The Microbiota-Gut-Brain Axis: Psychoneuroimmunological Insights

Harnessing Probiotics: Exploring the Role of the Gut Microbiome in Combating Obesity

Obesity has become a global health crisis driven by genetic, environmental, and lifestyle factors, often linked to gut microbiome imbalances. Probiotics, particularly Lactobacillus and Bifidobacterium strains, have shown promise in clinical trials by promoting weight loss, improving lipid profiles, and addressing gut dysbiosis associated with obesity. This review surveys the literature on the microbiome and obesity, emphasizing the clinical relevance of probiotics in treatment strategies. Our comprehensive PubMed search highlights the mechanisms through which probiotics influence metabolic health, including their effects on inflammation and appetite regulation. We also explore promising future research directions and the potential for integrating probiotics into clinical practice. While results are encouraging, the evidence is limited by strain variability, small sample sizes, short trial durations, and individual differences in microbiota composition. More extensive, long-term studies with standardized methods are crucial to confirm the effectiveness of probiotics as viable anti-obesity treatments.

Supplementary approaches to perinatal depression: a review of pathogenesis, herbal interventions, and dietary supplements

Although perinatal depression (PND) has garnered increasing attention, few specific pharmacological treatments exist, particularly for breastfeeding mothers concerned about antidepressant safety. The misconception that "natural is harmless" merits caution; herbal remedies and dietary supplements should be regarded as supplementary interventions pending robust safety evidence. This review summarizes recent advances in PND pathogenesis (neurotransmitter dysregulation, inflammation, hormonal imbalance, and microbiota alterations) and emerging drug development strategies, alongside clinical evidence for herbal and dietary supplements. Randomized controlled trial (RCT) findings reveal that while interventions like saffron and vitamin D show promise, significant limitations persist, including inconsistent efficacy, limited long-term safety data, and potential interactions with perinatal physiology. Caution is warranted until comprehensive studies validate the safety and reliability of natural interventions. This review underscores the need for rigorous trials to identify safe, effective PND treatments, particularly for vulnerable populations.

Innovations in the diagnosis, treatment, and management of disorders of gut-brain interaction (DGBI)

INTRODUCTION

Functional dyspepsia (FD) and irritable bowel syndrome (IBS) are the most prevalent disorders of gut-brain interaction (DGBI), frequently overlapping and associated with complex pathophysiological mechanisms. Increasing evidence implicates gut microbiota alterations in driving symptoms via immune activation, altered motility, gut vascular barrier and gut-brain axis disruption.

AREAS COVERED

This review explores the role of gut microbiota in FD and IBS pathogenesis and symptomatology. A comprehensive literature search was conducted using PubMed, EMBASE, and Google Scholar databases, including studies published between January 2013 and March 2025. Particular focus is given to microbiota-targeted therapies such as prebiotics, probiotics, synbiotics, postbiotics, and fecal microbiota transplantation (FMT). The review also discusses multidimensional treatment strategies combining dietary and lifestyle modification, cognitive-behavioral therapy, and pharmacological neuromodulation. Recent advances in diagnostic methods, including capsule-based microbiota sampling and digital tools for remote psychogastroenterology care, are highlighted.

EXPERT OPINION

Despite scientific progress, current DGBI management remains insufficiently personalized. Future approaches should integrate individualized microbiota profiling with targeted interventions and utilize innovative diagnostic and digital health technologies to enhance clinical outcomes in FD and IBS.

Gut Microbiota: A New Challenge in Mood Disorder Research

The gut microbiome has emerged as a novel and intriguing focus in mood disorder research. Emerging evidence demonstrates the significant role of the gut microbiome in influencing mental health, suggesting a bidirectional communication between the gut and the brain. This review examines the latest findings on the gut-microbiota-brain axis and elucidates how alterations in gut microbiota composition can influence this axis, leading to changes in brain function and behavior. Although dietary interventions, prebiotics, probiotics, and fecal microbiota transplantation have yielded encouraging results, significant advances are needed to establish next-generation approaches that precisely target the neurobiological mechanisms of mood disorders. Future research must focus on developing personalized treatments, facilitated by innovative therapies and technological progress, which account for individual variables such as age, sex, drug history, and lifestyle. Highlighting the potential therapeutic implications of targeting the gut microbiota, this review emphasizes the importance of integrating microbiota research into psychiatric studies to develop more effective and personalized treatment strategies for mood disorders.

Association of optic neuritis with incident depressive disorder risk in a Korean nationwide cohort

Studies have highlighted complex bidirectional relationships between autoimmune diseases and depressive disorders. Given that early mental health interventions have substantial public health implications, this study investigated association between optic neuritis, an autoimmune inflammatory disorder of the optic nerve, and risk of developing depressive disorders. Utilizing extensive national health insurance data encompassing almost the entire Korean population, this cohort study included 11,745 patients with optic neuritis and 58,725 age- and sex- matched controls between 2010 and 2017. The diagnosis of optic neuritis was confirmed using ICD-10 code H46 and patient medical records. The association with depression risk identified by ICD-10 codes F32 and F33 was assessed using Cox proportional hazards regression models after adjusting for demographics, lifestyle variables, and other comorbidities. Newly diagnosed optic neuritis was associated with an increased risk of depression (hazard ratio = 1.349, 95% confidence interval: 1.277-1.426), independent of potential confounding factors. Subgroup analysis revealed a stronger association for individuals under 50 years, males, current smokers, and those without hypertension. This association suggests that autoimmune neuroinflammatory responses impact mental health differently across demographics. These findings underscore the importance of implementing routine depression screening and developing targeted early intervention strategies for patients with optic neuritis, particularly for those with a high-risk of depression.

The brain-gut microbiota network (BGMN) is correlated with symptom severity and neurocognition in patients with schizophrenia

The association between the human brain and gut microbiota, known as the "brain-gut-microbiota axis", is involved in the neuropathological mechanisms of schizophrenia (SZ); however, its association patterns and correlations with symptom severity and neurocognition are still largely unknown. In this study, 43 SZ patients and 55 normal controls (NCs) were included, and resting-state functional magnetic resonance imaging (rs-fMRI) and gut microbiota data were acquired for each participant. First, the brain features of brain images and functional brain networks were computed from rs-fMRI data; the gut features of gut microbiota abundance and the gut microbiota network were computed from gut microbiota data. Second, we propose a novel methodology to construct an individual brain-gut microbiota network (BGMN) for each participant by combining the brain and gut features via multiple strategies. Third, discriminative models between SZ patients and NCs were built using the connectivity matrices of the BGMN as input features. Moreover, the correlations between the most discriminative features and the scores of symptom severity and neurocognition were analyzed in SZ patients. The results showed that the best discriminative model between SZ patients and NCs was achieved using the connectivity matrices of the BGMN when all the brain and gut features were integrated, with an accuracy of 0.90 and an area under the curve value of 0.97. The most discriminative features were related primarily to the genera Faecalibacterium and Collinsella, in which the genus Faecalibacterium was linked to the visual system and subcortical cortices and the genus Collinsella was linked to the default network and subcortical cortices. Furthermore, parts of the most discriminative features were significantly correlated with the scores of neurocognition in the SZ patients. The methodology for constructing individual BGMNs proposed in this study can help us reveal the associations between the brain and gut microbiota and understand the neuropathology of SZ.

Therapeutic role of gut microbiota in lung injury-related cognitive impairment

Lung injury can lead to specific neurocognitive dysfunction, and the "triple-hit" phenomenon may be the key theoretical mechanism for the progressive impairment of lung injury-related cognitive impairment. The lung and brain can communicate biologically through immune regulation pathway, hypoxic pathway, neural circuit, mitochondrial dysfunction, and microbial influence, which is called the "lung-brain axis." The gut microbiota is a highly complex community of microorganisms that reside in the gut and communicate with the lung via the "gut-lung axis." The dysregulation of gut microbiota may lead to the migration of pathogenic bacteria to the lung, and directly or indirectly regulate the lung immune response through their metabolites, which may cause or aggravate lung injury. The gut microbiota and the brain interact through the "gut-brain axis." The gut microbiota can influence and regulate cognitive function and behavior of the brain through neural pathway mechanisms, immune regulation pathway and hypothalamic-pituitary-adrenal (HPA) axis regulation. Based on the gut microbiota regulation mechanism of the "gut-lung axis" and "gut-brain axis," combined with the mechanisms of cognitive impairment caused by lung injury, we proposed the "triple-hit" hypothesis. It states that the pathophysiological changes of lung injury trigger a series of events such as immune disorder, inflammatory responses, and microbiota changes, which activate the "lung-gut axis," thus forming a "triple-hit" that leads to the development or deterioration of cognitive impairment. This hypothesis provides a more comprehensive framework for studying and understanding brain dysfunction in the context of lung injury. This review proposes the existence of an interactive tandem network for information exchange among the gut, lung, and brain, referred to as the "gut-lung-brain axis." It further explores the potential mechanism of lung injury-related cognitive impairment caused by multiple interactions of gut microbiota in the "gut-lung-brain axis." We found that there are many numerous pathophysiological factors that influence the interaction within the "gut-lung-brain axis." The impact of gut microbiota on cognitive functions related to lung injury may be mediated through mechanisms such as the "triple-hit" hypothesis, direct translocation of microbes and their metabolites, hypoxic pathway, immune modulation, vagal nerve activity, and the HPA axis regulation, among others. As the research deepens, based on the "triple-hit" hypothesis of lung injury, it is further discovered that gut microbial therapy can significantly change the pathogenesis of the inflammatory process on the "gut-lung-brain axis." It can also relieve lung injury and therapeutically modulate brain function and behavior. This perspective provides a new idea for the follow-up treatment of lung injury-related cognitive impairment caused by dysregulation of gut microbiota.

Irritable Bowel Syndrome: A Hallmark of Psychological Distress in Women?

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by abdominal pain, bloating, and altered bowel habits. Women are disproportionately affected by IBS due to a complex interplay between genetic, environmental, and psychosocial factors, along with a crucial role of the gut-brain axis in modulating both bowel function and pain perception. Evidence suggests a strong association between psychological distress and IBS symptoms. Women with IBS report higher levels of psychological distress compared to men, and sex is a biological variable that shapes several aspects of the mechanisms, epidemiology, and clinical manifestations of IBS. This paper explores the bidirectional relationship between psychological factors and IBS with a focus on women. Stress, anxiety, depression, and childhood trauma contribute to IBS symptomatology, and societal and biological factors unique to women may exacerbate this condition. Strategies for integrated care approaches and gender-specific treatment strategies to improve patient outcomes and quality of life are needed.

Aesthetic Gynecology and Mental Health: What Does It Really Mean for Women?

Body image, a complex interplay of perceptions, thoughts, and feelings about one’s physical appearance, has been a subject of extensive research. It is a dynamic construct that evolves throughout a woman’s lifespan, influenced by a multitude of biological, psychological, and sociocultural factors. From adolescence, marked by the onset of puberty and societal pressures to conform to specific beauty standards, to adulthood and the physical changes associated with aging, women’s body image undergoes significant transformations. Aging is a universal process that affects all organs, including the female genitalia. The vaginal tract undergoes significant atrophy due to declining estrogen levels, particularly during and after menopause. Aesthetic gynecology offers a range of procedures to address both functional and aesthetic concerns related to aging genitalia. Aesthetic gynecology, a burgeoning field within women’s health, provides various procedures aimed at enhancing genital appearance and function. It also helps balance the hormonal and anatomical changes that every woman experiences over time. The goal is to strengthen each patient’s intimate well-being and self-esteem, enabling them to experience intimacy peacefully. While often driven by concerns about physical attractiveness and sexual satisfaction, the psychological implications of these procedures are complex and multifaceted. It is crucial to recognize the interplay between psychological factors and the decision to undergo these procedures. Collaboration between surgeons and mental health professionals can ensure that candidates are psychologically prepared and have realistic expectations. By adopting a patient-centered approach and conducting rigorous research, healthcare providers can ensure that aesthetic gynecology is used as a tool for empowerment rather than exploitation. This article explores the intricate relationship between psychological well-being and aesthetic gynecology, examining how these procedures can impact body image, self-esteem, and overall quality of life.

Eight weeks of resistance exercise improves mood state and intestinal permeability in healthy adults: A randomized controlled trial

To explore a potential link between resistance exercise and the gut-brain axis, this study examined the impact of resistance exercise on intestinal permeability, as indicated by lipopolysaccharide binding protein (LBP), and mood state in healthy adults. Sedentary participants (n = 20; 39.5 ± 12.1 y; 27.4 ± 5.3 kg/m2) were randomly assigned to the resistance exercise (REX) or wait-listed control (CON) groups. REX participants strength trained 3× weekly (advancing from 45%-55% to 70%-80% 1RM for 3-4 sets over 8 weeks). Strength testing, evaluation of mood states, and collection of fasting blood occurred at baseline and weeks 4 and 8. At baseline, LBP concentrations were inversely correlated to all strength measures (r range: -0.48 to -0.57; p < 0.05). The gain in total strength [(split squat left + right)/2 + bench press] was 45% higher for REX versus CON participants (p = 0.019), and serum LBP concentrations fell 16% for REX participants and rose 9% in CON participants (p = 0.014). Mood was significantly improved by resistance training versus control (but this improvement was not related to changes in LBP; r = -0.001). These findings support a role for resistance exercise in improving mood state and intestinal barrier function, but more research is warranted to further explore the effects of resistance training on the gut-brain axis.

Anxiety disorders and the gut microbiota: a bibliometric and visual analysis

Introduction

Anxiety disorder is a common mental illness, yet its specific mechanisms remain unclear. Recent research has revealed a connection between gut microbiota and anxiety disorders. This study aims to assess the current global research landscape, highlight current topics of interest, and explore future research directions in the field of anxiety disorders and gut microbiota.

Methods

We extracted research review articles related to anxiety and gut microbiota from the Web of Science, covering the period from 2004 to 2023. We used VOSviewer 1.6.18.0, Scimago Graphica, and CiteSpace 6.2. R2 to visualize the contributions of countries, institutions, journals, authors, citations, and keywords in this field.

Result

A total of 1198 articles were included in this bibliometric analysis. Over the past two decades, both publications and citations have shown a steady increase. China, the United States, and Canada were the top three countries in terms of publication output. John Cryan from University College Cork had the highest number of publications and citation impact in this area of research. The journal Nutrients had the highest number of publications, while Brain Behavior and Immunity had the most citations. Key research themes in recent years have included anxiety, gut microbiota, depression, stress, gut-brain axis, and probiotics, all of which are likely to be important future research directions.

Conclusion

This analysis has key research areas and emerging trends, including risk factors, stressors, inflammatory responses, the gut-brain axis, and probiotics. These insights can guide researchers towards a more comprehensive understanding of recent advancements in this field, help shape future research directions and facilitate the identification of new therapeutic targets for anxiety disorder, ultimately improving clinical outcomes.

Gut Microbiota-Based Interventions for Parkinson's Disease: Neuroprotective Mechanisms and Current Perspective

Recent evidence links gut microbiota alterations to neurodegenerative disorders, including Parkinson's disease (PD). Replenishing the abnormal composition of gut microbiota through gut microbiota-based interventions "prebiotics, probiotics, synbiotics, postbiotics, and fecal microbiota transplantation (FMT)" has shown beneficial effects in PD. These interventions increase gut metabolites like short-chain fatty acids (SCFAs) and glucagon-like peptide-1 (GLP-1), which may protect dopaminergic neurons via the gut-brain axis. Neuroprotective effects of these interventions are mediated by several mechanisms, including the enhancement of neurotrophin and activation of the PI3K/AKT/mTOR signaling pathway, GLP-1-mediated gut-brain axis signaling, Nrf2/ARE pathway, and autophagy. Other pathways, such as free fatty acid receptor activation, synaptic plasticity improvement, and blood-brain and gut barrier integrity maintenance, also contribute to neuroprotection. Furthermore, the inhibition of the TLR4/NF-кB pathway, MAPK pathway, GSK-3β signaling pathway, miR-155-5p-mediated neuroinflammation, and ferroptosis could account for their protective effects. Clinical studies involving gut microbiota-based interventions have shown therapeutic benefits in PD patients, particularly in improving gastrointestinal dysfunction and some neurological symptoms. However, the effectiveness in alleviating motor symptoms remains mild. Large-scale clinical trials are still needed to confirm these findings. This review emphasizes the neuroprotective mechanisms of gut microbiota-based interventions in PD as supported by both preclinical and clinical studies.

Microbiota and social behavior alterations in a mouse model of down syndrome: Modulation by a synbiotic treatment

Sex differences in the composition and functionality of gut microbiota are an emerging field of interest in neurodevelopmental disorders, as they may help in understanding the phenotypic disparities between males and females. This study aimed to characterize sex-related specific alterations in gut microbiota composition in a mouse model of Down syndrome (Ts65Dn mice, TS mice) through the sequencing of the PCR-amplified 16S ribosomal DNA fraction. Moreover, it intended to examine whether the modulation of gut microbiota by the administration of a synbiotic (SYN) treatment would be beneficial for the behavioral alterations observed in male and female TS mice. Our results show that male, but not female, TS mice exhibit alterations in beta diversity compared to their wild-type (WT) littermates. Sex-dependent differences are also observed in the relative abundance of the classes Bacilli and Clostridia. Administering the SYN effectively counteracts hypersociability in females, and normalizes the overall abundance of Bacilli, specifically by increasing Lactobacillaceae. On the contrary, it rescues emotional recognition deficits in male TS mice and increases the relative abundance of the families Lactobacillaceae, Streptococcaceae and Atopobiaceae. In addition, a metagenome KEGG analysis of differentially enriched pathways shows relevant changes in the cofactor biosynthesis and the amino acid synthesis categories. Finally, following SYN treatment, both male and female TS mice exhibit a robust increase in propionic acid levels compared to WT littermates. These findings suggest sex-specific mechanisms that could link gut microbiota composition with behavior in TS mice, and underscore the potential of targeted gut microbiota interventions to modulate social abnormalities in neurodevelopmental disorders.

The Microbiota-Gut-Brain Axis: Key Mechanisms Driving Glymphopathy and Cerebral Small Vessel Disease

The human microbiota constitute a very complex ecosystem of microorganisms inhabiting both the inside and outside of our bodies, in which health maintenance and disease modification are the main regulatory features. The recent explosion of microbiome research has begun to detail its important role in neurological health, particularly concerning cerebral small vessel disease (CSVD), a disorder associated with cognitive decline and vascular dementia. This narrative review represents state-of-the-art knowledge of the intimate, complex interplay between microbiota and brain health through the gut-brain axis (GBA) and the emerging role of glymphatic system dysfunction (glymphopathy) and circulating cell-derived microparticles (MPs) as mediators of these interactions. We discuss how microbial dysbiosis promotes neuroinflammation, vascular dysfunction, and impaired waste clearance in the brain, which are critical factors in the pathogenesis of CSVD. Further, we discuss lifestyle factors that shape the composition and functionality of the microbiota, focusing on sleep as a modifiable risk factor in neurological disorders. This narrative review presents recent microbiome research from a neuroscientific and vascular perspective to establish future therapeutic avenues in targeting the microbiota to improve brain health and reduce the burden of CSVD.

Altered Function and Structure of the Cerebellum Associated with Gut-Brain Regulation in Crohn's Disease: a Structural and Functional MRI Study

This study employed structural and functional magnetic resonance imaging (MRI) to investigate changes in the function and structure of the cerebellum associated with gut-brain axis (GBA) regulation in patients diagnosed with Crohn's disease (CD). The study comprised 20 CD patients, including 12 with active disease (CD-A) and 8 in remission (CD-R), as well as 21 healthy controls. Voxel-based morphometry (VBM) was utilized for structural analysis of cerebellar gray matter volume, while independent component analysis (ICA) was applied for functional analysis of cerebellar functional connectivity (FC). The results showed significant GMV reduction in the left posterior cerebellar lobe across all CD patients compared to HCs, with more pronounced differences in the CD-A subgroup. Additionally, an increase in mean FC of the cerebellar network was observed in all CD patients, particularly in the CD-A subgroup, which demonstrated elevated FC in the vermis and bilateral posterior cerebellum. Correlation analysis revealed a positive relationship between cerebellar FC and the Crohn's Disease Activity Index (CDAI) and a trend toward a negative association with the reciprocal of the Self-rating Depression Scale (SDS) score in CD patients. The study's findings suggest that the cerebellum may play a role in the abnormal regulation of the GBA in CD patients, contributing to a better understanding of the neural mechanisms underlying CD and highlighting the cerebellum's potential role in modulating gut-brain interactions.

Exploring the Potential of Probiotics and Prebiotics in Major Depression: From Molecular Function to Clinical Therapy

Major depressive disorder (MDD) represents a complex and challenging mental health condition with multifaceted etiology. Recent research exploring the gut-brain axis has shed light on the potential influence of gut microbiota on mental health, offering novel avenues for therapeutic intervention. This paper reviews current evidence on the role of prebiotics and probiotics in the context of MDD treatment. Clinical studies assessing the effects of prebiotic and probiotic interventions have demonstrated promising results, showcasing improvements in depression symptoms and metabolic parameters in certain populations. Notably, prebiotics and probiotics have shown the capacity to modulate inflammatory markers, cortisol levels, and neurotransmitter pathways linked to MDD. However, existing research presents varied outcomes, underscoring the need for further investigation into specific microbial strains, dosage optimization, and long-term effects. Future research should aim at refining personalized interventions, elucidating mechanisms of action, and establishing standardized protocols to integrate these interventions into clinical practice. While prebiotics and probiotics offer potential adjunctive therapies for MDD, continued interdisciplinary efforts are vital to harnessing their full therapeutic potential and reshaping the landscape of depression treatment paradigms.

Network Analysis of Pathogenesis Markers in Murine Chagas Disease Under Antimicrobial Treatment

Chagas disease (CD), a disease affecting millions globally, remains shrouded in scientific uncertainty, particularly regarding the role of the intestinal microbiota in disease progression. This study investigates the effects of antibiotic-induced microbiota depletion on parasite burden, immune responses, and clinical outcomes in BALB/c mice infected with either the Trypanosoma cruzi Colombiana or CL Brener strains. Mice were treated with a broad-spectrum antibiotic cocktail before infection, and parasite burden was quantified via qPCR at 30 and 100 days post-infection (dpi). Immune responses were analyzed using flow cytometry and ELISA, while histopathology was conducted on cardiac and intestinal tissues. Antibiotic treatment uncovered strain-specific correlations, with Colombiana infections affecting Bifidobacterium populations and CL Brener infections linked to Lactobacillus. Microbiota depletion initially reduced parasite burden in the heart and intestine, but an increase was observed in the chronic phase, except in the CL Brener-infected gut, where an early burden spike was followed by a decline. Antibiotic-induced bacterial shifts, such as reductions in Bacteroides and Bifidobacterium, promoted a more pro-inflammatory immune profile. These findings highlight the importance of microbiota and strain-specific factors in CD and suggest further research into microbiota manipulation as a potential therapeutic strategy.

Association between dietary fiber intake and suicidal ideation: a cross-sectional survey

Background

Dietary fiber is beneficial for improving mental health. However, few studies have evaluated the relationship between fiber-rich food and suicidal ideation. Thus, we aimed to assess whether dietary fiber consumption was associated with the risk of suicidal ideation.

Methods

Data of 21,865 American adults were retrieved from the National Health and Nutrition Examination Survey (NHANES). Logistic and restricted cubic spline regression analyses were performed in order to evaluate the association of dietary fiber intake with suicidal ideation, as indicated by item nine of the nine-item Patient Health Questionnaire (PHQ-9). These analyses took into consideration several confounding factors that may potentially influence the results.

Results

Herein, we detected an L-shaped association between dietary fiber intake and the risk of suicidal ideation. For the most conclusive model, an increase of 1 g/1000 kcal/d in dietary fiber intake was accompanied by a 5% reduction in the risk of suicidal ideation. The inflection point of the L-shaped association was located at 7.8 g/1000 kcal/d. When dietary fiber intake exceeded the above level, the risk of suicidal ideation no longer decreased.

Conclusion

Our findings of reduced risk of suicidal ideation in people with higher dietary fiber intake suggest the potential clinical and public health value of dietary fiber. Interventional investigations are warranted to prove whether adhering to a high-fiber diet prevents and reduces suicidality.

Lacticaseibacillus rhamnosus KY16 Improves Depression by Promoting Intestinal Secretion of 5-HTP and Altering the Gut Microbiota

Increasing research suggests a connection between gut microbiota and depressive disorders. Targeted changes to the intestinal flora may contribute to alleviating anxiety and depression. This study aimed to identify probiotics that could attenuate stress-induced abnormal behavior and explore potential mechanisms. The administration of LR.KY16 significantly reduced stress-induced abnormal behaviors and physiological dysfunction. The mechanism may be via regulating the structure of the intestinal microbiota in mice, increasing the abundance of Akkermansia muciniphila, prompting enterochromaffin cells to secrete 5-HTP in the gut, which enters the brain through the bloodstream and promotes the synthesis of 5-HT in the brain, and then activates brain-derived neurotrophic factor (BDNF)/tyrosine kinase receptor B (TrkB) through the 5-HT1A receptor. In addition, LR.KY16 also increased the expression of claudin-7, occludin, and zonula occludens-1 (ZO-1) in the colon, inhibited microglial M1 polarization, and inhibited systemic inflammation.

Risk factors and consequences of mental health problems in nurses: A scoping review of cohort studies

Mental health problems in nurses are prevalent and impairing. To date, no literature has comprehensively synthesised cohort evidence on mental health among nurses. This scoping review aimed to synthesise the existing literature on the risk factors and consequences of mental health problems in nurses. A systematic search was conducted on PubMed, EMBASE, Epistemonikos database, Web of Science, CINAHL, and PsycINFO from inception to March 2023. We identified 171 cohort studies from 16 countries, mostly (95.3%) from high-income economies. This review indicated that nurses worldwide encountered significant mental health challenges, including depression, cognitive impairment, anxiety, trauma/post-traumatic stress disorder, burnout, sleep disorder, and other negative mental health problems. These problems were closely related to various modifiable risk factors such as nurses' behaviours and lifestyles, social support, workplace bullying and violence, shift work, job demands, and job resources. Moreover, nurses' mental health problems have negative effects on their physical health, behaviour and lifestyle, occupation and organisation, and intrapersonal factors. These findings provided an enhanced understanding of mental health complexities among nurses, and shed light on policy enactment to alleviate the negative impact of mental health problems on nurses. Addressing mental health among nurses should be a top priority.

Amnestic syndrome in the course of seronegative limbic encephalitis complicated by drug-resistant epilepsy: a case report

We present the case of a 35-year-old female patient admitted to the hospital with symptoms of rapidly increasing disturbances of consciousness and fever for 48 hours. A lumbar puncture, bacteriological and virological examinations, and initial imaging studies did not show abnormalities. Brain magnetic resonance imaging (MRI), repeated several times, showed hyperintense confluent lesions in both temporal lobes and atrophy of both hippocampi. General examination, cerebrospinal fluid culture, the panel of antineuronal antibodies, and tumor markers remained negative on subsequent repeats. Despite several laboratory and imaging studies, the etiology of the disease could not be established, infections were excluded, and no autoantibodies were found. A diagnosis of probable limbic encephalitis, amnestic syndrome resulting from organic brain damage, and drug-resistant epilepsy was made. The patient, with limbic encephalitis complicated by drug-resistant status epilepticus, was treated with cycles of immunoglobulin and subsequent plasmapheresis. She was then transferred to the Department of Psychiatry for diagnosis and treatment of intermittent psychotic disorders. During hospitalization, the patient was observed to have multiple epileptic seizures with temporal and frontal morphology, amnestic syndrome with confabulations, and periodic psychotic disorders with the occurrence of visual hallucinations. Antiepileptic treatment was escalated by including cenobamate in increasing doses. To control the mental disorders, duloxetine, tiapride, and cognitive function exercises were introduced. There was a slight improvement in memory, a cessation of confabulations, and an emergence of the patient's criticism of the symptoms presented. The psychotic symptoms subsided, and the number of epileptic seizures decreased. The described case portrays a unique co-occurrence of disease symptoms that are difficult to treat. It shows the therapeutic difficulties that can occur in patients with suspected autoimmune encephalitis. Furthermore, it shows the need for multispecialty care of a patient with psychotic symptoms in the course of epilepsy accompanied by amnestic syndrome.

Relationship between human oral microbiome dysbiosis and neuropsychiatric diseases: An updated overview

The role of the gut-brain axis in mental health disorders has been extensively studied. As the oral cavity is the starting point of the digestive tract, the role that the oral microbiota plays in mental health disorders has gained recent attention. Oral microbiota can enter the bloodstream and trigger inflammatory responses or translocate to the brain through the trigeminal nerve or olfactory system. Hence, the concept of the oral microbiota-brain axis has emerged. Several hypotheses have been suggested that the oral microbiota can enter the gastrointestinal tract and affect the gut-brain axis; however, literature describing oral-brain communication remains limited. This review summarizes the characteristics of oral microbiota and its mechanisms associated with mental health disorders. Through a comprehensive examination of the relationship between oral microbiota and various neuropsychiatric diseases, such as anxiety, depression, schizophrenia, autism spectrum disorder, epilepsy, Parkinson's disease, and dementia, this review seeks to identify promising avenues of future research.

Microbiota-brain axis: Exploring the role of gut microbiota in psychiatric disorders - A comprehensive review

Mental illness is a hidden epidemic in modern science that has gradually spread worldwide. According to estimates from the World Health Organization (WHO), approximately 10% of the world's population suffers from various mental diseases each year. Worldwide, financial and health burdens on society are increasing annually. Therefore, understanding the different factors that can influence mental illness is required to formulate novel and effective treatments and interventions to combat mental illness. Gut microbiota, consisting of diverse microbial communities residing in the gastrointestinal tract, exert profound effects on the central nervous system through the gut-brain axis. The gut-brain axis serves as a conduit for bidirectional communication between the two systems, enabling the gut microbiota to affect emotional and cognitive functions. Dysbiosis, or an imbalance in the gut microbiota, is associated with an increased susceptibility to mental health disorders and psychiatric illnesses. Gut microbiota is one of the most diverse and abundant groups of microbes that have been found to interact with the central nervous system and play important physiological functions in the human gut, thus greatly affecting the development of mental illnesses. The interaction between gut microbiota and mental health-related illnesses is a multifaceted and promising field of study. This review explores the mechanisms by which gut microbiota influences mental health, encompassing the modulation of neurotransmitter production, neuroinflammation, and integrity of the gut barrier. In addition, it emphasizes a thorough understanding of how the gut microbiome affects various psychiatric conditions.

Electroacupuncture improves low-grade duodenal inflammation in FD rats by reshaping intestinal flora through the NF-κB p65/NLRP3 pyroptosis pathway

Electroacupuncture (EA) is an effective alternative for the treatment of functional dyspepsia (FD). It reduces low-grade duodenal inflammation and improves the symptoms of FD by downregulating the expression of NF-κB p65 and NLRP3, but its mechanism needs to be elucidated. To examine the regulatory effect of electroacupuncture (EA) on intestinal flora and NF-κB p65/NLRP3 pyroptosis pathway in FD rats. The FD rat model was established via multi-factor stress intervention for two weeks. The rats were randomly divided into the NC group, model group, NF-kB inhibitor group (NF-κB inhibitor BAY 11-7082 was administered), EA group, and EA + NF-kB inhibitor group. After 14 days of treatment, the rats were sacrificed, and the protein and mRNA levels of NF-κB p65, IκB, and NLRP3 in the duodenum were evaluated by Western blotting assays and real-time fluorescent quantitative PCR. The Illumina MiSeq sequencing platform was used to analyze the V4 region of the 16S rRNA gene of intestinal flora and predict functional genes. The concentration of short-chain fatty acids (SCFAs) in feces was assessed by metabolomics. EA can decrease low-grade duodenal inflammation and promote gastrointestinal motility in FD rats. This effect is mediated by inhibition of the NF-κB p65/NLRP3 pyroptosis pathway, an increase in the alpha and beta diversity of gut microbiota in the duodenum, an increase in the abundance of beneficial bacteria at the phylum and genus levels, and an increase in the content of SCFAs. The protective effect of EA against FD might involve multiple hierarchy and pathways. EA may remodel intestinal flora by inhibiting the NF-κB p65/NLRP3 pyroptosis pathway, thereby improving low-grade duodenal inflammation in FD rats.

Gut-Brain Axis: Focus on Sex Differences in Neuroinflammation

In recent years, there has been a growing interest in the concept of the "gut-brain axis". In addition to well-studied diseases associated with an imbalance in gut microbiota, such as cancer, chronic inflammation, and cardiovascular diseases, research is now exploring the potential role of gut microbial dysbiosis in the onset and development of brain-related diseases. When the function of the intestinal barrier is altered by dysbiosis, the aberrant immune system response interacts with the nervous system, leading to a state of "neuroinflammation". The gut microbiota-brain axis is mediated by inflammatory and immunological mechanisms, neurotransmitters, and neuroendocrine pathways. This narrative review aims to illustrate the molecular basis of neuroinflammation and elaborate on the concept of the gut-brain axis by virtue of analyzing the various metabolites produced by the gut microbiome and how they might impact the nervous system. Additionally, the current review will highlight how sex influences these molecular mechanisms. In fact, sex hormones impact the brain-gut microbiota axis at different levels, such as the central nervous system, the enteric nervous one, and enteroendocrine cells. A deeper understanding of the gut-brain axis in human health and disease is crucial to guide diagnoses, treatments, and preventive interventions.

Dangers of the chronic stress response in the context of the microbiota-gut-immune-brain axis and mental health: a narrative review

More than 20% of American adults live with a mental disorder, many of whom are treatment resistant or continue to experience symptoms. Other approaches are needed to improve mental health care, including prevention. The role of the microbiome has emerged as a central tenet in mental and physical health and their interconnectedness (well-being). Under normal conditions, a healthy microbiome promotes homeostasis within the host by maintaining intestinal and brain barrier integrity, thereby facilitating host well-being. Owing to the multidirectional crosstalk between the microbiome and neuro-endocrine-immune systems, dysbiosis within the microbiome is a main driver of immune-mediated systemic and neural inflammation that can promote disease progression and is detrimental to well-being broadly and mental health in particular. In predisposed individuals, immune dysregulation can shift to autoimmunity, especially in the presence of physical or psychological triggers. The chronic stress response involves the immune system, which is intimately involved with the gut microbiome, particularly in the process of immune education. This interconnection forms the microbiota-gut-immune-brain axis and promotes mental health or disorders. In this brief review, we aim to highlight the relationships between stress, mental health, and the gut microbiome, along with the ways in which dysbiosis and a dysregulated immune system can shift to an autoimmune response with concomitant neuropsychological consequences in the context of the microbiota-gut-immune-brain axis. Finally, we aim to review evidenced-based prevention strategies and potential therapeutic targets.

Mind over Microbes: Investigating the Interplay between Lifestyle Factors, Gut Microbiota, and Brain Health

BACKGROUND

The gut microbiota (GM) of the human body comprises several species of microorganisms. This microorganism plays a significant role in the physiological and pathophysiological processes of various human diseases.

METHODS

The literature review includes studies that describe causative factors that influence GM. The GM is sensitive to various factors like circadian rhythms, environmental agents, physical activity, nutrition, and hygiene that together impact the functioning and composition of the gut microbiome. This affects the health of the host, including the psycho-neural aspects, due to the interconnectivity between the brain and the gut. Hence, this paper examines the relationship of GM with neurodegenerative disorders in the context of these aforesaid factors.

CONCLUSION

Future studies that identify the regulatory pathways associated with gut microbes can provide a causal link between brain degeneration and the gut at a molecular level. Together, this review could be helpful in designing preventive and treatment strategies aimed at GM, so that neurodegenerative diseases can be treated.

Gut microbiota in women: The secret of psychological and physical well-being

The gut microbiota works in unison with the host, promoting its health. In particular, it has been shown to exert protective, metabolic and structural functions. Recent evidence has revealed the influence of the gut microbiota on other organs such as the central nervous system, cardiovascular and the endocrine-metabolic systems and the digestive system. The study of the gut microbiota is outlining new and broader frontiers every day and holds enormous innovation potential for the medical and pharmaceutical fields. Prevention and treatment of specific women's diseases involves the need to deepen the function of the gut as a junction organ where certain positive bacteria can be very beneficial to health. The gut microbiota is unique and dynamic at the same time, subject to external factors that can change it, and is capable of modulating itself at different stages of a woman's life, playing an important role that arises from the intertwining of biological mechanisms between the microbiota and the female genital system. The gut microbiota could play a key role in personalized medicine.

Gastrointestinal Dysbiosis in Neuro-Critically Ill Patients: A Systematic Review of Case-Control Studies

The human gastrointestinal tract (GIT) has a rich and pre-programmed microbiome. This microbiome is essential for physiological functions such as digestion, immunity, metabolism, and structural integrity, and of prime concern to us in conducting this study is the nervous system communication. This two-way communication between the GIT and central nervous system (CNS) is known as the gut-brain axis (GBA) and has implications for neurocritical disease. A change in any factor relating to this microbiome is known as gut dysbiosis; this can lead to aberrant communication through the GBA and in turn, can contribute to disease states. The primary objective of this study is to determine the cause-specific dysbiotic organisms in neuro-critically ill patients and their effects. We performed this study by searching published literature as per Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies that defined gastrointestinal dysbiosis in neuro-critically ill patients were retrieved using Boolean search from 2000 to 2023 via PubMed and Google Scholar and narrowed the results down to five prospective case-control studies. We performed their quality assessment. The results concluded that in neurocritical illnesses such as encephalitis, brain tumors, intracerebral hemorrhage, and ischemic stroke, fluctuations in specific microbiota correlated with disease severity and prognosis. Moreover, the inhabiting population of dysbiotic organisms in neuro-critically ill patients were different in different diseases and there were no similarities in the composition of gut microbiota in these diseases. Taking stroke patients as an example; increased Enterobacteriaceae and lower Lachnospiraceae microbiome levels were found in patients with a higher stroke dysbiosis index (SDI). Those patients who developed stroke-associated pneumonia (SAP) displayed higher levels of Enterococcus species. In conclusion, dysbiosis has a major effect on neuro-critically ill patients' disease states and dysbiotic organisms can be used as a biomarker for disease. Further prospective studies on this topic are warranted for potential neurological and prognostic correlations.

Gut–Brain Axis, Microbiota and Probiotics—Current Knowledge on Their Role in Irritable Bowel Syndrome: A Review

Irritable bowel syndrome (IBS) is a common digestive disorder with a significant impact on both individuals and society in terms of quality of life and healthcare costs. A growing body of research has identified various communication pathways between the microbiota and the brain in relation to motility disorders, with the gut–brain axis being key to the pathogenesis of IBS. Multiple factors contribute to the pathogenetic pathways in IBS, including immune mechanisms, psychosocial factors, increased oxidative stress and pro-inflammatory cytokine release, as well as genetic and hormonal factors. Increased permeability of the normal intestinal barrier allows bacterial products to access the lamina propria, providing a mechanism for perpetuating chronic inflammation and characteristic symptoms. The microbiota influences inflammatory processes in IBS by altering the balance between pro-inflammatory factors and host defence. Probiotics modulate the pathophysiological mechanisms involved in IBS by influencing the composition of the microbiota and improving intestinal motility disorders, visceral hypersensitivity, immune function of the intestinal epithelium, metabolic processes in the intestinal lumen, dysfunction of the microbiota-GBA, and are recognised as effective and safe in IBS therapy. Our study aimed to provide a comprehensive overview of the relationship between the gut–brain axis, microbiota, and IBS, based on current information.

Yeast Beta-Glucan Supplementation with Multivitamins Attenuates Cognitive Impairments in Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Randomized, Double-Blind, Placebo-Controlled Trial

This research aimed to examine the potential alleviative effects of beta-glucan administration on fatigue, unrefreshing sleep, anxiety/depression symptoms and health-related quality of life in ME/CFS. A 36-week unicenter, randomized, double-blind, placebo-controlled trial was conducted in 65 ME/CFS patients, who were randomly allocated to one of two arms to receive four capsules each one of 250 mg beta-glucan, 3.75 µg vitamin D3, 1.05 mg vitamin B6, and 7.5 mg zinc (n = 35), or matching placebo including only microcrystalline cellulose as an excipient (n = 30) once daily. The findings showed that the beta-glucan supplementation significantly improved cognitive fatigue (assessed with FIS-40 scores) after the 36-week treatment compared to the baseline (p = 0.0338). Taken together, this study presents the novel finding that yeast-derived beta-glucan may alleviate cognitive fatigue symptoms in ME/CFS. Thus, it offers valuable scientific insights into the potential use of yeast beta-glucan as a nutritional supplement and/or functional food to prevent or reduce cognitive dysfunction in patients with ME/CFS. Further interventions are warranted to validate these findings and also to delve deeper into the possible immunometabolic pathomechanisms of beta-glucans in ME/CFS.

Interactions between environmental sensitivity and gut microbiota are associated with biomarkers of stress-related psychiatric symptoms

BACKGROUND

Humans vary in their sensitivity to stressful and supportive environments and experiences. Such individual differences in environmental sensitivity are associated with mechanisms of stress-related psychiatric symptoms. In recent years, researchers have focused on bidirectional interactions in the brain-gut-microbiota axis as a neurophysiological pathway contributing to the mechanisms of stress-related psychiatric symptoms, and evidence is rapidly accumulating.

METHODS

Data on environmental sensitivity, gut microbiota, gut permeability (lipopolysaccharide-binding protein; LBP) and inflammation (C-reactive protein; CRP) were collected from 90 adults (50 % female; Mage = 42.1; SDage = 10.0). Environmental sensitivity was measured using a self-report questionnaire. Study participants' feces were analyzed, and observed operational taxonomic units for richness, Shannon's index for evenness, and phylogenetic diversity for biodiversity were evaluated as indicators of gut microbiota. In addition, participants' serum was analyzed for CRP and LBP. We investigated whether the interaction between environmental sensitivity and gut microbiota is associated with biomarkers of inflammation and gut permeability.

RESULTS

The interaction between environmental sensitivity and gut microbiota (excluding the Shannon's index) explained the levels of these biomarkers. Individuals with high environmental sensitivity displayed higher levels of CRP and LBP, when the richness and diversity of the gut microbiota was low. However, even highly susceptible individuals had lower levels of CRP and LBP, when the richness and diversity of the gut microbiota was high.

CONCLUSIONS

Our study indicates that high environmental sensitivity can be a risk factor for inflammation and gut permeability, when the gut microbiota diversity is low, suggesting a brain-gut-microbiota axis interaction.

Prevalence and factors associated with metabolic syndrome in first hospitalization for major depression disorder patients

Major depressive disorder (MDD) is a common and socially burdensome psychiatric disorder with a causal and complex relationship with metabolic syndrome (MetS), which is often co-morbid. However, the prevalence and risk factors for MetS in patients with MDD are inconclusive. The purpose of this study is to investigate the prevalence and factors influencing MetS in first hospitalization MDD patients. A total of 981 MDD patients were included. Sociodemographic and general clinical data were collected from the patients, while metabolism-related parameters were also measured, and psychological symptoms were assessed. Our study found that the prevalence of MetS in the study population was 9.68%. MDD patients with MetS had higher levels of metabolism-related parameters and more severe psychological symptoms. We identified risk factors for MetS and its severity separately: age of onset of MDD, more severe depressive symptoms, and higher thyroid stimulating hormone (TSH) levels were risk factors for the development of MetS, whereas higher TSH levels were risk factors for the severity of MetS. Our results suggest that MetS is not highly prevalent in MDD patients, but certain risk factors may increase its likelihood and severity, and that these findings could be beneficial for clinical intervention and care of MetS.

Role of the gut-microbiota-metabolite-brain axis in the pathogenesis of preterm brain injury

Brain injury, a common complication in preterm infants, includes the destruction of the key structural and functional connections of the brain and causes neurodevelopmental disorders; it has high morbidity and mortality rates. The exact mechanism underlying brain injury in preterm infants is unclear. Intestinal flora plays a vital role in brain development and the maturation of the immune system in infants; however, detailed understanding of the gut microbiota-metabolite-brain axis in preterm infants is lacking. In this review, we summarise the key mechanisms by which the intestinal microbiota contribute to neurodevelopment and brain injury in preterm infants, with special emphasis on the influence of microorganisms and their metabolites on the regulation of neurocognitive development and neurodevelopmental risks related to preterm birth, infection and neonatal necrotising enterocolitis (NEC). This review provides support for the development and application of novel therapeutic strategies, including probiotics, prebiotics, synbiotics, and faecal bacteria transplantation targeting at brain injury in preterm infants.