The gut-brain relationship: Investigating the effect of multispecies probiotics on anxiety in a randomized placebo-controlled trial of healthy young adults

The (neuro)inflammatory system in anxiety disorders and PTSD: Potential treatment targets

Targeting the immune system has recently garnered attention in the treatment of stress- associated psychiatric disorders resistant to existing pharmacotherapeutics. While such approaches have been studied in considerable detail in depression, the role of (neuro)inflammation in anxiety-related disorders, or in anxiety as an important transdiagnostic symptom, is much less clear. In this review we first critically review clinical and in part preclinical evidence of central and peripheral immune dysregulation in anxiety disorders and post-traumatic stress disorder (PTSD) and briefly discuss proposed mechanisms of how inflammation can affect anxiety-related symptoms. We then give an overview of existing and potential future targets in inflammation-associated signal transduction pathways and discuss effects of different immune-modulatory drugs in anxiety-related disorders. Finally, we discuss key gaps in current clinical trials such as the lack of prospective studies involving anxiety patient stratification strategies based on inflammatory biomarkers. Overall, although evidence is rather limited so far, there is data to indicate that increased (neuro)inflammation is present in subgroups of anxiety disorder patients. Although exact identification of such immune subtypes of anxiety disorders and PTSD is still challenging, these patients will likely particularly benefit from therapeutic targeting of aspects of the inflammatory system. Different anti-inflammatory treatment approaches (microglia-directed treatments, pro-inflammatory cytokine inhibitors, COX-inhibitors, phytochemicals and a number of novel anti-inflammatory agents) have indeed shown some efficacy even in non-stratified anxiety patient groups and appear promising as novel alternative or complimentary therapeutic options in specific ("inflammatory") subtypes of anxiety disorder and PTSD patients.

Chronic starvation induces microglial cell depletion in an activity-based anorexia model

Anorexia nervosa (AN) is a severe psychiatric disease with a largely unknown pathophysiology. AN leads to reduced brain volume and a disbalance of the gut microbiome suggesting the involvement of the gut-brain-axis. Also, in the activity-based anorexia (ABA) animal model mimicking AN brain volume loss is observed. This study investigated the impact of chronic starvation on brain cell populations and evaluated the potential protective effects of omega-3 fatty acids (FA) and probiotics in rats. We used a chronic ABA model and provided daily oral supplementation of omega-3 FA and probiotics. Immunohistochemistry and qPCR were used to analyze GFAP-positive astrocytes, IBA1-positive microglia, OLIG1/2-positive oligodendrocytes, MAP2-positive neurons and Ki-67-positive proliferating cells in the cerebral cortex and corpus callosum. We found a significant reduction of astrocytes and microglia in all ABA groups, likely due to reduced proliferating cells. Reduced running wheel activity and reduced amount of food needed to sustain body weight were observed in animals with supplementation with omega-3 FA and probiotics but we did not observe alterations in brain cells that could be attributed to these supplementations. Our results indicate that glial cell depletion potentially underlies the diminished brain volume found in ABA rats. Omega-3 FA and probiotics show potential for reducing AN-related symptoms and merit further study as a therapeutic approach.

The Impact of Gut Microbiota on the Development of Anxiety Symptoms-A Narrative Review

The gut microbiota plays a key role in mental health, with growing evidence linking its composition to anxiety and depressive disorders. Research on this topic has expanded significantly in recent years. This review explores alterations in the gut microbiota of individuals with anxiety disorders and examines the potential therapeutic effects of probiotics. Background/Objectives: This review aims to analyze the alterations in gut microbiota composition in individuals with anxiety disorders and evaluate the potential therapeutic effects of probiotics in mitigating symptoms. By examining recent research, this study seeks to highlight the gut-brain connection and its implications for mental health interventions. Materials and Methods: A literature search was conducted in PubMed, Embase, CINAHL, and Google Scholar, focusing on studies investigating the relationship between gut microbiota and anxiety disorders, as well as the impact of probiotics on symptom severity. Results: The reviewed studies suggest that individuals with anxiety disorders often exhibit gut microbiota alterations, including reduced microbial diversity and a lower abundance of short-chain fatty acid-producing bacteria. Additionally, probiotics, particularly those from the Lactobacillus genus, may help alleviate anxiety symptoms by modulating gut microbiota composition. Conclusions: Gut dysbiosis appears to be closely linked to anxiety disorders, and probiotic interventions could represent a promising therapeutic avenue. However, further research is needed to clarify underlying mechanisms and optimize treatment strategies.

A menu for microbes: unraveling appetite regulation and weight dynamics through the microbiota-brain connection across the lifespan

Appetite, as the internal drive for food intake, is often dysregulated in a broad spectrum of conditions associated with over- and under-nutrition across the lifespan. Appetite regulation is a complex, integrative process comprising psychological and behavioral events, peripheral and metabolic inputs, and central neurotransmitter and metabolic interactions. The microbiota-gut-brain axis has emerged as a critical mediator of multiple physiological processes, including energy metabolism, brain function, and behavior. Therefore, the role of the microbiota-gut-brain axis in appetite and obesity is receiving increased attention. Omics approaches such as genomics, epigenomics, transcriptomics, proteomics, and metabolomics in appetite and weight regulation offer new opportunities for featuring obesity phenotypes. Furthermore, gut-microbiota-targeted approaches such as pre-, pro-, post-, and synbiotic, personalized nutrition, and fecal microbiota transplantation are novel avenues for precision treatments. The aim of this narrative review is 1) to provide an overview of the role of the microbiota-gut-brain axis in appetite regulation across the lifespan and 2) to discuss the potential of omics and gut microbiota-targeted approaches to deepen understanding of appetite regulation and obesity.

Can We Modulate Our Second Brain and Its Metabolites to Change Our Mood? A Systematic Review on Efficacy, Mechanisms, and Future Directions of "Psychobiotics"

Psychobiotics, live microorganisms that provide mental health by interacting with the gut microbiota, are emerging as a promising therapeutic option for psychiatric and neurodevelopmental disorders. Their effectiveness in addressing conditions such as depression, anxiety, insomnia, stress, autism spectrum disorder (ASD), and eating disorders were examined through a comprehensive analysis of existing studies up to the first half of 2024, based on data from reliable electronic databases. We found that psychobiotics can significantly reduce symptoms of various psychiatric disorders by influencing neurotransmitter levels, regulating the hypothalamic-pituitary-adrenal (HPA) axis, and improving gut barrier function through short-chain fatty acids (SCFAs) and other metabolites. However, several limitations were identified, including inconsistent study methodologies, small sample sizes, and a lack of data on long-term safety. Addressing these limitations through rigorous research is essential for establishing standardized protocols and fully confirming the therapeutic potential of psychobiotics. In conclusion, psychobiotics show great promise as complementary treatments for mental health conditions, but continued research is necessary to refine their application and integrate them into clinical practice effectively.

Beyond digestion: Exploring how the gut microbiota modulates human social behaviors

For a long time, traditional medicine has acknowledged the gut's impact on general health. Contemporary science substantiates this association through investigations of the gut microbiota, the extensive community of microorganisms inhabiting our gastrointestinal system. These microscopic residents considerably improve digestive processes, nutritional absorption, immunological function, and pathogen defense. Nevertheless, a variety of gastrointestinal and extra-intestinal disorders can result from dysbiosis, an imbalance of the microbial composition of the gut microbiota. A groundbreaking discovery is the gut-brain axis, a complex communication network that links the enteric and central nervous system (CNS). This bidirectional communication allows the brain to influence gut activities and vice versa, impacting mental health and mood disorders like anxiety and depression. The gut microbiota can influence this communication by creating neurotransmitters and short-chain fatty acids, among other biochemical processes. These factors may affect our mental state, our ability to regulate our emotions, and the hypothalamic-pituitary-adrenal (HPA) axis. This study aimed to explore the complex interrelationships between the brain and the gut microbiota. We also conducted a thorough examination of the existing understanding in the area of how microbiota affects social behaviors, including emotions, stress responses, and cognitive functions. We also explored the potential of interventions that focus on the connection between the gut and the brain, such as using probiotics to treat diseases of the CNS. This research opens up new possibilities for addressing mental health and neurological conditions in an innovative manner.

The Gut Microbiota-Brain Axis: A New Frontier in Alzheimer's Disease Pathology

Dr. Aloysius Alzheimer, a German neuropathologist and psychiatrist, recognized the primary instance of Alzheimer's disease (AD) for a millennium, and this ailment, along with its related dementias, remains a severe overall community issue related to health. Nearly fifty million individuals worldwide suffer from dementia, with Alzheimer's illness contributing to between 60 and 70% of the instances, estimated through the World Health Organization. In addition, 82 million individuals are anticipated to be affected by the global dementia epidemic by 2030 and 152 million by 2050. Furthermore, age, environmental circumstances, and inherited variables all increase the likelihood of acquiring neurodegenerative illnesses. Most recent pharmacological treatments are found in original hypotheses of disease, which include cholinergic (drugs that show affective cholinergic system availability) as well as amyloid-accumulation (a single drug is an antagonist receptor of Nmethyl D-aspartate). In 2020, the FDA provided approval on anti-amyloid drugs. According to mounting scientific data, this gut microbiota affects healthy physiological homeostasis and has a role in the etiology of conditions that range between obesity and neurodegenerative disorders like Alzheimer's. The microbiota-gut-brain axis might facilitate interconnection among gut microbes as well as the central nervous system (CNS). Interaction among the microbiota-gut system as well as the brain occurs through the "two-way" microbiota-gut-brain axis. Along this axis, the stomach as well as the brain develop physiologically and take on their final forms. This contact is constant and is mediated by numerous microbiota-derived products. The gut microbiota, for instance, can act as non-genetic markers to set a threshold for maintaining homeostasis or getting ill. The scientific community has conducted research and found that bowel dysbiosis and gastrointestinal tract dysregulation frequently occur in Alzheimer's disease (AD) patients. In this review, the effects of the microbiota- gut-brain axis on AD pathogenesis will be discussed.

The potential influence of microplastics on the microbiome and disease susceptibility in sea turtles

Microplastics (MPs) are particles with sizes of ≤5 mm formed when plastic materials break down. These contaminants are often found in marine environments, making it easy for sea turtles to ingest them and for their microbiome to be exposed. MPs can disrupt microbiome balance, leading to dysbiosis and making organisms more susceptible to diseases. Owing to the significance of these processes, it is crucial to dedicate research to studying the metabolic and genetic analysis of the gut microbiome in sea turtles. The objective of this study was to describe the effects of exposure to MPs on the gut microbiome of sea turtles, based on current knowledge. This review also aimed to explore the potential link between MP exposure and disease susceptibility in these animals. We show that the metabolites produced by the gut microbiome, such as short-chain fatty acids (SCFAs), polyamines, and polysaccharide A, can regulate the expression of host genes. Regulation occurs through various mechanisms, including histone acetylation, DNA methylation, and the modulation of cytokine gene expression. These processes are essential for preserving the integrity of the gut mucosa and enhancing the functionality of immune cells. Exposure to MPs disrupts the gut microbiome and alters gene expression, leading to immune system disturbances in sea turtles. This vulnerability makes turtles more susceptible to opportunistic microorganisms such as chelonid alphaherpesvirus 5 (ChAHV5), which is linked to the development of fibropapillomatosis (FP). Additionally, targeted dietary interventions or the use of live microorganisms such as probiotics can help restore microbial biodiversity and recover lost metabolic pathways. The goal of these interventions is to restore the functionality of the immune system in sea turtles undergoing rehabilitation at specialized centers. The gut microbiome plays a crucial role in sea turtle health, sparking discussions and investigations that can potentially lead to promising treatments for these animals.

Synbiotic supplementation may globally improve non-motor symptoms in patients with stable Parkinson's disease: results from an open label single-arm study

Gut microbiota changes and brain-gut-axis (BGA) dysregulation are common in people with Parkinson's Disease (PD). Probiotics and prebiotics are emerging as a potential therapeutic approach for PD patients. The aim of this paper was to assess the neurological and gastroenterological effects in PD patients with constipation after the administration of a synbiotic product, with a focus on behavioral and cognitive symptoms. We enrolled patients with stable PD who met diagnostic criteria for functional constipation and/or irritable bowel syndrome with constipation according to Rome IV Criteria. Patients received a synbiotic treatment (Enterolactis Duo, containing the probiotic strain Lacticaseibacillus paracasei DG and the prebiotic fiber inulin) for 12 weeks. A neurological and a gastroenterological evaluation were collected before and after the treatment. In addition, 16S rRNA gene profiling and short chain fatty acid quantification were performed to characterize the microbial ecosystem of fecal samples collected before (n = 22) and after (n = 9) the synbiotic administration. 30 patients were consecutively enrolled. After treatment, patients performed better in MDS-UPDRS part 1 (p = 0.000), SCOPA-AUT (p = 0.001), TAS-20 (p = 0.014), HAM-D (p = 0.026), DIFt (p = 0.003), PAS-A (p = 0.048). Gastroenterological evaluations showed improvements in PAC-SYM score (p < 0.001), number of complete bowel movement (p < 0.001) and BSFS (p < 0.001). After the synbiotic administration, we observed a significant increase in the abundance of the order Oscillospirales, as well as the Oscillospiraceae family and the species Faecalibacterium prausnitzii within this order in fecal samples. Synbiotic treatment demonstrates potential efficacy in ameliorating non-motor features in PD patients.

Exploring the gut-brain Axis: Potential therapeutic impact of Psychobiotics on mental health

One of the most challenging and controversial issues in microbiome research is related to gut microbial metabolism and neuropsychological disorders. Psychobiotics affect human behavior and central nervous system processes via the gut-brain axis, involving neuronal, immune, and metabolic pathways. They have therapeutic potential in the treatment of several neurodegenerative and neurodevelopmental disorders such as depression, anxiety, autism, attention deficit hyperactivity disorder, Alzheimer's disease, Parkinson's disease, schizophrenia, Huntington's disease, anorexia nervosa, and multiple sclerosis. However, the mechanisms underlying the interaction between psychobiotics and the abovementioned diseases need further exploration. This review focuses on the relationship between gut microbiota and its impact on neurological and neurodegenerative disorders, examining the potential of psychobiotics as a preventive and therapeutic approach, summarising recent research on the gut-brain axis and the potential beneficial effects of psychobiotics, highlighting the need for further research and investigation in this area.

Gut-Brain Axis: Investigating the Effects of Gut Health on Cognitive Functioning in Adults

INTRODUCTION

The gut-brain axis is a bidirectional communication network linking the gastrointestinal tract and the central nervous system via neuronal, hormonal, and antibody signaling pathways. Central to this connection is gut health, encompassing the balance and functionality of gut microbiota, which significantly impacts on mental and cognitive health. This study investigates the association between gut health and cognitive functioning in adults, highlighting the mechanisms by which gut microbiota influence brain health.

OBJECTIVE

To examine the effects of gut health on adult cognitive performance, with a focus on the processes by which gut microbiota impacts brain health.

METHODS

A quantitative cross-sectional study was conducted in Islamabad from January 2024 to April 2024, involving 140 adult participants. Data were collected using a comprehensive 16-item gut health questionnaire and the cognition self-assessment rating scale (C-SARS). The psychometric properties of these scales were assessed, and the data were analyzed using Statistical Product and Service Solutions (SPSS, v26; IBM SPSS Statistics for Windows, Armonk, NY). Analytical and descriptive statistics, including regression, chi-square, independent sample t-tests, and mean and standard deviation, were applied.

RESULTS

The study found moderate associations between gut health and cognitive performance, particularly in memory and processing speed (R² = 0.17, β = -1.9, p = 0.12 for general cognition; R² = 0.01, β = -0.98, p = 0.02 for memory; R² = 0.03, β = -0.18, p = 0.03 for processing speed). Gender and marital status differences were significant, with males exhibiting better gut health scores than females (M = 34.1, SD = 3.2 vs. M = 31.2, SD = 3.2, p = 0.00), and singles showing better cognitive performance compared to married individuals (M = 9.4, SD = 5.4 vs. M = 6.5, SD = 3.7, p = 0.03).

CONCLUSION

The study highlights significant associations between gut health and cognitive functions, suggesting that gut microbiota composition can influence cognitive performance. Gender and marital status differences underscore the need to consider individual differences in gut-brain axis research. Future studies should replicate these findings in larger samples and explore gut microbiota-targeted interventions for cognitive health enhancement.

Computational prediction of new therapeutic effects of probiotics

Probiotics are living microorganisms that provide health benefits to their hosts, potentially aiding in the treatment or prevention of various diseases, including diarrhea, irritable bowel syndrome, ulcerative colitis, and Crohn's disease. Motivated by successful applications of link prediction in medical and biological networks, we applied link prediction to the probiotic-disease network to identify unreported relations. Using data from the Probio database and International Classification of Diseases-10th Revision (ICD-10) resources, we constructed a bipartite graph focused on the relationship between probiotics and diseases. We applied customized link prediction algorithms for this bipartite network, including common neighbors, Jaccard coefficient, and Adamic/Adar ranking formulas. We evaluated the results using Area under the Curve (AUC) and precision metrics. Our analysis revealed that common neighbors outperformed the other methods, with an AUC of 0.96 and precision of 0.6, indicating that basic formulas can predict at least six out of ten probable relations correctly. To support our findings, we conducted an exact search of the top 20 predictions and found six confirming papers on Google Scholar and Science Direct. Evidence suggests that Lactobacillus jensenii may provide prophylactic and therapeutic benefits for gastrointestinal diseases and that Lactobacillus acidophilus may have potential activity against urologic and female genital illnesses. Further investigation of other predictions through additional preclinical and clinical studies is recommended. Future research may focus on deploying more powerful link prediction algorithms to achieve better and more accurate results.

The effects of micro- and nanoplastics on the central nervous system: A new threat to humanity?

Given the widespread production and use of plastics, poor biodegradability, and inadequate recycling, micro/nanoplastics (MNPs) have caused widespread environmental pollution. As a result, humans inevitably ingest MNPs through various pathways. However, there is still no consensus on whether exposure to MNPs has adverse effects on humans. This article aims to provide a comprehensive overview of the knowledge of MNPs and the potential mechanisms of their impact on the central nervous system. Numerous in vivo and in vitro studies have shown that exposure to MNPs may pass through the blood-brain barrier (BBB) and lead to neurotoxicity through impairments in oxidative and inflammatory balance, neurotransmitter alternation, nerve conduction-related key enzymes, and impact through the gut-brain axis. It is worth noting that MNPs may act as carriers and have more severe effects on the body when co-exposed with other substances. MNPs of smaller sizes cause more severe harm. Despite the scarcity of reports directly relevant to humans, this review brings together a growing body of evidence showing that exposure to MNPs disturbs neurons and has even been found to alter the memory and behavior of organisms. This effect may lead to further potential negative influence on the central nervous system and contribute to the development of other diseases such as central nervous system inflammation and Parkinson 's-like neurodegenerative disorders. There is a need further to investigate the threat of MNPs to human health.

Improving precision management of anxiety disorders: a Mendelian randomization study targeting specific gut microbiota and associated metabolites

Background

There is growing evidence of associations between the gut microbiota and anxiety disorders, where changes in gut microbiotas may affect brain function and behavior via the microbiota-gut-brain axis. However, population-level studies offering a higher level of evidence for causality are lacking. Our aim was to investigate the specific gut microbiota and associated metabolites that are closely related to anxiety disorders to provide mechanistic insights and novel management perspectives for anxiety disorders.

Method

This study used summary-level data from publicly available Genome-Wide Association Studies (GWAS) for 119 bacterial genera and the phenotype "All anxiety disorders" to reveal the causal effects of gut microbiota on anxiety disorders and identify specific bacterial genera associated with anxiety disorders. A two-sample, bidirectional Mendelian randomization (MR) design was deployed, followed by comprehensive sensitivity analyses to validate the robustness of results. We further conducted multivariable MR (MVMR) analysis to investigate the potential impact of neurotransmitter-associated metabolites, bacteria-associated dietary patterns, drug use or alcohol consumption, and lifestyle factors such as smoking and physical activity on the observed associations.

Results

Bidirectional MR analysis identified three bacterial genera causally related to anxiety disorders: the genus Eubacterium nodatum group and genus Ruminococcaceae UCG011 were protective, while the genus Ruminococcaceae UCG011 was associated with an increased risk of anxiety disorders. Further MVMR suggested that a metabolite-dependent mechanism, primarily driven by tryptophan, tyrosine, phenylalanine, glycine and cortisol, which is consistent with previous research findings, probably played a significant role in mediating the effects of these bacterial genera to anxiety disorders. Furthermore, modifying dietary pattern such as salt, sugar and processed meat intake, and adjusting smoking state and physical activity levels, appears to be the effective approaches for targeting specific gut microbiota to manage anxiety disorders.

Conclusion

Our findings offer potential avenues for developing precise and effective management approaches for anxiety disorders by targeting specific gut microbiota and associated metabolites.

Probiotics' Effects in the Treatment of Anxiety and Depression: A Comprehensive Review of 2014-2023 Clinical Trials

Changes in the gut microbiome can affect cognitive and psychological functions via the microbiota-gut-brain (MGB) axis. Probiotic supplements are thought to have largely positive effects on mental health when taken in sufficient amounts; however, despite extensive research having been conducted, there is a lack of consistent findings on the effects of probiotics on anxiety and depression and the associated microbiome alterations. The aim of our study is to systematically review the most recent literature of the last 10 years in order to clarify whether probiotics could actually improve depression and anxiety symptoms. Our results indicate that the majority of the most recent literature suggests a beneficial role of probiotics in the treatment of depression and anxiety, despite the existence of a substantial number of less positive findings. Given probiotics' potential to offer novel, personalized treatment options for mood disorders, further, better targeted research in psychiatric populations is needed to address concerns about the exact mechanisms of probiotics, dosing, timing of treatment, and possible differences in outcomes depending on the severity of anxiety and depression.

TGR5 deficiency-induced anxiety and depression-like behaviors: The role of gut microbiota dysbiosis

BACKGROUND AND PURPOSE

Anxiety and depression have been associated with imbalances in the gut microbiota and bile acid metabolism. Takeda G protein-coupled receptor 5 (TGR5), a bile acid receptor involved in metabolism, is influenced by the gut microbiota. This study aimed to investigate the relationship between anxiety, depression, and microbiota using TGR5 knockout mice.

METHODS

We employed the following methods: (1) Assessment of behavioral changes, (2) Measurement of 5-HT levels and protein expression, (3) Analysis of stool samples, (4) Utilization of gene sequencing and statistical analysis to identify microbial signatures, (5) Examination of correlations between microbial signatures and 5-HT levels, and (6) Fecal microbiota transplantation experiments of TGR5-/- mice.

RESULTS

The deletion of TGR5 was found to result in increased anxiety- and depression-like behaviors in mice. TGR5 knockout mice exhibited significant reductions in 5-hydroxytryptamine (5-HT) levels in both serum and hippocampus, accompanied by a decrease in the expression of 5-HT1A receptor in the hippocampus. Moreover, TGR5 deficiency was associated with a decrease in the species richness of the gut microbiota. Specifically, the gut microbiota compositions of TGR5 knockout mice displayed distinct differences compared to their littermates, characterized by higher abundances of Anaeroplasma, Prevotella, Staphylococcus, Jeotgalicoccus, and Helicobacter, and a lower abundance of Bifidobacterium. Notably, a strong association between Jeotgalicoccus as well as Staphylococcus and serum 5-HT levels was observed in co-occurrence network. Furthermore, mice that received fecal microbiota transplants from TGR5-/- mice displayed anxiety and depression -like behaviors, accompanied by alterations in 5-HT levels in the hippocampus and serum.

LIMITATIONS

Study limitations for gut bacteria were analyzed at the genus level only.

CONCLUSION

TGR5 deletion in mice induces anxiety and depression-like behaviors, linked to reduced 5-HT levels in serum and the hippocampus. Gut microbiota changes play a direct role in these behaviors and serotonin alterations. This implicates TGR5 and gut bacteria in mood regulation, with potential therapeutic implications.

Recent advances in anxiety disorders: Focus on animal models and pathological mechanisms

Anxiety disorders have become one of the most severe psychiatric disorders, and the incidence is increasing every year. They impose an extraordinary personal and socioeconomic burden. Anxiety disorders are influenced by multiple complex and interacting genetic, psychological, social, and environmental factors, which contribute to disruption or imbalance in homeostasis and eventually cause pathologic anxiety. The selection of a suitable animal model is important for the exploration of disease etiology and pathophysiology, and the development of new drugs. Therefore, a more comprehensive understanding of the advantages and limitations of existing animal models of anxiety disorders is helpful to further study the underlying pathological mechanisms of the disease. This review summarizes animal models and the pathogenesis of anxiety disorders, and discusses the current research status to provide insights for further study of anxiety disorders.

The emerging role of the gut microbiome in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) occurs in some people following exposure to a terrifying or catastrophic event involving actual/threatened death, serious injury, or sexual violence. PTSD is a common and debilitating mental disorder that imposes a significant burden on individuals, their families, health services, and society. Moreover, PTSD is a risk factor for chronic diseases such as coronary heart disease, stroke, diabetes, as well as premature mortality. Furthermore, PTSD is associated with dysregulated immune function. Despite the high prevalence of PTSD, the mechanisms underlying its etiology and manifestations remain poorly understood. Compelling evidence indicates that the human gut microbiome, a complex community of microorganisms living in the gastrointestinal tract, plays a crucial role in the development and function of the host nervous system, complex behaviors, and brain circuits. The gut microbiome may contribute to PTSD by influencing inflammation, stress responses, and neurotransmitter signaling, while bidirectional communication between the gut and brain involves mechanisms such as microbial metabolites, immune system activation, and the vagus nerve. In this literature review, we summarize recent findings on the role of the gut microbiome in PTSD in both human and animal studies. We discuss the methodological limitations of existing studies and suggest future research directions to further understand the role of the gut microbiome in PTSD.

Efficacy and safety of Lacticaseibacillus paracasei Lpc-37® in students facing examination stress: A randomized, triple-blind, placebo-controlled clinical trial (the ChillEx study)

Lacticaseibacillus paracasei Lpc-37 (Lpc-37) has previously shown to reduce perceived stress in healthy adults. The ChillEx study investigated whether Lpc-37 reduces stress in a model of chronic examination stress in healthy students. One hundred ninety university students (18-40 y) were randomized to take 1.56 × 1010 colony-forming units of Lpc-37 or placebo (1:1) each day for 10 weeks, in a triple-blind, parallel, multicenter clinical trial consisting of six visits: two screening visits, a baseline visit, and visits at 4, 8, and 10 weeks after baseline. The primary objective was to demonstrate that Lpc-37 reduces stress, as measured by the change in state anxiety from baseline to just before the first examination, after 8 weeks using the State Trait Anxiety Inventory (STAI-state). Secondary objectives aimed to demonstrate that Lpc-37 modulates psychological stress-induced symptoms and biomarkers related to mood and sleep. An exploratory analysis of fecal microbiota composition was also conducted. There was no difference between Lpc-37 and placebo groups in the change of STAI-state score (estimate 1.03; 95% confidence interval [CI]: -1.62, 3.67; p = 0.446). None of the secondary outcomes resulted in significant results when corrected for multiplicity, but exploratory results were notable. Results showed an improvement in sleep-disturbance scores (odds ratio 0.30; 95% CI: 0.11, 0.82; p = 0.020) and reduction in duration of sleep (odds ratio 3.52; 95% CI: 1.46, 8.54; p = 0.005) on the Pittsburgh Sleep Quality Index questionnaire after 8 weeks in the Lpc-37 group compared to placebo. A reduction in Bond Lader VAS-alertness was also demonstrated in the Lpc-37 group compared to placebo (estimate -3.97; 95% CI: -7.78, -0.15; p = 0.042) just prior to the examination. Analysis of fecal microbiota found no differences between study groups for alpha and beta diversity or microbiota abundance. Adverse events were similar between groups. Vital signs, safety-related laboratory measures, and gastrointestinal parameters were stable during the trial. In conclusion, probiotic Lpc-37 was safe but had no effect on stress, mood, or anxiety in healthy university students in this model of chronic academic stress. ClinicalTrials.gov: NCT04125810.

Altered gut microbiota profile in patients with perimenopausal panic disorder

Introduction

Females in the perimenopausal period are susceptible to mood disorders. Perimenopausal panic disorder (PPD) is characterized by repeated and unpredictable panic attacks during perimenopause, and it impacts the patient's physical and mental health and social function. Pharmacotherapy is limited in the clinic, and its pathological mechanism is unclear. Recent studies have demonstrated that gut microbiota is strongly linked to emotion; however, the relation between PPD and microbiota is limitedly known.

Methods

This study aimed to discover specific microbiota in PPD patients and the intrinsic connection between them. Gut microbiota was analyzed in PPD patients (n = 40) and healthy controls (n = 40) by 16S rRNA sequencing.

Results

The results showed reduced α-diversity (richness) in the gut microbiota of PPD patients. β-diversity indicated that PPD and healthy controls had different intestinal microbiota compositions. At the genus level, 30 species of microbiota abundance had significantly different between the PPD and healthy controls. In addition, HAMA, PDSS, and PASS scales were collected in two groups. It was found that Bacteroides and Alistipes were positively correlated with PASS, PDSS, and HAMA.

Discussion

Bacteroides and Alistipes dysbiosis dominate imbalanced microbiota in PPD patients. This microbial alteration may be a potential pathogenesis and physio-pathological feature of PPD. The distinct gut microbiota can be a potential diagnostic marker and a new therapeutic target for PPD.

Bifidobacterium: a probiotic for the prevention and treatment of depression

Depression is a common psychological disease, which has become one of the main factors affecting human health. It has a serious impact on individuals, families, and society. With the prevalence of COVID-19, the incidence of depression has further increased worldwide. It has been confirmed that probiotics play a role in preventing and treating depression. Especially, Bifidobacterium is the most widely used probiotic and has positive effects on the treatment of depression. The mechanisms underlying its antidepressant effects might include anti-inflammation and regulation of tryptophan metabolism, 5-hydroxytryptamine synthesis, and the hypothalamus-pituitary-adrenal axis. In this mini-review, the relationship between Bifidobacterium and depression was summarized. It is hoped that Bifidobacterium-related preparations would play a positive role in the prevention and treatment of depression in the future.

Association between Dairy Consumption and Psychological Symptoms: Evidence from a Cross-Sectional Study of College Students in the Yangtze River Delta Region of China

BACKGROUND

Assessing the dairy consumption and psychological symptoms of Chinese college students as a reference for the mental health of Chinese college students.

METHODS

A three-stage stratified whole-group sampling method was used to investigate dairy consumption and psychological symptoms among 5904 (2554 male students, accounting for 43.3% of the sample) college students in the Yangtze River Delta region. The mean age of the subjects was 20.13 ± 1.24 years. Psychological symptoms were surveyed using the Brief Questionnaire for the Assessment of Adolescent Mental Health. The detection rates of emotional problems, behavioral symptoms, social adaptation difficulties and psychological symptoms among college students with different dairy consumption habits were analyzed using chi-square tests. The association between dairy consumption and psychological symptoms was assessed using a logistic regression model.

RESULTS

College students from the "Yangtze River Delta" region of China participated in the study, of which 1022 (17.31%) had psychological symptoms. The proportions of participants with dairy consumption of ≤2 times/week, 3-5 times/week, and ≥6 times/week were 25.68%, 42.09%, and 32.23%, respectively. Using dairy consumption ≥6 times/week as a reference, multifactor logistic regression analysis showed that college students with dairy consumption ≤2 times/week (OR = 1.42, 95% CI: 1.18, 1.71) were at higher risk of psychological symptoms (p < 0.001).

CONCLUSION

During the COVID-19 pandemic, Chinese college students with lower dairy consumption exhibited higher detection rates of psychological symptoms. Dairy consumption was negatively associated with the occurrence of psychological symptoms. Our study provides a basis for mental health education and increasing knowledge about nutrition among Chinese college students.

The current state of research for psychobiotics use in the management of psychiatric disorders-A systematic literature review

The need to find new therapeutic interventions in patients diagnosed with psychiatric disorders is supported by the data suggesting high rates of relapse, chronic evolution, therapeutic resistance, or lack of adherence and disability. The use of pre-, pro-, or synbiotics as add-ons in the therapeutic management of psychiatric disorders has been explored as a new way to augment the efficacy of psychotropics and to improve the chances for these patients to reach response or remission. This systematic literature review focused on the efficacy and tolerability of psychobiotics in the main categories of psychiatric disorders and it has been conducted through the most important electronic databases and clinical trial registers, using the PRISMA 2020 guidelines. The quality of primary and secondary reports was assessed using the criteria identified by the Academy of Nutrition and Diabetics. Forty-three sources, mostly of moderate and high quality, were reviewed in detail, and data regarding the efficacy and tolerability of psychobiotics was assessed. Studies exploring the effects of psychobiotics in mood disorders, anxiety disorders, schizophrenia spectrum disorders, substance use disorders, eating disorders, attention deficit hyperactivity disorder (ADHD), neurocognitive disorders, and autism spectrum disorders (ASD) were included. The overall tolerability of the interventions assessed was good, but the evidence to support their efficacy in specific psychiatric disorders was mixed. There have been identified data in favor of probiotics for patients with mood disorders, ADHD, and ASD, and also for the association of probiotics and selenium or synbiotics in patients with neurocognitive disorders. In several domains, the research is still in an early phase of development, e.g., in substance use disorders (only three preclinical studies being found) or eating disorders (one review was identified). Although no well-defined clinical recommendation could yet be formulated for a specific product in patients with psychiatric disorders, there is encouraging evidence to support further research, especially if focused on the identification of specific sub-populations that may benefit from this intervention. Several limitations regarding the research in this field should be addressed, i.e., the majority of the finalized trials are of short duration, there is an inherent heterogeneity of the psychiatric disorders, and the diversity of the explored Philae prevents the generalizability of the results from clinical studies.

The Gut-Brain-Microbiome Connection: Can Probiotics Decrease Anxiety and Depression?

Anxiety and depression are highly prevalent mood disorders worldwide. Complete remission of symptoms is often difficult to achieve, despite following recommended treatment guidelines. Numerous antidepressants and anxiolytics exist, and new drugs are being developed constantly, yet the incidence of common mood disorders continues to rise. Despite the prevalence of these issues, mental health treatment has not evolved much in recent years. An exciting area of research uncovered in the past decade is the gut-brain-microbiome axis, a bi-directional communication pathway. Because the human microbiome is closely related to mood, research is being done to investigate whether probiotic supplementation could potentially affect symptoms of anxiety and depression.

Psycho-Microbiology, a New Frontier for Probiotics: An Exploratory Overview

Probiotics are gradually gaining importance in the field of psychiatry in the form of psychobiotics. Psychobiotics' studies examine the existing relationship between gut microbiota and mental phenomena; the intake of certain strains of probiotics, such as Bifidobacterium and Lactobacillus, for example, allow the gut microbial system to be modified in order to provide benefits at the psychic, immune, hormonal, and mental levels. Those who suffer from forms of depression, anxiety disorders, chronic stress, low mood, but also people who do not suffer from such disorders, can therefore benefit from the use of psychobiotics. Thanks to probiotics, neurochemicals can in fact be produced within the gut microbiota and interact with receptors of the enteric nervous system that innervate the entire gastrointestinal tract. Once they enter the portal circulation, these substances go on to influence components of the nervous system and ultimately the brain, through what is called the gut-brain axis. This article proposes an exploratory overview of the proven effects of probiotics on brain activity and psycho-related diseases, focusing on clinical studies and measurable outcomes. The search was conducted using two different online tools: ClinicalTrials.gov and PubMed.

Consumption of fermented dairy products is associated with lower anxiety levels in Azorean university students

A growing number of studies have found that the gut microbiota is involved in a variety of psychological processes and neuropsychiatric disorders, which include mood and anxiety disorders. Consumption of dairy products may contain bioactive compounds and probiotic bacteria with various therapeutic benefits. The aim of the study was to investigate possible associations between the frequency of consumption of different types of dairy products and the state of anxiety in university students. The subjects were 311 Azorean university students, 231 women and 80 men, with an average age of 20.5 years. Subjects completed a quantitative questionnaire on the frequency of dairy product consumption and a short version of the Spielberger State-Trait Anxiety Inventory (STAI) test. Among dairy products, semi-skimmed milk was the most commonly consumed, followed by cheese (ripened), drinking yogurt, skim milk, and set yogurt, while fresh cheese, whole milk, and dairy ice cream were the least common. Discriminant analysis showed that consumption of fermented products (yogurt and cheese) was significantly higher (P < 0.05) in the group with low anxiety level (score <40 in STAI test) than in the group with higher anxiety level (score ≥ 40). In this analysis, 62.4% of the initially grouped cases were correctly classified according to the frequency of fermented products consumption. No correlations were found between anxiety and unfermented dairy products. The results indicate that the consumption of fermented dairy products has a positive effect on reducing anxiety in young Azorean university students.

Probiotics, prebiotics and postbiotics for better sleep quality: a narrative review

There is a growing prevalence of sleep problems and insomnia worldwide, urging the development of new treatments to tackle this increase. Several studies have suggested that the gut microbiome might influence sleep quality. The gut microbiome affects the host's health via the production of metabolites and compounds with neuroactive and immunomodulatory properties, which include short-chain fatty acids, secondary bile acids and neurotransmitters. Several of these metabolites and compounds are independently known as wakefulness-promoting (serotonin, epinephrine, dopamine, orexin, histamine, acetylcholine, cortisol) or sleep-promoting (gamma-aminobutyric acid, melatonin). The primary aim of this review was to evaluate the potential of pro-, pre- and postbiotic treatments to improve sleep quality. Additionally, we aimed to evaluate whether each of the treatments could ameliorate stress and anxiety, which are known to bidirectionally correlate with sleep problems. Lastly, we provided a mechanistic explanation for our findings. A literature search was conducted using PubMed, Scopus, Web of Science, and Google Scholar to compare all human trials that met our inclusion criteria and were published before November 2021. We furthermore discussed relevant findings from animal experiments to provide a mechanistic insight. While several studies found that sleep latency, sleep length, and cortisol levels improved after pro-, pre- or postbiotic treatment, others did not show any significant improvements for sleep quality, stress, or anxiety. These discrepancies can be explained by between-study variations in study designs, study populations, treatments, type and level of distress, and sex differences. We conclude that the trials discussed provide some evidence for prebiotics, postbiotics, and traditional probiotics, such as those belonging to lactobacilli and bifidobacteria, to improve sleep quality and stress, but stronger evidence might be found in the future after implementing the methodological adjustments that are suggested in this review.

Obesity and the Brain

Innate and adaptive immunity are essential for neurodevelopment and central nervous system (CNS) homeostasis; however, the fragile equilibrium between immune and brain cells can be disturbed by any immune dysregulation and cause detrimental effects. Accumulating evidence indicates that, despite the blood-brain barrier (BBB), overactivation of the immune system leads to brain vulnerability that increases the risk of neuropsychiatric disorders, particularly upon subsequent exposure later in life. Disruption of microglial function in later life can be triggered by various environmental and psychological factors, including obesity-driven chronic low-grade inflammation and gut dysbiosis. Increased visceral adiposity has been recognized as an important risk factor for multiple neuropsychiatric conditions. The review aims to present our current understanding of the topic.

Guts Imbalance Imbalances the Brain: A Review of Gut Microbiota Association With Neurological and Psychiatric Disorders

Over the last 10 years, there has been a growing interest in the relationship between gut microbiota, the brain, and neurologic-associated affections. As multiple preclinical and clinical research studies highlight gut microbiota’s potential to modulate the general state of health state, it goes without saying that gut microbiota plays a significant role in neurogenesis, mental and cognitive development, emotions, and behaviors, and in the progression of neuropsychiatric illnesses. Gut microbiota produces important biologic products that, through the gut-brain axis, are directly connected with the appearance and evolution of neurological and psychiatric disorders such as depression, anxiety, bipolar disorder, autism, schizophrenia, Parkinson’s disease, Alzheimer’s disease, dementia, multiple sclerosis, and epilepsy. This study reviews recent research on the link between gut microbiota and the brain, and microbiome’s role in shaping the development of the most common neurological and psychiatric illnesses. Moreover, special attention is paid to the use of probiotic formulations as a potential non-invasive therapeutic opportunity for prevention and management of neuropsychiatric-associated affections.

Anorexia nervosa and gut microbiome: implications for weight change and novel treatments

INTRODUCTION

Host-microbiota interactions may be involved in many physical and psychological functions ranging from the digestion of food, maintenance of immune homeostasis, to the regulation of mood and cognition. Microbiome dysbiosis has been consistently described in many diseases. The pathogenesis and weight regulation mechanism in anorexia nervosa (AN) also seem to be implicated in the dynamic bidirectional adjustment of the microbiota-gut-brain axis. This review aims at elucidating this relationship.

AREA COVERED

This review starts with a description of pathogenic gut-brain pathways. Next, we focus on the latest research on the associations between gut microbiota and weight change in the condition of AN. The strategies to alter the intestinal microbiome for the treatment of this disorder are discussed, including dietary, probiotics, prebiotics, synbiotics, and fecal microbiota transplantation.

EXPERT OPINION

Gut microbiome is inextricably linked to AN. It may regulate weight gain in the process of refeeding via the microbiota-gut-brain axis, while the specific mechanism has yet to be clearly established. In the future, a better understanding of gut microbiome could have implications for developing microbiome-based prevention, diagnostics and therapies.

A Systematic Review of Psychobiotic Interventions in Children and Adolescents to Enhance Cognitive Functioning and Emotional Behavior

This systematic review brings together human psychobiotic interventions in children and adolescents (aged 6-25 years) to evaluate the efficacy of pre- and probiotic supplements on stress, anxiety, and cognitive outcomes. Psychobiotic interventions in animal studies highlighted sensitivity to effects during development and maturation in multiple domains from emotion to cognitive processing. Several translational psychobiotic interventions in humans have been carried out to assess effects on emotion and cognition during childhood and into adulthood. The findings illustrate that there are limited consistent psychobiotic effects in developing human populations, and this is proposed to be due to heterogeneity in the trials conducted. Consequentially, it is recommended that three specific factors are considered in future psychobiotic trials: (1) Specificity of population studied (e.g., patients, developmental age), (2) specificity of intervention, and (3) homogeneity in outcome measures.

Effect of Probiotics on Psychiatric Symptoms and Central Nervous System Functions in Human Health and Disease: A Systematic Review and Meta-Analysis

Background: The gut microbiota impacts on central nervous system (CNS) function via the microbiota–gut–brain axis. Thus, therapeutics targeting the gut microbiota such as probiotics have the potential for improving mental health. This meta-analysis synthesizes the evidence regarding the impacts of probiotics on psychological well-being, psychiatric symptoms and CNS functioning. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were applied for executing this review using the databases PubMed, Web of Science and Cochrane Library. The data were summarized at qualitative and quantitative level. Results: Fifty-four randomized placebo-controlled studies were included, of which 30 were eligible for meta-analysis. If investigated, the probiotics mostly exerted effects on CNS function. Most probiotics did not affect mood, stress, anxiety, depression and psychiatric distress when compared to placebo at the qualitative level. At quantitative level, depression and psychiatric distress improved slightly in the probiotic condition (depression: mean difference −0.37 (95% CI: −0.55, −0.20); p ≤ 0.0001; psychiatric distress: mean difference −0.33 (95% CI: −0.53, −0.13); p = 0.001). Conclusions: To date it is unclear to which extent and in which specific areas next generation probiotics selected and developed for their ability to improve psychiatric condition and potentially other CNS functions are promising.

One Giant Leap from Mouse to Man: The Microbiota-Gut-Brain Axis in Mood Disorders and Translational Challenges Moving towards Human Clinical Trials

The microbiota–gut–brain axis is a bidirectional communication pathway that enables the gut microbiota to communicate with the brain through direct and indirect signaling pathways to influence brain physiology, function, and even behavior. Research has shown that probiotics can improve several aspects of health by changing the environment within the gut, and several lines of evidence now indicate a beneficial effect of probiotics on mental and brain health. Such evidence has prompted the arrival of a new term to the world of biotics research: psychobiotics, defined as any exogenous influence whose effect on mental health is bacterially mediated. Several taxonomic changes in the gut microbiota have been reported in neurodevelopmental disorders, mood disorders such as anxiety and depression, and neurodegenerative disorders such as Alzheimer’s disease. While clinical evidence supporting the role of the gut microbiota in mental and brain health, and indeed demonstrating the beneficial effects of probiotics is rapidly accumulating, most of the evidence to date has emerged from preclinical studies employing different animal models. The purpose of this review is to focus on the role of probiotics and the microbiota–gut–brain axis in relation to mood disorders and to review the current translational challenges from preclinical to clinical research.

Functional roles of the microbiota-gut-brain axis in Alzheimer’s disease: Implications of gut microbiota-targeted therapy

Increasing scientific evidence demonstrates that the gut microbiota influences normal physiological homeostasis and contributes to pathogenesis, ranging from obesity to neurodegenerative diseases, such as Alzheimer’s disease (AD). Gut microbiota can interact with the central nervous system (CNS) through the microbiota-gut-brain axis. The interaction is mediated by microbial secretions, metabolic interventions, and neural stimulation. Here, we review and summarize the regulatory pathways (immune, neural, neuroendocrine, or metabolic systems) in the microbiota-gut-brain axis in AD pathogenesis. Besides, we highlight the significant roles of the intestinal epithelial barrier and blood–brain barrier (BBB) in the microbiota-gut-brain axis. During the progression of AD, there is a gradual shift in the gut microbiota and host co-metabolic relationship, leading to gut dysbiosis, and the imbalance of microbial secretions and metabolites, such as lipopolysaccharides (LPS) and short-chain fatty acids (SCFAs). These products may affect the CNS metabolic state and immune balance through the microbiota-gut-brain axis. Further, we summarize the potential microbiota-gut-brain axis-targeted therapy including carbohydrates, probiotics, dietary measures, and propose new strategies toward the development of anti-AD drugs. Taken together, the data in this review suggest that remodeling the gut microbiota may present a tractable strategy in the management and development of new therapeutics against AD and other neurodegenerative diseases.

[Gut microbiome as a therapeutic target in the treatment of depression and anxiety]

There is a bi-directional connection between the gut microbiome and the brain. Changes in the composition of the microbiome affect emotions, behavior, and the stress response involved in the pathogenesis of depression. Depression and anxiety are often associated with dysbiosis and inflammatory bowel disease. Dysbiosis enhances stress response and low-grade systemic inflammation, and vice versa. This vicious circle may be responsible for the formation of depression. Antidepressants therapy should be accompanied by the elimination of dysbiosis. For these purposes diet, prebiotics, probiotics and faecal microbiota transplantation can be used. The advantages and disadvantages of each method are considered. The manipulation of microbiome composition has been shown to have great therapeutic potential in the treatment of depression and anxiety.

The effects of probiotics administration on the gut microbiome in adolescents with anorexia nervosa-A study protocol for a longitudinal, double-blind, randomized, placebo-controlled trial

Objective

Knowledge on gut–brain interaction might help to develop new therapies for patients with anorexia nervosa (AN), as severe starvation‐induced changes of the microbiome (MI) do not normalise with weight gain. We examine the effects of probiotics supplementation on the gut MI in patients with AN.

Method

This is a study protocol for a two‐centre double‐blind randomized‐controlled trial comparing the clinical efficacy of multistrain probiotic administration in addition to treatment‐as‐usual compared to placebo in 60 patients with AN (13–19 years). Moreover, 60 sex‐ and age‐matched healthy controls are included in order to record development‐related changes. Assessments are conducted at baseline, discharge, 6 and 12 months after baseline. Assessments include measures of body mass index, psychopathology (including eating‐disorder‐related psychopathology, depression and anxiety), neuropsychological measures, serum and stool analyses. We hypothesise that probiotic administration will have positive effects on the gut microbiota and the treatment of AN by improvement of weight gain, gastrointestinal complaints and psychopathology, and reduction of inflammatory processes compared to placebo.

Conclusions

If probiotics could help to normalise the MI composition, reduce inflammation and gastrointestinal discomfort and increase body weight, its administration would be a readily applicable additional component of multi‐modal AN treatment.

Patients with anorexia nervosa face profound alterations of the gut microbiome which does not normalise with weight gain.

Alterations in the gut microbiome in patients with anorexia nervosa are linked to psychopathological symptoms and neurophysiological deficits, for example, related to the reward system.

This is the first study examining the effects of probiotics administration in adolescents with anorexia nervosa using a randomized controlled trial design.

Probiotics for Mental Health: A Review of Recent Clinical Trials

The digestive system is involved in providing both regulatory and biochemical signaling to the nervous system via the gut–brain axis. Major brain neurotransmitters within the enteric nervous system include acetylcholine, serotonin, and norepinephrine, which are triggered by various stimuli within the digestive system, including the microbiota. Associations between the gut microbiome and activation of neuroreceptors and neurotransmitters are related to factors such as appetite control, mood, and memory. This column presents the results of a brief review of recently published clinical trials related to gut microbiome interventions (n = 11) that aimed to address a variety of mental health outcomes. The impacts of probiotics on mental health and other clinical outcomes vary by the health of study participants. Continuing research on the mental health benefits of probiotics in healthy individuals is necessary.

A systematic review of the effects of probiotics on depression and anxiety: an alternative therapy?

This review aims to understand and analyse the effects of probiotics on depression, anxiety and psychological stress. These disorders are among the leading causes of disability worldwide. Conventional pharmacotherapies usually have a poor response or adverse side effects. In this context, recent studies have demonstrated a dense bi-directional communication named gut-brain axis. Evidences are demonstrating the relationship between disturbance in the enteric microbiome and psychiatric disorders, paving the way for the emergence of alternative therapies. A systematic search for randomized double/triple blind placebo-controlled clinical trials was performed in PubMed, Scopus and Lilacs. The studies selection followed the recommendations of the main items for report systematic reviews and meta-analyses (PRISMA). Nine articles met the criteria and were analysed for effects on depression, anxiety, psychological stress and biomarkers. Seven found positive results in at least one of the items. We concluded that the use of probiotics to alleviate depressive symptoms and anxiety is promising, mainly due to its potential anti-inflammatory effect, but additional and more rigorous double blind randomized clinical trials are necessary to endorse such conclusions.

Mining microbe-disease interactions from literature via a transfer learning model

Background

Interactions of microbes and diseases are of great importance for biomedical research. However, large-scale of microbe–disease interactions are hidden in the biomedical literature. The structured databases for microbe–disease interactions are in limited amounts. In this paper, we aim to construct a large-scale database for microbe–disease interactions automatically. We attained this goal via applying text mining methods based on a deep learning model with a moderate curation cost. We also built a user-friendly web interface that allows researchers to navigate and query required information.

Results

Firstly, we manually constructed a golden-standard corpus and a sliver-standard corpus (SSC) for microbe–disease interactions for curation. Moreover, we proposed a text mining framework for microbe–disease interaction extraction based on a pretrained model BERE. We applied named entity recognition tools to detect microbe and disease mentions from the free biomedical texts. After that, we fine-tuned the pretrained model BERE to recognize relations between targeted entities, which was originally built for drug–target interactions or drug–drug interactions. The introduction of SSC for model fine-tuning greatly improved detection performance for microbe–disease interactions, with an average reduction in error of approximately 10%. The MDIDB website offers data browsing, custom searching for specific diseases or microbes, and batch downloading.

Conclusions

Evaluation results demonstrate that our method outperform the baseline model (rule-based PKDE4J) with an average \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$F_1$$\end{document}F1-score of 73.81%. For further validation, we randomly sampled nearly 1000 predicted interactions by our model, and manually checked the correctness of each interaction, which gives a 73% accuracy. The MDIDB webiste is freely avaliable throuth http://dbmdi.com/index/

Probiotics: Potential novel therapeutics for microbiota-gut-brain axis dysfunction across gender and lifespan

Probiotics are live microorganisms, which when administered in adequate amounts, present a health benefit for the host. While the beneficial effects of probiotics on gastrointestinal function are generally well recognized, new animal research and clinical studies have found that alterations in gut microbial communities can have a broad range of effects throughout the body. Non-intestinal sites impacted include the immune, endocrine, cardiovascular and the central nervous system (CNS). In particular, there has been a growing interest and appreciation about the role that gut microbiota may play in affecting CNS-related function through the 'microbiota-gut-brain axis'. Emerging evidence suggests potential therapeutic benefits of probiotics in several CNS conditions, such as anxiety, depression, autism spectrum disorders and Parkinson's disease. There may also be some gender-specific variances in terms of probiotic mediated effects, with the gut microbiota shaping and being concurrently molded by the hormonal environment governing differences between the sexes. Probiotics may influence the ability of the gut microbiome to affect a variety of biological processes in the host, including neurotransmitter activity, vagal neurotransmission, generation of neuroactive metabolites and inflammatory response mediators. Some of these may engage in cross talk with host sex hormones, such as estrogens, which could be of relevance in relation to their effects on stress response and cognitive health. This raises the possibility of gender-specific variation with regards to the biological action of probiotics, including that on the endocrine and central nervous systems. In this review we aim to describe the current understanding in relation to the role and use of probiotics in microbiota-gut-brain axis-related dysfunction. Furthermore, we will address the conceptualization and classification of probiotics in the context of gender and lifespan as well as how restoring gut microbiota composition by clinical or dietary intervention can help in supporting health outcomes other than those related to the gastrointestinal tract. We also evaluate how these new learnings may impact industrial effort in probiotic research and the discovery and development of novel and more personalized, condition-specific, beneficial probiotic therapeutic agents.

Evolution of Intestinal Microbiota of Asphyxiated Neonates Within 1 Week and Its Relationship With Neural Development at 6 Months

Introduction: Asphyxia is an emergent condition in neonates that may influence the function of the nervous system. Research has shown that intestinal microbiota is very important for neurodevelopment. Studies regarding the association between gut microbiota and neurodevelopment outcome in asphyxiated newborns remain scarce. Objective: To study the microbial characteristics of asphyxiated neonates within 1 week of life and to investigate their relationship with neural development at 6 months. Methods: The feces produced on days 1, 3, and 5, and the clinical data of full-term neonates with asphyxia and without asphyxia, delivered from March 2019 to October 2020 at Peking University First Hospital, were collected. We used 16S ribosomal deoxyribonucleic acid amplicon sequencing to detect the intestinal microbiota of asphyxiated neonates and neonates in the control group. We followed up asphyxiated neonates for 6 months and used the Ages and Stages Questionnaires-3 (ASQ-3) to evaluate their development. Results: A total of 45 neonates were enrolled in the study group and 32 were enrolled in the control group. On day 1, the diversity and richness of the microflora of the study group were more than those of the control group. Non-metric multidimensional scaling analysis showed significant differences in the microbiota of the two groups on days 1, 3, and 5. At the phylum level, the main microflora of the two groups were not different. At the genus level, the study group had increased relative abundance of Clostridium_sensu_stricto_1, Lachnoclostridium, Fusicatenibacter, etc. on day 1. On day 3, the relative abundance of Clostridium_sensu_stricto_1, Fusicatenibacter, etc. was still greater than that of the control group, and the relative abundance of Staphylococcus was less than that of the control group. On day 5, the relative abundance of Clostridium_sensu_stricto_1 and Lachnoclostridium was still higher than that of the control group, and the relative abundance of Dubosiella in the study group was significantly increased. At the species level, on day 3, the relative abundance of Staphylococcus caprae in the study group was less than that in the control group. Linear discriminant analysis effect size showed that the microbiota of the study group mainly consisted of Lachnospiraceae and Clostridia on day 1 and Clostridia on day 3. In the control group, Staphylococcus was the dominant bacterium on day 3. Neonates in the study group were followed up for 6 months, and the communication score of ASQ-3 was negatively correlated with the relative abundance of Lachnospiraceae and Clostridia on day 1. Conclusion: The diversity and richness of the microbiota of asphyxiated neonates on the first day of life were significantly increased and mainly consisted of pathogenic flora. Lachnospiraceae and Clostridia found in neonates with asphyxia on day 1 of life may be related to neural development at 6 months.

Drugs and bugs: Negative affect, psychostimulant use and withdrawal, and the microbiome

BACKGROUND AND OBJECTIVES

A growing body of literature demonstrates that the human microbiota plays a crucial role in health and disease states, as well as in the body's response to stress. In addition, the microbiome plays a role in psychological well-being and regulating negative affect. Regulation of negative affect is a factor in psychostimulant abuse disorders. We propose a risk chain in which stress leads to negative affect that places an individual at risk to develop or relapse to psychostimulant abuse disorder. Stress, negative affect, and psychostimulant use all alter the gut microbiome.

METHODS

This review brings together the literature on affective disorders, stress, and psychostimulant abuse disorders to assess possible modulatory actions of the gut-brain axis to regulate these conditions.

RESULTS

Studies reviewed across the various disciplines suggest that the dysbiosis resulting from drug use, drug withdrawal, or stress may cause an individual to be more susceptible to addiction and relapse. Probiotics and prebiotics reduce stress and negative affect.

SCIENTIFIC SIGNIFICANCE

Treatment during the withdrawal phase of psychostimulant abuse disorder, when the microbiome is altered, may ameliorate the symptoms of stress and negative affect leading to a reduced risk of relapse to psychostimulant use.

Probiotics-targeting new milestones from gut health to mental health

Conventional probiotic food research was primarily focused on their benefits for gut health. Recently with the confirmation that the gut microbiota has a bidirectional connection with the brain, it is being proposed that modification of the microbiota can possibly extirpate neurological diseases. Development of probiotic foods and formulations for neural health benefits has garnered interest, with a renewed focus. In this context, this review discusses the evidences collected on the anxiolytic and antidepressant effects of probiotics, especially during the time span of 2015-till now. Although, more clinical trials are necessary to elucidate the exact mechanism of probiotic mode of action but several of the established probiotic strains have been investigated and it appears that few of them have demonstrated their potential as 'psychobiotics'. The formulation of new psychobiotic-based therapeutics is in the spotlight. It is expected that in near future, biological effect of probiotics on neurological conditions will open up an entirely new avenue for personalized medication and healthcare in mental health, and they can be tailored according to the gut-microbiota of specific individuals.

Psychobiotic interventions for anxiety in young people: a systematic review and meta-analysis, with youth consultation

The human gut microbiome influence on brain function and mental health is an emerging area of intensive research. Animal and human research indicates adolescence as a sensitive period when the gut-brain axis is fine-tuned, where dietary interventions to change the microbiome may have long-lasting consequences for mental health. This study reports a systematic review and meta-analysis of microbiota-targeted (psychobiotics) interventions on anxiety in youth, with discussion of a consultation on the acceptability of psychobiotic interventions for mental health management amongst youth with lived experience. Six databases were searched for controlled trials in human samples (age range: 10-24 years) seeking to reduce anxiety. Post intervention outcomes were extracted as standard mean differences (SMDs) and pooled based on a random-effects model. 5416 studies were identified: 14 eligible for systematic review and 10 eligible for meta-analysis (total of 324 experimental and 293 control subjects). The meta-analysis found heterogeneity I² was 12% and the pooled SMD was -0.03 (95% CI: -0.21, 0.14), indicating an absence of effect. One study presented with low bias risk, 5 with high, and 4 with uncertain risk. Accounting for risk, sensitivities analysis revealed a SMD of -0.16 (95% CI: -0.38, 0.07), indicative of minimal efficacy of psychobiotics for anxiety treatment in humans. There is currently limited evidence for use of psychobiotics to treat anxiety in youth. However, future progress will require a multidisciplinary research approach, which gives priority to specifying mechanisms in the human models, providing causal understanding, and addressing the wider context, and would be welcomed by anxious youths.

Understanding the Connection Between the Gut-Brain Axis and Stress/Anxiety Disorders

PURPOSE OF REVIEW

We review the association of the microbiota-gut-brain axis and anxiety disorder or stress.

RECENT FINDING

The microbiota-gut-brain axis mechanism encompasses a bidirectional relationship between the brain and gastrointestinal organs. Dysregulation of the microbiota-gut-brain axis has been actively revealed in the context of various psychiatric diseases such as neurodevelopmental disorders, schizophrenia, anxiety disorders, and depression. We suggest that onset of anxiety disorders may be correlated with activation of a microbiota-gut-brain mechanism involving the immune system, neurotransmitters, and the hormonal system. By applying a microbiota-gut-brain axis mechanism, the possibility of using gastrointestinal system drugs such as probiotics and antibiotics as treatments for anxiety disorders is a possibility. Although modification of the microbiota-gut-brain axis mechanism has yet to be adopted clinically, it is expected that novel strategies employing this mechanism will be developed and deployed as new treatments not only for anxiety disorders, but also other psychiatric diseases.

Effects of Microbiota Imbalance in Anxiety and Eating Disorders: Probiotics as Novel Therapeutic Approaches

Anxiety and eating disorders produce a physiological imbalance that triggers alterations in the abundance and composition of gut microbiota. Moreover, the gut–brain axis can be altered by several factors such as diet, lifestyle, infections, and antibiotic treatment. Diet alterations generate gut dysbiosis, which affects immune system responses, inflammation mechanisms, the intestinal permeability, as well as the production of short chain fatty acids and neurotransmitters by gut microbiota, which are essential to the correct function of neurological processes. Recent studies indicated that patients with generalized anxiety or eating disorders (anorexia nervosa, bulimia nervosa, and binge-eating disorders) show a specific profile of gut microbiota, and this imbalance can be partially restored after a single or multi-strain probiotic supplementation. Following the PRISMA methodology, the current review addresses the main microbial signatures observed in patients with generalized anxiety and/or eating disorders as well as the importance of probiotics as a preventive or a therapeutic tool in these pathologies.

Roles of Gut Microbiota in the Regulation of Hippocampal Plasticity, Inflammation, and Hippocampus-Dependent Behaviors

The study of the gut microbiota-brain axis has become an intriguing field, attracting attention from both gastroenterologists and neurobiologists. The hippocampus is the center of learning and memory, and plays a pivotal role in neurodegenerative diseases, such as Alzheimer’s disease (AD). Previous studies using diet administration, antibiotics, probiotics, prebiotics, germ-free mice, and fecal analysis of normal and specific pathogen-free animals have shown that the structure and function of the hippocampus are affected by the gut microbiota. Furthermore, hippocampal pathologies in AD are positively correlated with changes in specific microbiota. Genomic and neurochemical analyses revealed significant alterations in genes and amino acids in the hippocampus of AD subjects following a remarkable shift in the gut microbiota. In a recent study, when young animals were transplanted with fecal microbiota derived from AD patients, the recipients showed significant impairment of cognitive behaviors, AD pathologies, and changes in neuronal plasticity and cytokines. Other studies have demonstrated the side effects of antibiotic administration along with the beneficial effects of probiotics, prebiotics, and specific diets on the composition of the gut microbiota and hippocampal functions, but these have been mostly preliminary with unclear mechanisms. Since some specific gut bacteria are positively or negatively correlated to the structure and function of the hippocampus, it is expected that specific gut bacteria administration and other microbiota-based interventions could be potentially applied to prevent or treat hippocampus-based memory impairment and neuropsychiatric disorders such as AD.

Bifidobacterium animalis subsp. lactis BB-12 Improves the State Anxiety and Sports Performance of Young Divers Under Stress Situations: A Single-Arm, Prospective Proof-of-Concept Study

Background

Athletes will increase their state anxiety under stress situations, which will lead to the decline of sports performance. The improvement of anxiety by probiotics has been reported, but there is a lack of research in the athlete population. The purpose of the current study is to explore the effectiveness of probiotics in improving athletes' state anxiety and sports performance under stress situations.

Methods

We conducted this single-arm study in Chongqing Institute of Sports Technology. In the 8-week study, 21 Chongqing young divers (mean age: 9.10 ± 1.80) were given probiotic Bifidobacterium animalis subsp. lactis BB-12 (1 × 10⁹ colony-forming units/100 g) daily. The state anxiety and sports performance of athletes were measured before, during, and after the intervention, and the gut microbiota of athletes was measured before and after the intervention.

Results

The intervention results showed that cognitive state anxiety, somatic state anxiety, and anxiety emotion were improved (cognitive: Z = -3.964, P < 0.001; somatic: Z = -3.079, P = 0.003; anxiety: Z = -2.973, P < 0.001). In terms of gut microbiota, the intervention did not change the gut microbial composition (such as α diversity and β diversity) but increased the abundance of Bifidobacteriaceae. At the 8th week, the performance of athletes under stress was significantly improved (χ² = 7.88, P = 0.019).

Limitations

First of all, due to the restriction of the number of subjects in this study, there was no control group. Secondly, although the athletes' diet was recorded in this study, the influence of this factor on gut microbiota was not eliminated. Finally, the anxiety level of the athletes in this study was obtained through a self-report, lacking physiological data in state anxiety.

Conclusion

The results show that probiotics intervention can improve the state anxiety of athletes under stress situation and improve the performance of athletes under stress situation.

Craft Beers Fermented by Potential Probiotic Yeast or Lacticaseibacilli Strains Promote Antidepressant-Like Behavior in Swiss Webster Mice

This study aimed to produce a probiotic-containing functional wheat beer (PWB) by an axenic culture system with potential probiotic Saccharomyces cerevisiae var boulardii 17 and probiotic-containing functional sour beer (PSB) by a semi-separated co-cultivation system with potential probiotic Lacticaseibacillus paracasei DTA 81 and Saccharomyces cerevisiae S-04. Additionally, results obtained from in vivo behavioral tests with Swiss Webster mice treated with PWB or PSB were provided, which is scarce in the current literature. Although the use of S. boulardii to produce beers is not a novelty, this study demonstrated that S. boulardii 17 performance on sugar wort stills not completely elucidated; therefore, further studies should be considered before using the strain in industrial-scale production. Co-culture systems with lacticaseibacilli strain and S. cerevisiae have been reported in the literature for PSB production. However, lacticaseibacilli survivability in beer can be improved by semi-separated co-cultivation systems, highlighting the importance of growing lacticaseibacilli in the wort before yeast pitching. Besides, kettle hopping must be chosen as the method for hop addition to produce PSB. The dry-hopping method may prevent iso-alpha formation in the wort; however, a tendency to sediment can drag cells at the tank bottom and negatively affect L. paracasei DTA 81 viability. Despite stress factors from the matrices and the stressful conditions encountered during GI transit, potential probiotic S. boulardii 17 and potential probiotic L. paracasei DTA 81 withstood at sufficient doses to promote antidepressant effects in the mice group treated with PWB or PSB, respectively.