Antipsychotics and the gut microbiome: olanzapine-induced metabolic dysfunction is attenuated by antibiotic administration in the rat

Causal link between gut microbiome and schizophrenia: a Mendelian randomization study

OBJECTIVE

Some observational studies have shown that gut microbiome is significantly changed in patients with schizophrenia. We aim to identify the genetic causal link between gut microbiome and schizophrenia.

METHODS

A two-sample Mendelian randomization (MR) study was used to evaluate the causal link between gut microbiome and schizophrenia with 28 gut microbiome-associated genetic instrumental variants chosen from recent MR reports and the largest schizophrenia genome-wide association studies (8-Apr-22 release).

RESULTS

Inverse variance weighted method showed that genetically increased Bacteroidales_S24-7 (per SD) resulted in increased risk of schizophrenia (OR = 1.110, 95% CI: [1.012-1.217], P  = 0.027). Similarly, genetically increased Prevotellaceae promoted schizophrenia risk (OR = 1.124, 95% CI: [1.030-1.228], P  = 0.009). However, genetically increased Lachnospiraceae reduced schizophrenia risk (OR = 0.878, 95% CI: [0.785-0.983], P  = 0.023). In addition, schizophrenia risk was also suppressed by genetically increased Lactobacillaceae (OR = 0.878, 95% CI: [0.776-0.994], P  = 0.040) and Verrucomicrobiaceae (OR = 0.860, 95% CI: [0.749-0.987], P  = 0.032). Finally, we did not find any significant results in the causal association of other 23 gut microbiome with schizophrenia.

CONCLUSION

Our analysis suggests that genetically increased Bacteroidales_S24-7 and Prevotellaceae promotes schizophrenia risk, whereas genetically increased Lachnospiraceae, Lactobacillaceae, and Verrucomicrobiaceae reduces schizophrenia risk. Thus, regulation of the disturbed intestinal microbiota may represent a new therapeutic strategy for patients with schizophrenia.

Associations of the Gut Microbiome With Treatment Resistance in Schizophrenia

Importance

There is growing interest in the role of gut microbiome composition in schizophrenia. However, lifestyle factors are often neglected, and few studies have investigated microbiome composition in treatment-resistant schizophrenia.

Objective

To explore associations between the gut microbiome and schizophrenia diagnosis, treatment resistance, clozapine response, and treatment-related adverse effects while adjusting for demographic and lifestyle factors.

Design, Setting, and Participants

In this case-control study of adults aged 20 to 63 years, stool samples and data on demographic characteristics, lifestyle, and medication use were collected and gut microbiome measures obtained using shotgun metagenomics. Participants with a schizophrenia diagnosis were referred through psychiatric inpatient units and outpatient clinics. Data were collected for 4 distinct groups: control individuals without a psychiatric diagnosis (past or present), individuals with treatment-responsive schizophrenia taking nonclozapine antipsychotic medications, clozapine-responsive individuals with treatment-resistant schizophrenia, and clozapine-nonresponsive individuals with treatment-resistant schizophrenia. Participants were recruited between November 2020 and November 2021. Control individuals were recruited in parallel through posters and online advertisements and matched for age, sex, and body mass index (BMI) to the individuals with schizophrenia. Participants were excluded if taking antibiotics in the past 2 months, if unable to communicate in English or otherwise follow study instructions, were pregnant or planning to become pregnant, or had any concomitant disease or condition making them unsuited to the study per investigator assessment. Data were analyzed from January 2022 to March 2023.

Main Outcomes and Measures

Omics relationship matrices, α and β diversity, and relative abundance of microbiome features.

Results

Data were collected for 97 individuals (71 [74%] male; mean [SD] age, 40.4 [10.3] years; mean [SD] BMI, 32.8 [7.4], calculated as weight in kilograms divided by height in meters squared). Significant microbiome associations with schizophrenia were observed at multiple taxonomic and functional levels (eg, common species: b2, 30%; SE, 13%; adjusted P = .002) and treatment resistance (eg, common species: b2, 27%; SE, 16%; adjusted P = .03). In contrast, limited evidence was found for microbiome associations with clozapine response, constipation, or metabolic syndrome. Significantly decreased microbial richness was found in individuals with schizophrenia compared to control individuals (t95 = 4.25; P < .001; mean [SD] for control individuals, 151.8 [32.31]; mean [SD] for individuals with schizophrenia, 117.00 [36.2]; 95% CI, 18.6-51.0), which remained significant after a covariate and multiple comparison correction. However, limited evidence was found for differences in β diversity (weighted UniFrac) for schizophrenia diagnosis (permutational multivariate analysis of variance [PERMANOVA]: R2, 0.03; P = .02), treatment resistance (R2, 0.02; P = .18), or clozapine response (R2, 0.04; P = .08). Multiple differentially abundant bacterial species (19) and metabolic pathways (162) were found in individuals with schizophrenia, which were primarily associated with treatment resistance and clozapine exposure.

Conclusions and Relevance

The findings in this study are consistent with the idea that clozapine induces alterations to gut microbiome composition, although the possibility that preexisting microbiome differences contribute to treatment resistance cannot be ruled out. These findings suggest that prior reports of microbiome alterations in individuals with chronic schizophrenia may be due to medication or lifestyle factors and that future studies should incorporate these variables in their design and interpretation.

A Possible Role of Akkermansia muciniphila in the Treatment of Olanzapine-Induced Weight Gain

Second-generation antipsychotics are mainly used in both acute and long-term treatment of major psychiatric disorders. Although better tolerated than first-generation antipsychotic drugs, they can frequently induce weight gain and metabolic disorders, of these, olanzapine is one of the drugs more likely to induce these side effects. There is consistent evidence of the role of gut microbiota in modulating the gut-brain axis with complex crosstalk with the host involving satiety signaling pathways, food intake behavior, and weight and metabolic regulation. Second-generation antipsychotics induce important gut microbiota modification thus contributing together with the central and peripheral receptors blockade mechanism to weight gain induction and metabolic impairment. These drugs can alter the composition of gut microbiota and induce dysbiosis, often reducing the concentration of Akkermansia muciniphila, a bacterium that is also decreased in patients with diabetes, obesity, metabolic syndrome, or chronic inflammatory diseases. Probiotic administration can be a safe and well-tolerated approach to modulate microbiota and offer an integrative strategy in psychiatric patients suffering antipsychotic side effects. Multiple strain probiotics and Akkermansia muciniphila alone have been administered both in mice models and in clinical populations demonstrating efficacy on antipsychotic-induced metabolic impairment and showing a contribution in reducing induced weight gain. Akkermansia muciniphila can improve several parameters altered by olanzapine administration, such as weight gain, insulin resistance, hyperglycemia, liver function, systemic inflammation, and gut barrier function. Although we do not have jet trials in the psychiatric population, this probiotic may be a complementary approach to treating olanzapine-induced weight gain and metabolic side effects.

Confounder or Confederate? The Interactions Between Drugs and the Gut Microbiome in Psychiatric and Neurological Diseases

The gut microbiome is emerging as an important factor in signaling along the gut-brain axis. The intimate physiological connection between the gut and the brain allows perturbations in the microbiome to be directly transmitted to the central nervous system and thereby contribute to psychiatric and neurological diseases. Common microbiome perturbations result from the ingestion of xenobiotic compounds including pharmaceuticals such as psychotropic drugs. In recent years, a variety of interactions between these drug classes and the gut microbiome have been reported, ranging from direct inhibitory effects on gut bacteria to microbiome-mediated drug degradation or sequestration. Consequently, the microbiome may play a critical role in influencing the intensity, duration, and onset of therapeutic effects, as well as in influencing the side effects that patients may experience. Furthermore, because the composition of the microbiome varies from person to person, the microbiome may contribute to the frequently observed interpersonal differences in the response to these drugs. In this review, we first summarize the known interactions between xenobiotics and the gut microbiome. Then, for psychopharmaceuticals, we address the question of whether these interactions with gut bacteria are irrelevant for the host (i.e., merely confounding factors in metagenomic analyses) or whether they may even have therapeutic or adverse effects.

The many faces of microbiota-gut-brain axis in autism spectrum disorder

The gut-brain axis is gaining more attention in neurodevelopmental disorders, especially autism spectrum disorder (ASD). Many factors can influence microbiota in early life, including host genetics and perinatal events (infections, mode of birth/delivery, medications, nutritional supply, and environmental stressors). The gut microbiome can influence blood-brain barrier (BBB) permeability, drug bioavailability, and social behaviors. Developing microbiota-based interventions such as probiotics, gastrointestinal (GI) microbiota transplantation, or metabolite supplementation may offer an exciting approach to treating ASD. This review highlights that RNA sequencing, metabolomics, and transcriptomics data are needed to understand how microbial modulators can influence ASD pathophysiology. Due to the substantial clinical heterogeneity of ASD, medical caretakers may be unlikely to develop a broad and effective general gut microbiota modulator. However, dietary modulation followed by administration of microbiota modulators is a promising option for treating ASD-related behavioral and gastrointestinal symptoms. Future work should focus on the accuracy of biomarker tests and developing specific psychobiotic agents tailored towards the gut microbiota seen in ASD patients, which may include developing individualized treatment options.

Gut microbiota composition in depressive disorder: a systematic review, meta-analysis, and meta-regression

Studies investigating gut microbiota composition in depressive disorder have yielded mixed results. The aim of our study was to compare gut microbiome between people with depressive disorder and healthy controls. We did a meta-analysis and meta-regression of studies by searching PubMed, Web of Science, Embase, Scopus, Ovid, Cochrane Library, ProQuest, and PsycINFO for articles published from database inception to March 07, 2022. Search strategies were then re-run on 12 March 2023 for an update. We undertook meta-analyses whenever values of alpha diversity and Firmicutes, Bacteroidetes (relative abundance) were available in two or more studies. A random-effects model with restricted maximum-likelihood estimator was used to synthesize the effect size (assessed by standardized mean difference [SMD]) across studies. We identified 44 studies representing 2091 patients and 2792 controls. Our study found that there were no significant differences in patients with depressive disorder on alpha diversity indices, Firmicutes and Bacteroidetes compared with healthy controls. In subgroup analyses with regional variations(east/west) as a predictor, patients who were in the West had a lower Chao1 level (SMD -0.42[-0.74 to -0.10]). Subgroup meta-analysis showed Firmicutes level was decreased in patients with depressive disorder who were medication-free (SMD -1.54[-2.36 to -0.72]), but Bacteroidetes level was increased (SMD -0.90[0.07 to 1.72]). In the meta-regression analysis, six variables cannot explain the 100% heterogeneity of the studies assessing by Chao1, Shannon index, Firmicutes, and Bacteroidetes. Depleted levels of Butyricicoccus, Coprococcus, Faecalibacterium, Fusicatenibacter, Romboutsia, and enriched levels of Eggerthella, Enterococcus, Flavonifractor, Holdemania, Streptococcus were consistently shared in depressive disorder. This systematic review and meta-analysis found that psychotropic medication and dietary habit may influence microbiota. There is reliable evidence for differences in the phylogenetic relationship in depressive disorder compared with controls, however, method of measurement and method of patient classification (symptom vs diagnosis based) may affect findings. Depressive disorder is characterized by an increase of pro-inflammatory bacteria, while anti-inflammatory butyrate-producing genera are depleted.

Impact of clozapine monotherapy on gut microbiota and metabolism in people with schizophrenia

Background

Clozapine is considered one of the most effective antipsychotic drugs, but it is most likely to cause metabolic abnormalities. Researchers have studied the causes of metabolic abnormalities caused by clozapine from multiple perspectives, but the reasons remain unclear.

Purpose

Characterize the gut microbiota of people with schizophrenia taking clozapine, exploring the association between gut microbiota and glucose lipid metabolic markers in schizophrenia patients taking clozapine.

Research design

Sixty-one long-term inpatients with schizophrenia in clozapine monotherapy were selected as study subjects. We got four subgroups by sex and the presence of metabolic syndrome.

Data analysis

16s analysis technology was applied at the genus level to determine the classification of gut microbiota. Then we compared the characteristics of gut microbiota and the association of gut microbiota with glucose lipid metabolic markers in each group.

Findings

We found differences in the diversity of gut microbiota among groups. The association between gut microbiota and glucose lipid metabolic markers was complicated. Gender was an important differentiating factor. Oscillibacter has a low abundance. However, it was the only genus associated with glycemic or lipids in each group. Among metabolic syndromes, Gemmiger was positively correlated with most lipids in females but negatively correlated in males, showing gender differences. In female non-metabolic syndromes, Bifidobacterium lost its probiotic character; instead, showing pathogenicity, which has strong positive correlations with fasting blood glucose and low-density lipoprotein but negative correlations with Apolipoprotein A1. Maybe schizophrenia, taking clozapine, and gender factors influenced the gut microbiota, which complicated our findings. The significance of the results remains to be determined by in-depth studies.

Longitudinal Gut Microbiota Dysbiosis Underlies Olanzapine-Induced Weight Gain

Olanzapine is one of the most effective medicines available for stabilizing schizophrenia spectrum disorders. However, it has been reported to show the greatest propensity for inducing body weight gain and producing metabolic side effects, which cause a great burden in patients with psychiatric disorders. Since the gut microbiota has a profound impact on the initiation and development of metabolic diseases, we conducted a longitudinal study to explore its role in olanzapine-induced obesity and metabolic abnormalities. Female Sprague-Dawley rats were treated with different doses of olanzapine, and metabolic and inflammatory markers were measured. Olanzapine significantly induced body weight gain (up to a 2.1-fold change), which was accompanied by hepatic inflammation and increased plasma triglyceride levels (up to a 2.9-fold change), as well as gut microbiota dysbiosis. Subsequently, fuzzy c-means clustering was used to characterize three clusters of longitudinal trajectories for microbial fluctuations: (i) genera continuing to increase, (ii) genera continuing to decrease, and (iii) genera temporarily changing. Among them, Enterorhabdus (r = 0.38), Parasutterella (r = 0.43), and Prevotellaceae UCG-001 (r = 0.52) positively correlated with body weight gain. In addition, two MetaCyc metabolic pathways were identified as associated with olanzapine-induced body weight gain, including the superpathway of glucose and xylose degradation and the superpathway of l-threonine biosynthesis. In conclusion, we demonstrate that olanzapine can directly alter the gut microbiota and rapidly induce dysbiosis, which is significantly associated with body weight gain. This may suggest gut microbiota targets in future studies on metabolic abnormalities caused by olanzapine. IMPORTANCE Olanzapine is one of the most effective second-generation antipsychotics for stabilizing schizophrenia spectrum disorders. However, olanzapine has multiple drug-induced metabolic side effects, including weight gain. This study provides insight to the gut microbiota target in olanzapine-induced obesity. Specifically, we explored the longitudinal gut microbiota trajectories of female Sprague-Dawley rats undergoing olanzapine treatment. We showed that olanzapine treatment causes a dynamic alteration of gut microbiota diversity. Additionally, we identified three genera, Parasutterella, Enterorhabdus, and Prevotellaceae UCG-001, that may play an important role in olanzapine-induced obesity. In this case, the supply or removal of specific elements of the gut microbiota may represent a promising avenue for treatment of olanzapine-related metabolic side effects.

Profiles and diagnostic value of intestinal microbiota in schizophrenia patients with metabolic syndrome

Aims/hypothesis

It is widely thought that the intestinal microbiota plays a significant role in the pathogenesis of metabolic disorders. However, the gut microbiota composition and characteristics of schizophrenia patients with metabolic syndrome (MetS) have been largely understudied. Herein, we investigated the association between the metabolic status of mainland Chinese schizophrenia patients with MetS and the intestinal microbiome.

Methods

Fecal microbiota communities from 115 male schizophrenia patients (57 with MetS and 58 without MetS) were assessed by 16S ribosomal RNA gene sequencing. We assessed the variations of gut microbiome between both groups and explored potential associations between intestinal microbiota and parameters of MetS. In addition, the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) based on the KEGG database was used to predict the function of intestinal microbiota. We also conducted Decision Tree Analysis to develop a diagnostic model for the MetS in patients with schizophrenia based on the composition of intestinal microbiota.

Results

The fecal microbial diversity significantly differed between groups with or without MetS (α-diversity (Shannon index and Simpson index): p=0.0155, p=0.0089; β-diversity: p=0.001). Moreover, the microbial composition was significantly different between the two groups, involving five phyla and 38 genera (p<0.05). In addition, a significant correlation was observed between the metabolic-related parameters and abundance of altered microbiota including HDL-c (r2 = 0.203, p=0.0005), GLU (r2 = 0.286, p=0.0005) and WC (r2 = 0.061, p=0.037). Furthermore, KEGG pathway analysis showed that 16 signaling pathways were significantly enriched between the two groups (p<0.05). Importantly, our diagnostic model based on five microorganisms established by decision tree analysis could effectively distinguish between patients with and without MetS (AUC = 0.94).

Conclusions/interpretation

Our study established the compositional and functional characteristics of intestinal microbiota in schizophrenia patients with MetS. These new findings provide novel insights into a better understanding of this disease and provide the theoretical basis for implementing new interventional therapies in clinical practice.

Targeting the gut microbiome to control drug pharmacomicrobiomics: the next frontier in oral drug delivery

INTRODUCTION

The trillions of microorganisms that comprise the gut microbiome form dynamic bidirectional interactions with orally administered drugs and host health. These relationships can alter all aspects of drug pharmacokinetics and pharmacodynamics (PK/PD); thus, there is a desire to control these interactions to maximize therapeutic efficacy. Attempts to modulate drug-gut microbiome interactions have spurred advancements within the field of 'pharmacomicrobiomics' and are poised to become the next frontier of oral drug delivery.

AREAS COVERED

This review details the bidirectional interactions that exist between oral drugs and the gut microbiome, with clinically relevant case examples outlining a clear motive for controlling pharmacomicrobiomic interactions. Specific focus is attributed to novel and advanced strategies that have demonstrated success in mediating drug-gut microbiome interactions.

EXPERT OPINION

Co-administration of gut-active supplements (e.g. pro- and pre-biotics), innovative drug delivery vehicles, and strategic polypharmacy serve as the most promising and clinically viable approaches for controlling pharmacomicrobiomic interactions. Targeting the gut microbiome through these strategies presents new opportunities for improving therapeutic efficacy by precisely mediating PK/PD, while mitigating metabolic disturbances caused by drug-induced gut dysbiosis. However, successfully translating preclinical potential into clinical outcomes relies on overcoming key challenges related to interindividual variability in microbiome composition and study design parameters.

Microbiota-gut-brain axis mechanisms in the complex network of bipolar disorders: potential clinical implications and translational opportunities

Bipolar disorders (BD) represent a severe leading disabling mental condition worldwide characterized by episodic and often progressive mood fluctuations with manic and depressive stages. The biological mechanisms underlying the pathophysiology of BD remain incompletely understood, but it seems that there is a complex picture of genetic and environmental factors implicated. Nowadays, gut microbiota is in the spotlight of new research related to this kind of psychiatric disorder, as it can be consistently related to several pathophysiological events observed in BD. In the context of the so-called microbiota-gut-brain (MGB) axis, it is shown to have a strong influence on host neuromodulation and endocrine functions (i.e., controlling the synthesis of neurotransmitters like serotonin or mediating the activation of the hypothalamic-pituitary-adrenal axis), as well as in modulation of host immune responses, critically regulating intestinal, systemic and brain inflammation (neuroinflammation). The present review aims to elucidate pathophysiological mechanisms derived from the MGB axis disruption and possible therapeutic approaches mainly focusing on gut microbiota in the complex network of BD. Understanding the mechanisms of gut microbiota and its bidirectional communication with the immune and other systems can shed light on the discovery of new therapies for improving the clinical management of these patients. Besides, the effect of psychiatric drugs on gut microbiota currently used in BD patients, together with new therapeutical approaches targeting this ecosystem (dietary patterns, probiotics, prebiotics, and other novelties) will also be contemplated.

The role of gut microbiota in depression: an analysis of the gut-brain axis

The gut-brain axis is a communication pathway that allows a two-way exchange of information between the microbiota of the gastrointestinal tract and the nervous system of humans. The vagus nerve, which is responsible for facilitating communication, provides support for this axis. The gut-brain axis is currently the subject of research, but studies into the diversity and stratification of the gut microbiota are just getting started. Researchers have discovered several positive trends by analyzing numerous studies examining the gut microbiota's impact on the effectiveness of SSRIs. It is common knowledge that a specific group of measurable, microbial markers has been recognized as being present in the feces of individuals suffering from depression. Specific bacterial species are a common denominator among therapeutic bacteria used to treat depression. It can also play a role in determining the severity of disease progression. Evidence that selective serotonin reuptake inhibitors (SSRIs) rely on the vagus nerve to exert their therapeutic effects has provided further support for the importance of the vagus nerve in the gut-brain axis, which is necessary for beneficial changes in the gut microbiota. This review will analyze the research linking gut microbiota to depression.

Emerging epigenetic dynamics in gut-microglia brain axis: experimental and clinical implications for accelerated brain aging in schizophrenia

Brain aging, which involves a progressive loss of neuronal functions, has been reported to be premature in probands affected by schizophrenia (SCZ). Evidence shows that SCZ and accelerated aging are linked to changes in epigenetic clocks. Recent cross-sectional magnetic resonance imaging analyses have uncovered reduced brain reserves and connectivity in patients with SCZ compared to typically aging individuals. These data may indicate early abnormalities of neuronal function following cyto-architectural alterations in SCZ. The current mechanistic knowledge on brain aging, epigenetic changes, and their neuropsychiatric disease association remains incomplete. With this review, we explore and summarize evidence that the dynamics of gut-resident bacteria can modulate molecular brain function and contribute to age-related neurodegenerative disorders. It is known that environmental factors such as mode of birth, dietary habits, stress, pollution, and infections can modulate the microbiota system to regulate intrinsic neuronal activity and brain reserves through the vagus nerve and enteric nervous system. Microbiota-derived molecules can trigger continuous activation of the microglial sensome, groups of receptors and proteins that permit microglia to remodel the brain neurochemistry based on complex environmental activities. This remodeling causes aberrant brain plasticity as early as fetal developmental stages, and after the onset of first-episode psychosis. In the central nervous system, microglia, the resident immune surveillance cells, are involved in neurogenesis, phagocytosis of synapses and neurological dysfunction. Here, we review recent emerging experimental and clinical evidence regarding the gut-brain microglia axis involvement in SCZ pathology and etiology, the hypothesis of brain reserve and accelerated aging induced by dietary habits, stress, pollution, infections, and other factors. We also include in our review the possibilities and consequences of gut dysbiosis activities on microglial function and dysfunction, together with the effects of antipsychotics on the gut microbiome: therapeutic and adverse effects, role of fecal microbiota transplant and psychobiotics on microglial sensomes, brain reserves and SCZ-derived accelerated aging. We end the review with suggestions that may be applicable to the clinical setting. For example, we propose that psychobiotics might contribute to antipsychotic-induced therapeutic benefits or adverse effects, as well as reduce the aging process through the gut-brain microglia axis. Overall, we hope that this review will help increase the understanding of SCZ pathogenesis as related to chronobiology and the gut microbiome, as well as reveal new concepts that will serve as novel treatment targets for SCZ.

Probiotics for the treatment of depression and its comorbidities: A systemic review

Depression is one of the most common psychiatric conditions, characterized by significant and persistent depressed mood and diminished interest, and often coexists with various comorbidities. The underlying mechanism of depression remain elusive, evidenced by the lack of an appreciate therapy. Recent abundant clinical trials and animal studies support the new notion that the gut microbiota has emerged as a novel actor in the pathophysiology of depression, which partakes in bidirectional communication between the gut and the brain through the neuroendocrine, nervous, and immune signaling pathways, collectively known as the microbiota-gut-brain (MGB) axis. Alterations in the gut microbiota can trigger the changes in neurotransmitters, neuroinflammation, and behaviors. With the transition of human microbiome research from studying associations to investigating mechanistic causality, the MGB axis has emerged as a novel therapeutic target in depression and its comorbidities. These novel insights have fueled idea that targeting on the gut microbiota may open new windows for efficient treatment of depression and its comorbidities. Probiotics, live beneficial microorganisms, can be used to modulate gut dysbiosis into a new eubiosis and modify the occurrence and development of depression and its comorbidities. In present review, we summarize recent findings regarding the MGB axis in depression and discuss the potential therapeutic effects of probiotics on depression and its comorbidities.

The Microbiota-Gut-Brain Axis: Psychoneuroimmunological Insights

There is growing interest in the role that the intestinal microbiota and the related autoimmune processes may have in the genesis and presentation of some psychiatric diseases. An alteration in the communication of the microbiota-gut-brain axis, which constitutes a communicative model between the central nervous system (CNS) and the gastro-enteric tract, has been identified as one of the possible causes of some psychiatric diseases. The purpose of this narrative review is to describe evidence supporting a role of the gut microbiota in psychiatric diseases and the impact of diet on microbiota and mental health. Change in the composition of the gut microbiota could determine an increase in the permeability of the intestinal barrier, leading to a cytokine storm. This could trigger a systemic inflammatory activation and immune response: this series of events could have repercussions on the release of some neurotransmitters, altering the activity of the hypothalamic-pituitary-adrenal axis, and reducing the presence of trophic brain factors. Although gut microbiota and psychiatric disorders seem to be connected, more effort is needed to understand the potential causative mechanisms underlying the interactions between these systems.

The regulatory effects of second-generation antipsychotics on lipid metabolism: Potential mechanisms mediated by the gut microbiota and therapeutic implications

Second-generation antipsychotics (SGAs) are the mainstay of treatment for schizophrenia and other neuropsychiatric diseases but cause a high risk of disruption to lipid metabolism, which is an intractable therapeutic challenge worldwide. Although the exact mechanisms underlying this lipid disturbance are complex, an increasing body of evidence has suggested the involvement of the gut microbiota in SGA-induced lipid dysregulation since SGA treatment may alter the abundance and composition of the intestinal microflora. The subsequent effects involve the generation of different categories of signaling molecules by gut microbes such as endogenous cannabinoids, cholesterol, short-chain fatty acids (SCFAs), bile acids (BAs), and gut hormones that regulate lipid metabolism. On the one hand, these signaling molecules can directly activate the vagus nerve or be transported into the brain to influence appetite via the gut-brain axis. On the other hand, these molecules can also regulate related lipid metabolism via peripheral signaling pathways. Interestingly, therapeutic strategies directly targeting the gut microbiota and related metabolites seem to have promising efficacy in the treatment of SGA-induced lipid disturbances. Thus, this review provides a comprehensive understanding of how SGAs can induce disturbances in lipid metabolism by altering the gut microbiota.

Clinical significance of microbiota changes under the influence of psychotropic drugs. An updated narrative review

Relationship between drugs and microbiota is bilateral. Proper composition thus function of microbiota is a key to some medications used in modern medicine. However, there is also the other side of the coin. Pharmacotherapeutic agents can modify the microbiota significantly, which consequently affects its function. A recently published study showed that nearly 25% of drugs administered to humans have antimicrobial effects. Multiple antidepressants are antimicrobials,. and antibiotics with proven antidepressant effects do exist. On the other hand, antibiotics (e.g., isoniaside, minocycline) confer mental phenotype changes, and adverse effects caused by some antibiotics include neurological and psychological symptoms which further supports the hypothesis that intestinal microbiota may affect the function of the central nervous system. Here we gathered comprehensively data on drugs used in psychiatry regarding their antimicrobial properties. We believe our data has strong implications for the treatment of psychiatric entities. Nevertheless the study of ours highlights the need for more well-designed trials aimed at analysis of gut microbiota function.

Gut microbiota and cardiac arrhythmia: a pharmacokinetic scope

BACKGROUND

Dealing with cardiac arrhythmia is a difficult challenge. Choosing between different anti-arrhythmic drugs (AADs) while being cautious about the pro-arrhythmic characteristics of some of these drugs and their diverse interaction with other drugs is a real obstacle.

MAIN BODY

Gut microbiota (GM), in our bodies, are now being considered as a hidden organ which can regulate our immune system, digest complex food, and secrete bioactive compounds. Yet, GM are encountered in the pathophysiology of arrhythmia and can affect the pharmacokinetics of AADs, as well as some anti-thrombotics, resulting in altering their bioavailability, therapeutic function and may predispose to some of their unpleasant adverse effects.

CONCLUSIONS

Knowledge of the exact role of GM in the pharmacokinetics of these drugs is now essential for better understanding of the art of arrhythmia management. Also, it will help deciding when to consider probiotics as an adjunctive therapy while treating arrhythmia. This should be discovered in the near future.

Modulation of hypothalamic AMPK phosphorylation by olanzapine controls energy balance and body weight

BACKGROUND

Second-generation antipsychotics (SGAs) are a mainstay therapy for schizophrenia. SGA-treated patients present higher risk for weight gain, dyslipidemia and hyperglycemia. Herein, we evaluated the effects of olanzapine (OLA), widely prescribed SGA, in mice focusing on changes in body weight and energy balance. We further explored OLA effects in protein tyrosine phosphatase-1B deficient (PTP1B-KO) mice, a preclinical model of leptin hypersensitivity protected against obesity.

METHODS

Wild-type (WT) and PTP1B-KO mice were fed an OLA-supplemented diet (5 mg/kg/day, 7 months) or treated with OLA via intraperitoneal (i.p.) injection or by oral gavage (10 mg/kg/day, 8 weeks). Readouts of the crosstalk between hypothalamus and brown or subcutaneous white adipose tissue (BAT and iWAT, respectively) were assessed. The effects of intrahypothalamic administration of OLA with adenoviruses expressing constitutive active AMPKα1 in mice were also analyzed.

RESULTS

Both WT and PTP1B-KO mice receiving OLA-supplemented diet presented hyperphagia, but weight gain was enhanced only in WT mice. Unexpectedly, all mice receiving OLA via i.p. lost weight without changes in food intake, but with increased energy expenditure (EE). In these mice, reduced hypothalamic AMPK phosphorylation concurred with elevations in UCP-1 and temperature in BAT. These effects were also found by intrahypothalamic OLA injection and were abolished by constitutive activation of AMPK in the hypothalamus. Additionally, OLA i.p. treatment was associated with enhanced Tyrosine Hydroxylase (TH)-positive innervation and less sympathetic neuron-associated macrophages in iWAT. Both central and i.p. OLA injections increased UCP-1 and TH in iWAT, an effect also prevented by hypothalamic AMPK activation. By contrast, in mice fed an OLA-supplemented diet, BAT thermogenesis was only enhanced in those lacking PTP1B. Our results shed light for the first time that a threshold of OLA levels reaching the hypothalamus is required to activate the hypothalamus BAT/iWAT axis and, therefore, avoid weight gain.

CONCLUSION

Our results have unraveled an unexpected metabolic rewiring controlled by hypothalamic AMPK that avoids weight gain in male mice treated i.p. with OLA by activating BAT thermogenesis and iWAT browning and a potential benefit of PTP1B inhibition against OLA-induced weight gain upon oral treatment.

Non-alcoholic fatty liver disease (NAFLD) and mental illness: Mechanisms linking mood, metabolism and medicines

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the world and one of the leading indications for liver transplantation. It is one of the many manifestations of insulin resistance and metabolic syndrome as well as an independent risk factor for cardiovascular disease. There is growing evidence linking the incidence of NAFLD with psychiatric illnesses such as schizophrenia, bipolar disorder and depression mechanistically via genetic, metabolic, inflammatory and environmental factors including smoking and psychiatric medications. Indeed, patients prescribed antipsychotic medications, regardless of diagnosis, have higher incidence of NAFLD than population norms. The mechanistic pharmacology of antipsychotic-associated NAFLD is beginning to emerge. In this review, we aim to discuss the pathophysiology of NAFLD including its risk factors, insulin resistance and systemic inflammation as well as its intersection with psychiatric illnesses.

Olanzapine-induced lipid disturbances: A potential mechanism through the gut microbiota-brain axis

Objective: Long-term use of olanzapine can induce various side effects such as lipid metabolic disorders, but the mechanism remains to be elucidated. The gut microbiota-brain axis plays an important role in lipid metabolism, and may be related to the metabolic side effects of olanzapine. Therefore, we explored the mechanism by which olanzapine-induced lipid disturbances through the gut microbiota-brain axis.

Methods: Sprague Dawley rats were randomly divided into two groups, which underwent subphrenic vagotomy and sham surgery. Then the two groups were further randomly divided into two subgroups, one was administered olanzapine (10 mg/kg/day) by intragastric administration, and the other was administered normal saline by intragastric administration (4 ml/kg/day) for 2 weeks. The final changes in lipid parameters, gut microbes and their metabolites, and orexin-related neuropeptides in the hypothalamus were investigated among the different groups.

Results: Olanzapine induced lipid disturbances as indicated by increased weight gain, elevated ratio of white adipose tissue to brown adipose tissue, as well as increased triglyceride and total cholesterol. Olanzapine also increased the Firmicutes/Bacteroides (F/B) ratio in the gut, which was even aggravated by subphrenic vagotomy. In addition, olanzapine reduced the abundance of short-chain fatty acids (SCFAs) metabolism related microbiome and 5-hydroxytryptamine (5-HT) levels in the rat cecum, and increased the gene and protein expression of the appetite-related neuropeptide Y/agouti-related peptide (NPY/AgRP) in the hypothalamus.

Conclusion: The abnormal lipid metabolism caused by olanzapine may be closely related to the vagus nerve-mediated gut microbiota-brain axis.

Potential diagnostic biomarkers for schizophrenia

Schizophrenia (SCH) is a complex and severe mental disorder with high prevalence, disability, mortality and carries a heavy disease burden, the lifetime prevalence of SCH is around 0.7%-1.0%, which has a profound impact on the individual and society. In the clinical practice of SCH, key problems such as subjective diagnosis, experiential treatment, and poor overall prognosis are still challenging. In recent years, some exciting discoveries have been made in the research on objective biomarkers of SCH, mainly focusing on genetic susceptibility genes, metabolic indicators, immune indices, brain imaging, electrophysiological characteristics. This review aims to summarize the biomarkers that may be used for the prediction and diagnosis of SCH.

Exploring the Correlation between Changes in Gut Microbial Community Diversity and Depression in Human Populations

Depression, also known as depressive disorder, is a group of psychosomatic affective disorders characterized by persistent and significantly depressed mood, delayed thinking, and cognitive impairment. The aim of this study was to explore the correlation between changes in gut microbial community diversity and depression to provide data on new strategies for the prevention and treatment of depression. In this study, we separated participants into a group of depressed patients and a healthy comparison group. We analyzed the gut microbial community structure of depressed patients and healthy comparisons using second-generation sequencing of the bacterial 16S RNA gene. There were significant differences in the gut microflora structure between patients with depression and healthy individuals. The gut flora alpha diversity index was significantly reduced in patients with depression compared to that in the healthy population. At the species level, the relative abundance of Coprococcus catus and Bacteroides barnesiae was significantly lower in the depressed group than that in the control group. The development of depression may be associated with a decrease in beneficial gut bacteria.

A dual treatment blocks alcohol binge-drinking relapse: Microbiota as a new player

RATIONALE

Gut microbiota communicates information to the brain. Some animals are born with a gut microbiota that predisposes to high alcohol consumption, and transplantation of fecal material from alcoholics to mice increases animal preference for ethanol. Alcohol-use-disorders are chronic conditions where relapse is the hallmark. A predictive animal model of relapse is the "alcohol deprivation effect" where ethanol re-access is allowed following chronic alcohol intake and a long alcohol deprivation. The present study evaluates the effect of gut microbiota modification on relapse, as an adjunct to N-acetylcysteine + Acetylsalicylic acid administration, which inhibits the alcohol-induced hyper-glutamatergic condition.

METHODS

Rats bred as heavy alcohol consumers (UChB) were allowed ethanol intake for one month, were deprived of alcohol for two-weeks and subsequently offered re-access to ethanol. Prior to ethanol re-access animals received orally either (i) vehicle-control, (ii) Lactobacillus-rhamnosus-GG after antibiotic treatment (LGG); (iii) N-acetylcysteine+Acetylsalicylic acid (NAC/ASA) or (iv) both treatments: LGG+ (NAC/ASA).

RESULTS

Marked binge drinking (1.75 g ethanol/kg in 60 min) and blood alcohol levels exceeding 80 mg/dl were observed in the control group upon ethanol-re-access. Lactobacillus-GG or (NAC+ASA) treatments inhibited alcohol intake by 66-80%. The combination of both treatments virtually suppressed (inhibition of 90%) the re-access binge-like drinking, showing additive effects. Treatment with NAC+ASA increased the levels of glutamate transporters xCT and GLT-1 in nucleus accumbens, while Lactobacillus-GG administration increased those of the dopamine transporter (DAT).

CONCLUSIONS

The administration of a well-accepted probiotic may be of value as an adjunct in the treatment of alcohol-use-disorders.

Diet-gut microbiota-epigenetics in metabolic diseases: From mechanisms to therapeutics

The prevalence of metabolic diseases, including obesity, dyslipidemia, type 2 diabetes mellitus (T2DM), and non-alcoholic fatty liver disease (NAFLD), is a severe burden in human society owing to the ensuing high morbidity and mortality. Various factors linked to metabolic disorders, particularly environmental factors (such as diet and gut microbiota) and epigenetic modifications, contribute to the progression of metabolic diseases. Dietary components and habits regulate alterations in gut microbiota; in turn, microbiota-derived metabolites, such as short-chain fatty acids (SCFAs), are influenced by diet. Interestingly, diet-derived microbial metabolites appear to produce substrates and enzymatic regulators for epigenetic modifications (such as DNA methylation, histone modifications, and non-coding RNA expression). Epigenetic changes mediated by microbial metabolites participate in metabolic disorders via alterations in intestinal permeability, immune responses, inflammatory reactions, and insulin resistance. In addition, microbial metabolites can trigger inflammatory immune responses and microbiota dysbiosis by directly binding to G-protein-coupled receptors (GPCRs). Hence, diet-gut microbiota-epigenetics may play a role in metabolic diseases. However, their complex relationships with metabolic diseases remain largely unknown and require further investigation. This review aimed to elaborate on the interactions among diet, gut microbiota, and epigenetics to uncover the mechanisms and therapeutics of metabolic diseases.

Probiotics Plus Dietary Fiber Supplements Attenuate Olanzapine-Induced Weight Gain in Drug-Naïve First-Episode Schizophrenia Patients: Two Randomized Clinical Trials

BACKGROUND AND HYPOTHESIS

Antipsychotic-induced weight gain is associated with alterations to the composition of the gut microbiota. The purpose of this study was to determine the effect of probiotics plus dietary fiber on antipsychotic-induced weight gain.

STUDY DESIGN

Two sequential, randomized clinical trials were conducted. In Study 1, 90 drug-naïve, first-episode schizophrenia patients were randomized to receive either olanzapine plus probiotics or olanzapine monotherapy for 12 weeks. In Study 2, 60 drug-naïve, first-episode schizophrenia patients were randomly assigned to receive either olanzapine plus probiotics and dietary fiber or olanzapine monotherapy for 12 weeks.

STUDY RESULTS

In Study 1, no significant differences in weight gain were observed between the two groups. The insulin resistance index (IRI) was lower in the olanzapine plus probiotics group compared with the olanzapine monotherapy group at week 12 (estimated mean difference, -0.65, [95% confidence interval (CI), -1.10 to -0.20]; p = .005). In Study 2, weight gain was lower in the probiotics plus dietary fiber group than in the olanzapine monotherapy group at week 12 (estimated mean difference -3.45 kg, [95% CI, -5.91 to -1.00]; p = .007). At week 12, IRI increased significantly in the olanzapine monotherapy group (mean, 1.74; standard deviation (SD) = 1.11, p < .001), but not in the olanzapine plus probiotics and dietary fiber group (mean 0.47, SD = 2.16, p = .35) with an estimated mean difference of -0.95 between the two groups [95% CI, -1.77 to -0.14]; p = .022).

CONCLUSIONS

These results provide support for the efficacy and safety of probiotics plus dietary fiber in attenuating antipsychotic-induced weight gain in drug-naïve, first-episode schizophrenia patients.

The effects of probiotics plus dietary fiber on antipsychotic-induced weight gain: a randomized clinical trial

Probiotics plus dietary fiber has demonstrated efficacy in improving metabolic abnormalities. However, the efficacy of probiotics and dietary fiber as well as their association with microbiota in attenuating antipsychotic-induced weight gain and metabolic disturbance remains poorly understood. Here we analyzed results from the double-blind, randomized, placebo-controlled study to compare and evaluate the effects of probiotics, dietary fiber, and their combination for antipsychotic-induced weight gain in patients with a severe mental disorder. We found that probiotics plus dietary fiber was significantly superior to probiotics alone, dietary fiber only, and the placebo for weight, BMI, and total cholesterol reduction; insulin resistance was worse in the placebo group, with significant increases during the 12-week treatment; probiotics plus dietary fiber significantly reduced weight and prevented further deterioration of metabolic disturbances; and probiotics or dietary fiber alone can prevent further weight gain. We further performed 16 S ribosomal RNA sequencing revealed an increased abundance of microbiota after probiotics plus dietary fiber treatment. Moreover, logistic regression analyses revealed that the higher richness of microbiota was associated with favorable weight loss. These findings suggested that probiotics and dietary fiber co-administration were safe and effective interventions to reduce weight gain in patients treated with antipsychotic medications.

Evidence for long-lasting alterations in the fecal microbiota following prenatal alcohol exposure

BACKGROUND

There is growing evidence that the gut microbiota can be shaped by early-life experiences/exposures, with long-term consequences for brain, behavior, and health. Changes in the gut microbiota have also been identified in neurodevelopmental disorders including Autism Spectrum Disorder and schizophrenia. In contrast, no studies to date have investigated whether the gut microbiota is altered in individuals with Fetal Alcohol Spectrum Disorder (FASD), the neurodevelopmental disorder that results from prenatal alcohol exposure (PAE). The current study was designed to assess the impact of PAE on the fecal microbiota.

METHODS

We used a rodent model in which pregnant Sprague-Dawley rats were provided with an EtOH-containing diet or a control diet throughout gestation. Fecal samples were collected from adult male and female animals and 16s rRNA sequencing was performed.

RESULTS

Overall, PAE rats showed greater richness of bacterial species, with community structure investigations demonstrating distinct clustering by prenatal treatment. In addition, prenatal treatment and sex-specific alterations were observed for many specific microbes. For example, in males, Bacteroides and Bifidobacterium, and in females, Faecalitalea and Proteus, differed in abundance between PAE and control rats.

CONCLUSIONS

Taken together, these results show for the first time that PAE has a long-lasting and sex-specific impact on the fecal microbiota. Further research is needed that considers fetal microbiota in the development of new interventions in FASD.

Does the gut microbiome mediate antipsychotic-induced metabolic side effects in schizophrenia?

INTRODUCTION

Second-generation antipsychotics (SGAs) are the most effective treatment for people with schizophrenia. Despite their effectiveness in treating psychotic symptoms, they have been linked to metabolic, cardiovascular and gastrointestinal side-effects. The gut microbiome has been implicated in potentiating symptoms of schizophrenia, response to treatment and medication-induced side effects and thus presents a novel target mediating second-generation antipsychotic-induced side effects in patients.

AREAS COVERED

This narrative review presents evidence from clinical and pre-clinical studies exploring the relationship between the gut microbiome, schizophrenia, second-generation antipsychotics and antipsychotic-induced side-effects. It also covers evidence for psychobiotic treatment as a potential supplementary therapy for people with schizophrenia.

EXPERT OPINION

The gut microbiome has the potential to mediate antipsychotic-induced side-effects in people with schizophrenia. Microbiome-focused treatments should be considered in combination with standard therapy in order to ameliorate debilitating drug-induced side effects, increase quality of life and potentially improve psychotic symptoms. Future studies should aim to collect not only microbiome data, but also metabolomic measures, dietary information and behavioral data.

Are We What We Eat? Impact of Diet on the Gut-Brain Axis in Parkinson's Disease

Parkinson’s disease is characterized by motor and non-motor symptoms, such as defects in the gut function, which may occur before the motor symptoms. To date, there are therapies that can improve these symptoms, but there is no cure to avoid the development or exacerbation of this disorder. Dysbiosis of gut microbiota could have a crucial role in the gut–brain axis, which is a bidirectional communication between the central nervous system and the enteric nervous system. Diet can affect the microbiota composition, impacting gut–brain axis functionality. Gut microbiome restoration through probiotics, prebiotics, synbiotics or other dietary means could have the potential to slow PD progression. In this review, we will discuss the influence of diet on the bidirectional communication between gut and brain, thus supporting the hypothesis that this disorder could begin in the gut. We also focus on how food-based therapies might then have an influence on PD and could ameliorate non-motor as well as motor symptoms.

Sex Differences in Fish Oil and Olanzapine Effects on Gut Microbiota in Diet-Induced Obese Mice

Children are prescribed second-generation antipsychotic (SGA) medications, such as olanzapine (OLZ) for FDA-approved and "off-label" indications. The long-term impact of early-life SGA medication exposure is unclear. Olanzapine and other SGA medications are known to cause excessive weight gain in young and adult patients, suggesting the possibility of long-term complications associated with the use of these drugs, such as obesity, diabetes, and heart disease. Further, the weight gain effects of OLZ have previously been shown to depend on the presence of gut bacteria and treatment with OLZ, which shifts gut bacteria toward an "obesogenic" profile. The purpose of the current study was to evaluate changes in gut bacteria in adult mice following early life treatment with OLZ and being fed either a high-fat diet or a high-fat diet supplemented with fish oil, which has previously been shown to counteract gut dysbiosis, weight gain, and inflammation produced by a high-fat diet. Female and male C57Bl/6J mice were fed a high fat diet without (HF) or with the supplementation of fish oil (HF-FO) and treated with OLZ from postnatal day (PND) 37-65 resulting in four groups of mice: mice fed a HF diet and treated with OLZ (HF-OLZ), mice fed a HF diet and treated with vehicle (HF), mice fed a HF-FO diet and treated with OLZ (HF-FO-OLZ), and mice fed a HF-FO diet and treated with vehicle (HF-FO). Following euthanasia at approximately 164 days of age, we determined changes in gut bacteria populations and serum LPS binding protein, an established marker of gut inflammation and dysbiosis. Our results showed that male HF-FO and HF-FO-OLZ mice had lower body weights, at sacrifice, compared to the HF group, with a comparable body weight across groups in female mice. HF-FO and HF-FO-OLZ male groups also exhibited lower serum LPS binding protein levels compared to the HF group, with no differences across groups in female mice. Gut microbiota profiles were also different among the four groups; the Bacteroidetes-to-Firmicutes (B/F) ratio had the lowest value of 0.51 in the HF group compared to 0.6 in HF-OLZ, 0.9 in HF-FO, and 1.1 in HF-FO-OLZ, with no differences in female mice. In conclusion, FO reduced dietary obesity and its associated inflammation and increased the B/F ratio in male mice but did not benefit the female mice. Although the weight lowering effects of OLZ were unexpected, FO effects persisted in the presence of olanzapine, demonstrating its potential protective effects in male subjects using antipsychotic drugs.

Gut microbiome in schizophrenia and antipsychotic-induced metabolic alterations: a scoping review

Schizophrenia (SCZ) is a severe mental disorder with high morbidity and lifetime disability rates. Patients with SCZ have a higher risk of developing metabolic comorbidities such as obesity and diabetes mellitus, leading to increased mortality. Antipsychotics (APs), which are the mainstay in the treatment of SCZ, increase the risk of these metabolic perturbations. Despite extensive research, the mechanism underlying SCZ pathophysiology and associated metabolic comorbidities remains unclear. In recent years, gut microbiota (GMB) has been regarded as a 'chamber of secrets', particularly in the context of severe mental illnesses such as SCZ, depression, and bipolar disorder. In this scoping review, we aimed to investigate the underlying role of GMB in the pathophysiology of SCZ and metabolic alterations associated with APs. Furthermore, we also explored the therapeutic benefits of prebiotic and probiotic formulations in managing SCZ and AP-induced metabolic alterations. A systematic literature search yielded 46 studies from both preclinical and clinical settings that met inclusion criteria for qualitative synthesis. Preliminary evidence from preclinical and clinical studies indicates that GMB composition changes are associated with SCZ pathogenesis and AP-induced metabolic perturbations. Fecal microbiota transplantation from SCZ patients to mice has been shown to induce SCZ-like behavioral phenotypes, further supporting the plausible role of GMB in SCZ pathogenesis. This scoping review recapitulates the preclinical and clinical evidence suggesting the role of GMB in SCZ symptomatology and metabolic adverse effects associated with APs. Moreover, this scoping review also discusses the therapeutic potentials of prebiotic/probiotic formulations in improving SCZ symptoms and attenuating metabolic alterations related to APs.

Metagenomic analysis reveals gut bacterial signatures for diagnosis and treatment outcome prediction in bipolar depression

BACKGROUND

We aimed to characterize gut microbial alterations in depressed patients with bipolar disorder (BD) following quetiapine monotherapy and explored its potential for disease diagnosis and outcome prediction.

METHODS

Fecal samples were obtained from 60 healthy individuals and 62 patients in acute depressive episodes. All patients received one-month quetiapine treatment after enrollment. The structure of gut microbiota was measured with metagenomic sequencing, and its correlation with clinical profiles and brain function as indicated by resting-state functional magnetic resonance imaging was analyzed. Random forest models based on bacterial species were constructed to distinguish patients from controls, and responders from non-responders, respectively.

RESULTS

BD patients displayed specific alterations in gut microbial diversity and composition. Quetiapine treatment increased the diversity of microbial communities and changed the composition. The abundance of Clostridium bartlettii was negatively associated with age, baseline depression severity, while positively associated with spontaneous neural oscillation in the hippocampus. Tree-based classification models for (1) patients and controls and (2) responders and non-responders showed an area under the curve of 0.733 and 0.800, respectively.

CONCLUSION

Our findings add new evidence to the existing literature regarding gut dysbiosis in BD and reveal the potential of microbe-based biomarkers for disease diagnosis and treatment outcome prediction.

Metformin acts on the gut-brain axis to ameliorate antipsychotic-induced metabolic dysfunction

Antipsychotic-induced metabolic dysfunction (AIMD) is an intractable clinical challenge worldwide. The situation is becoming more critical as second-generation antipsychotics (SGAs), to a great extent, have replaced the role of first-generation antipsychotics in managing major psychiatric disorders. Although the exact mechanisms for developing AIMD is intricate, emerging evidence has indicated the involvement of the microbiota-gut-brain axis in AIMD. SGAs treatment may change the diversity and compositions of intestinal flora (e.g., decreased abundance of Bacteroidetes and Akkermansia muciniphila, and increased Firmicutes). Short-chain fatty acids and other metabolites derived from gut microbiota, on the one hand, can regulate the activity of intestinal endocrine cells and their secretion of satiety hormones (e.g., glucagon-like peptide 1, peptide YY, cholecystokinin and ghrelin); on the other hand, can activate the vagus nerve or transport into the brain to exert a central modulation of foraging behaviors via binding to neuropeptide receptors. Interestingly, metformin, a classical antidiabetic agent, is capable of alleviating AIMD possibly by regulating the microbiota-gut-brain axis. That is, metformin can not only partially reverse the alterations of gut microbial communities due to SGAs treatment, but also play a positive role in rectifying the disturbances of peripheral and central satiety-related neuropeptides. Current evidence has indicated a promising role for metformin on ameliorating AMID, but further verifications in well-designed clinical trials are still warranted.

Assessment of the Effects of Dietary Vitamin D Levels on Olanzapine-Induced Metabolic Side Effects: Focus on the Endocannabinoidome-Gut Microbiome Axis

Vitamin D deficiency is associated with poor mental health and dysmetabolism. Several metabolic abnormalities are associated with psychotic diseases, which can be compounded by atypical antipsychotics that induce weight gain and insulin resistance. These side-effects may be affected by vitamin D levels. The gut microbiota and endocannabinoidome (eCBome) are significant regulators of both metabolism and mental health, but their role in the development of atypical antipsychotic drug metabolic side-effects and their interaction with vitamin D status is unknown. We studied the effects of different combinations of vitamin D levels and atypical antipsychotic drug (olanzapine) exposure on whole-body metabolism and the eCBome-gut microbiota axis in female C57BL/6J mice under a high fat/high sucrose (HFHS) diet in an attempt to identify a link between the latter and the different metabolic outputs induced by the treatments. Olanzapine exerted a protective effect against diet-induced obesity and insulin resistance, largely independent of dietary vitamin D status. These changes were concomitant with olanzapine-mediated decreases in Trpv1 expression and increases in the levels of its agonists, including various N-acylethanolamines and 2-monoacylglycerols, which are consistent with the observed improvement in adiposity and metabolic status. Furthermore, while global gut bacteria community architecture was not altered by olanzapine, we identified changes in the relative abundances of various commensal bacterial families. Taken together, changes of eCBome and gut microbiota families under our experimental conditions might contribute to olanzapine and vitamin D-mediated inhibition of weight gain in mice on a HFHS diet.

Effect of Bifidobacterium on olanzapine-induced body weight and appetite changes in patients with psychosis

RATIONALE

Gut microbiota plays an important role in host metabolism. Antipsychotic drugs can result in metabolic abnormalities. Probiotics may ameliorate the antipsychotic drug-induced metabolic abnormalities by regulating gut microbiota.

OBJECTIVE

To determine whether Bifidobacterium intervention can ameliorate olanzapine-induced weight increase.

METHODS

Enrolled patients were assigned to either the olanzapine or olanzapine plus Bifidobacterium group. The following were assessed: body weight, body mass index (BMI), appetite, latency to increased appetite, and baseline weight increase of more than 7%. All assessments were conducted at baseline and at 4, 8, and 12 weeks of treatment.

RESULTS

We enrolled 70 patients with schizophrenia or schizophrenic affective disorder, and 67 completed the study. Treatment for 4 weeks led to between-group differences in weight change (2.4 vs. 1.1 kg, p < 0.05) and BMI (0.9 vs. 0.4, p < 0.05). However, this difference disappeared at 8 and 12 weeks of treatment (both p > 0.05). The two groups did not differ in appetite increase at any time point (p > 0.05). The mean time from olanzapine initiation to appetite increase was also not significantly different between the two groups (t = 1.243, p = 0.220).

CONCLUSIONS

Probiotics may mitigate olanzapine-induced weight gain in the early stage of treatment and delay olanzapine-induced appetite increase.

A potential probiotic bacterium for antipsychotic-induced metabolic syndrome: mechanisms underpinning how Akkermansia muciniphila subtype improves olanzapine-induced glucose homeostasis in mice

BACKGROUND

Olanzapine (OLZ) is one of the most effective atypical antipsychotics but is associated with severe metabolic side effects, in which the gut microbiota plays an important role. Akkermansia muciniphila (A. muciniphila; Akk), a Gram-negative anaerobic bacterium in the intestine, can potentially improve metabolic syndrome.

OBJECTIVE

This study investigated the effect and underlying mechanisms of an A. muciniphila subtype (A. muciniphila^sub; Akk^sub) on OLZ-induced metabolic dysfunction in lean and obese mice.

METHODS

C57BL/6 female mice were fed a high-fat diet to induce obesity or normal chow for 8 weeks before OLZ treatment for 16 weeks. During the treatment period, mice in each group were orally administrated A. muciniphila^sub. Weight gain, glucose and lipid metabolism, and inflammation were evaluated.

RESULTS

A. muciniphila^sub decreased OLZ-related weight gain only at week 16 in lean mice and significantly alleviated OLZ-induced hyperglycemia irrespective of diet. This was accompanied by reduced levels of glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK)-key enzymes in hepatic gluconeogenesis-and OLZ-associated insulin resistance. Moreover, OLZ-induced increases in serum interleukin (IL)-6 and tumor necrosis factor (TNF)-α levels were improved by A. muciniphila^sub in both obese and lean mice. OLZ did not increase serum lipid levels or hepatic fat accumulation.

CONCLUSIONS

A. muciniphila^sub improves OLZ-related hyperglycemia via regulation of G6Pase and PEPCK levels and insulin resistance. Moreover, A. muciniphila^sub alleviates systemic inflammation caused by OLZ. A. muciniphila^sub is a promising probiotic treatment for OLZ-induced metabolic dysfunction.

Gut microbiome in adolescent depression

OBJECTIVES

To examine the association of major depressive disorder (MDD) and selective serotonin reuptake inhibitor (SSRI) use with gut microbiome in older adolescents and younger adults.

METHODS

Fifteen to 20-year-old participants within a month of starting an SSRI and unmedicated controls were enrolled in a longitudinal study. They underwent a diagnostic evaluation comprising self-completed and rater-administered questionnaires and clinical interview. They also provided a stool sample, which was stored at -80°C until DNA extraction. Microbial DNA was extracted with the MoBio PowerSoil kit, and the V4 region of the 16S rRNA was amplified and sequenced. Raw sequence data was processed with the LotuS pipeline. Only samples with no antibiotic exposure in the last 6 months and with >1000 quality filtered reads were included in the analysis.

RESULTS

160 participants (57.5% female, mean age 20.0±1.9 years, 29% taking SSRIs) were enrolled, comprising 110 MDD patients (60% in acute episode), 27 healthy controls, and 23 psychiatric controls. No significant group differences were observed in bacterial richness or alpha and beta diversity. Differential abundance analysis of bacterial taxa found no significant group differences at the phylum and genus levels. Neither being in a major depressive episode vs. remission nor using SSRIs was associated with differential bacterial composition.

CONCLUSIONS

In this sizeable sample of older adolescents, neither MDD nor SSRI use was associated with differences in gut bacterial microbiome. In this age group, the bi-directional interaction between the gut bacteria and brain may be more nuanced than in adults, requiring further investigation.

The role of microbiota-gut-brain axis in neuropsychiatric and neurological disorders

Emerging evidence indicates that the gut microbiota play a crucial role in the bidirectional communication between the gut and the brain suggesting that the gut microbes may shape neural development, modulate neurotransmission and affect behavior, and thereby contribute to the pathogenesis and/or progression of many neurodevelopmental, neuropsychiatric, and neurological conditions. This review summarizes recent data on the role of microbiota-gut-brain axis in the pathophysiology of neuropsychiatric and neurological disorders including depression, anxiety, schizophrenia, autism spectrum disorders, Parkinson's disease, migraine, and epilepsy. Also, the involvement of microbiota in gut disorders co-existing with neuropsychiatric conditions is highlighted. We discuss data from both in vivo preclinical experiments and clinical reports including: (1) studies in germ-free animals, (2) studies exploring the gut microbiota composition in animal models of diseases or in humans, (3) studies evaluating the effects of probiotic, prebiotic or antibiotic treatment as well as (4) the effects of fecal microbiota transplantation.

The role of the gut microbiome in the development of schizophrenia

Schizophrenia is a heterogeneous neurodevelopmental disorder involving the convergence of a complex and dynamic bidirectional interaction of genetic expression and the accumulation of prenatal and postnatal environmental risk factors. The development of the neural circuitry underlying social, cognitive and emotional domains requires precise regulation from molecular signalling pathways, especially during critical periods or "windows", when the brain is particularly sensitive to the influence of environmental input signalling. Many of the brain regions involved, and the molecular substrates sub-serving these domains are responsive to life-long microbiota-gut-brain (MGB) axis signalling. This intricate microbial signalling system communicates with the brain via the vagus nerve, immune system, enteric nervous system, enteroendocrine signalling and production of microbial metabolites, such as short-chain fatty acids. Preclinical data has demonstrated that MGB axis signalling influences neurotransmission, neurogenesis, myelination, dendrite formation and blood brain barrier development, and modulates cognitive function and behaviour patterns, such as, social interaction, stress management and locomotor activity. Furthermore, preliminary clinical studies suggest altered gut microbiota profiles in schizophrenia. Unravelling MGB axis signalling in the context of an evolving dimensional framework in schizophrenia may provide a more complete understanding of the neurobiological architecture of this complex condition and offers the possibility of translational interventions.

Innate gut microbiota predisposes to high alcohol consumption

Gut microbiota is known to be transferred from the mother to their offspring. This study determines whether the innate microbiota of rats selectively bred for generations as high alcohol drinkers play a role in their alcohol intake. Wistar-derived high-drinker UChB rats (intake 10-g ethanol/kg/day) administered nonabsorbable oral antibiotics before allowing access to alcohol, reducing their voluntary ethanol intake by 70%, an inhibition that remained after the antibiotic administration was discontinued. Oral administration of Lactobacillus rhamnosus Gorbach-Goldin (GG) induced the synthesis of FGF21, a vagal β-Klotho receptor agonist, and partially re-invoked a mechanism that reduces alcohol intake. The vagus nerve constitutes the main axis transferring gut microbiota information to the brain ("microbiota-gut-brain" axis). Bilateral vagotomy inhibited rat alcohol intake by 75%. Neither antibiotic treatment nor vagotomy affected total fluid intake. A microbiota-mediated marked inflammatory environment was observed in the gut of ethanol-naïve high-drinker rats, as gene expression of proinflammatory cytokines (TNF-α; IL-6; IL-1β) was significantly reduced by nonabsorbable antibiotic administration. Gut cytokines are known to activate the vagus nerve, while vagal activation induces pro-rewarding effects in nucleus accumbens. Both alcoholics and alcohol-preferring rats share a marked preference for sweet tastes-likely an evolutionary trait to seek sweet fermented fruits. Saccharin intake by UChB rats was inhibited by 75%-85% by vagotomy or oral antibiotic administration, despite saccharin-induced polydipsia. Overall, data indicate that the mechanisms that normally curtail heavy drinking are inhibited in alcohol-preferring animals and inform a gut microbiota origin. Whether it applies to other mammals and humans merits further investigation.

Nutritional and therapeutic approaches for protecting human gut microbiota from psychotropic treatments

Emerging evidence highlighted the essential role played by the microbiota-gut-brain axis in maintaining human homeostasis, including nutrition, immunity, and metabolism. Much recent work has linked the gut microbiota to many psychiatric and neurodegenerative disorders such as depression, schizophrenia, and Alzheimer's disease. Shared gut microbiota alterations or dysbiotic microbiota have been identified in these separate disorders relative to controls. Much attention has focused on the bidirectional interplay between the gut microbiota and the brain, establishing gut dysbiotic status as a critical factor in psychiatric disorders. Still, the antibiotic-like effect of psychotropic drugs, medications used for the treatment of these disorders, on gut microbiota is largely neglected. In this review, we summarize the current findings on the impact of psychotropics on gut microbiota and how their antimicrobial potency can trigger dysbiosis. We also discuss the potential therapeutic strategies, including probiotics, prebiotics, and fecal transplantation, to attenuate the dysbiosis related to psychotropics intake.

At the heart of the matter: Cardiovascular health challenges among incarcerated women

Many factors appear to contribute to an increased risk for cardiovascular disease (CVD) among incarcerated women. Imprisonment is associated with a bodyweight gain and an increased prevalence of overweight and obesity. Inadequate physical activity and unhealthy nutrition further contribute to this positive energy balance. Classical CVD risk factors are common, including hypertension, diabetes mellitus, metabolic syndrome, and smoking. Moreover, imprisonment is associated with an increased incidence of mental health issues, such as depression and anxiety, with coping mechanisms, including substance abuse, being frequently adopted. Specific attitudes in the correctional environment, including hunger strikes, bullying, abuse and solitary confinement, are effectors of cardiovascular and mental ill-health. Furthermore, the plethora of psychological stressors induces an accelerated aging process, paired with CVD risk. Communicable diseases, mainly human immunodeficiency virus, opportunistic infections and inadequate sunlight exposure increase cardiovascular dysregulation. Health care needs associated with the female sex are not always met, adding to the frustration and compromised well-being. All these factors act independently and cumulatively, increasing CVD risk among incarcerated women.

Voluntary binge-patterned alcohol drinking and sex-specific influences on monoamine-related neurochemical signatures in the mouse gut and brain

BACKGROUND

Altered monoamine (i.e., serotonin, dopamine, and norepinephrine) activity following episodes of alcohol abuse plays key roles not only in the motivation to ingest ethanol, but also physiological dysfunction related to its misuse. Although monoamine activity is essential for physiological processes that require coordinated communication across the gut-brain axis (GBA), relatively little is known about how alcohol misuse may affect monoamine levels across the GBA. Therefore, we evaluated monoamine activity across the mouse gut and brain following episodes of binge-patterned ethanol drinking.

METHODS

Monoamine and select metabolite neurochemical concentrations were analyzed by ultra-high-performance liquid chromatography in gut and brain regions of female and male C57BL/6J mice following "Drinking in the Dark" (DID), a binge-patterned ethanol ingestion paradigm.

RESULTS

First, we found that alcohol access had an overall small effect on gut monoamine-related neurochemical concentrations, primarily influencing dopamine activity. Second, neurochemical patterns between the small intestine and the striatum were correlated, adding to recent evidence of modulatory activity between these areas. Third, although alcohol access robustly influenced activity in brain areas in the mesolimbic dopamine system, binge exposure also influenced monoaminergic activity in the hypothalamic region. Finally, sex differences were observed in the concentrations of neurochemicals within the gut, which was particularly pronounced in the small intestine.

CONCLUSION

Together, these data provide insights into the influence of alcohol abuse and biological sex on monoamine-related neurochemical changes across the GBA, which could have important implications for GBA function and dysfunction.

Gut Microbiota and Bipolar Disorder: An Overview on a Novel Biomarker for Diagnosis and Treatment

The gut microbiota is the set of microorganisms that colonize the gastrointestinal tract of living creatures, establishing a bidirectional symbiotic relationship that is essential for maintaining homeostasis, for their growth and digestive processes. Growing evidence supports its involvement in the intercommunication system between the gut and the brain, so that it is called the gut-brain-microbiota axis. It is involved in the regulation of the functions of the Central Nervous System (CNS), behavior, mood and anxiety and, therefore, its implication in the pathogenesis of neuropsychiatric disorders. In this paper, we focused on the possible correlations between the gut microbiota and Bipolar Disorder (BD), in order to determine its role in the pathogenesis and in the clinical management of BD. Current literature supports a possible relationship between the compositional alterations of the intestinal microbiota and BD. Moreover, due to its impact on psychopharmacological treatment absorption, by acting on the composition of the microbiota beneficial effects can be obtained on BD symptoms. Finally, we discussed the potential of correcting gut microbiota alteration as a novel augmentation strategy in BD. Future studies are necessary to better clarify the relevance of gut microbiota alterations as state and disease biomarkers of BD.

The gut microbiome influences the bioavailability of olanzapine in rats

Background

The role of the gut microbiome in the biotransformation of drugs has recently come under scrutiny. It remains unclear whether the gut microbiome directly influences the extent of drug absorbed after oral administration and thus potentially alters clinical pharmacokinetics.

Methods

In this study, we evaluated whether changes in the gut microbiota of male Sprague Dawley rats, as a result of either antibiotic or probiotic administration, influenced the oral bioavailability of two commonly prescribed antipsychotics, olanzapine and risperidone.

Findings

The bioavailability of olanzapine, was significantly increased (1.8-fold) in rats that had undergone antibiotic-induced depletion of gut microbiota, whereas the bioavailability of risperidone was unchanged. There was no direct effect of microbiota depletion on the expression of major CYP450 enzymes involved in the metabolism of either drug. However, the expression of UGT1A3 in the duodenum was significantly downregulated. The reduction in faecal enzymatic activity, observed during and after antibiotic administration, did not alter the ex vivo metabolism of olanzapine or risperidone. The relative abundance of Alistipes significantly correlated with the AUC of olanzapine but not risperidone.

Interpretation

Alistipes may play a role in the observed alterations in olanzapine pharmacokinetics. The gut microbiome might be an important variable determining the systemic bioavailability of orally administered olanzapine. Additional research exploring the potential implication of the gut microbiota on the clinical pharmacokinetics of olanzapine in humans is warranted.

Funding

This research is supported by APC Microbiome Ireland, a research centre funded by Science Foundation Ireland (SFI), through the Irish Government's National Development Plan (grant no. 12/RC/2273 P2) and by Nature Research-Yakult (The Global Grants for Gut Health; Ref No. 626891).

The Gut Microbiome in Schizophrenia and the Potential Benefits of Prebiotic and Probiotic Treatment

The gut microbiome (GMB) plays an important role in developmental processes and has been implicated in the etiology of psychiatric disorders. However, the relationship between GMB and schizophrenia remains unclear. In this article, we review the existing evidence surrounding the gut microbiome in schizophrenia and the potential for antipsychotics to cause adverse metabolic events by altering the gut microbiome. We also evaluate the current evidence for the clinical use of probiotic and prebiotic treatment in schizophrenia. The current data on microbiome alteration in schizophrenia remain conflicting. Longitudinal and larger studies will help elucidate the confounding effect on the microbiome. Current studies help lay the groundwork for further investigations into the role of the GMB in the development, presentation, progression and potential treatment of schizophrenia.

The Burden of Antipsychotic-Induced Weight Gain and Metabolic Syndrome in Children

Antipsychotic medications are critical to child and adolescent psychiatry, from the stabilization of psychotic disorders like schizophrenia, bipolar disorder, and psychotic depression to behavioral treatment of autism spectrum disorder, tic disorders, and pediatric aggression. While effective, these medications carry serious risk of adverse events-most commonly, weight gain and cardiometabolic abnormalities. Negative metabolic consequences affect up to 60% of patients and present a major obstacle to long-term treatment. Since antipsychotics are often chronically prescribed beginning in childhood, cardiometabolic risk accumulates. An increased susceptibility to antipsychotic-induced weight gain (AIWG) has been repeatedly documented in children, particularly rapid weight gain. Associated cardiometabolic abnormalities include central obesity, insulin resistance, dyslipidemia, and systemic inflammation. Lifestyle interventions and medications such as metformin have been proposed to reduce risk but remain limited in efficacy. Furthermore, antipsychotic medications touted to be weight-neutral in adults can cause substantial weight gain in children. A better understanding of the biological underpinnings of AIWG could inform targeted and potentially more fruitful treatments; however, little is known about the underlying mechanism. As yet, modest genetic studies have nominated a few risk genes that explain only a small percentage of the risk. Recent investigations have begun to explore novel potential mechanisms of AIWG, including a role for gut microbiota and microbial metabolites. This article reviews the problem of AIWG and AP metabolic side effects in pediatric populations, proposed mechanisms underlying this serious side effect, and strategies to mitigate adverse impact. We suggest future directions for research efforts that may advance the field and lead to improved clinical interventions.