contribution of the latter to treatment non-adherence. This highlights the challenges of the proper identification of BD in routine care settings and the negative sequelae of an incorrect diagnosis,…”

Adjunctive probiotic microorganisms to prevent rehospitalization in patients with acute mania: A randomized controlled trial

“…The principle of probiotic therapy is based on the fact that systemic inflammation is dependent to some extent on gastrointestinal inflammation and the composition of the bacterial flora of the gastrointestinal tract. Furthermore, the composition of the microbiome can modulate inflammation within the central nervous system through a series of interconnections which have been termed the gut‐brain axis . Previous studies have indicated that individuals whose intestinal tract contains potentially pathogenic anaerobic bacteria such as Bacteriodes fragilis and aerobic bacteria such as Escherichia coli are more likely to develop aberrant immune responses than individuals whose intestinal tract consists largely of non‐pathogenic anaerobic bacteria such as lactic acid‐producing bacteria ( Lactobacilli ) and non‐motile Gram‐positive bacteria such as Bifidobacteria .…”

Exploring the microbiome in health and disease

“…In contrast, similar administration of a combination of L. rhamnosus and B. animalis in patients diagnosed with schizophrenia saw no difference in the psychiatric symptom severity between the placebo and probiotics groups. 311 Contradictory results have emerged from depressed patients who consumed probiotics; while in some studies the use of probiotics seemed not to be associated with lower rates of depression, 318 in other studies the probiotic treatment produced a reduction in network-level neural reactivity to negative emotions, anxiolytic activity, suppression of psychological stress, and reduction of the negative thoughts associated with low mood. 343 …”