Gut microbiome-brain axis and inflammation in temperament, personality and psychopathology

The Legalome: Microbiology, Omics and Criminal Justice

Advances in neuromicrobiology and related omics technologies have reinforced the idea that unseen microbes play critical roles in human cognition and behaviour. Included in this research is evidence indicating that gut microbes, through direct and indirect pathways, can influence aggression, anger, irritability and antisocial behaviour. Moreover, gut microbes can manufacture chemicals that are known to compromise cognition. For example, recent court decisions in the United States and Europe acknowledge that gut microbes can produce high levels of ethanol, without consumption of alcohol by the defendants. The dismissal of driving while intoxicated charges in these cases-so-called auto-brewery syndrome-highlights the way in which microbiome knowledge will enhance the precision, objectivity and fairness of our legal systems. Here in this opinion essay, we introduce the concept of the 'legalome'-the application of microbiome and omics science to forensic psychiatry and criminal law. We argue that the rapid pace of microbial discoveries, including those that challenge ideas of free will and moral responsibility, will necessitate a reconsideration of traditional legal doctrines and justifications of retributive punishment. The implications extend beyond the courtroom, challenging us to reconsider how environmental factors-from diet to socioeconomic conditions-might shape preventative and rehabilitative efforts through their effects on the microbiome.

Temperament in Early Childhood Is Associated With Gut Microbiota Composition and Diversity

Temperament is a key predictor of human mental health and cognitive and emotional development. Although human fear behavior is reportedly associated with gut microbiome in infancy, infant gut microbiota changes dramatically during the first 5 years, when the diversity and composition of gut microbiome are established. This period is crucial for the development of the prefrontal cortex, which is involved in emotion regulation. Therefore, this study investigated the relationship between temperament and gut microbiota in 284 preschool children aged 3-4 years. Child temperament was assessed by maternal reports of the Children's Behavior Questionnaire. Gut microbiota (alpha/beta diversity and genera abundance) was evaluated using 16S rRNA sequencing of stool samples. A low abundance of anti-inflammatory bacteria (e.g., Faecalibacterium) and a high abundance of pro-inflammatory bacteria (e.g., Eggerthella, Flavonifractor) were associated with higher negative emotionality and stress response (i.e., negative affectivity, β = -0.17, p = 0.004) and lower positive emotionality and reward-seeking (i.e., surgency/extraversion, β = 0.15, p = 0.013). Additionally, gut microbiota diversity was associated with speed of response initiation (i.e., impulsivity, a specific aspect of surgency/extraversion, β = 0.16, p = 0.008). This study provides insight into the biological mechanisms of temperament and takes important steps toward identifying predictive markers of psychological/emotional risk.

Psychopathology and the Validity of Gastrointestinal Symptom Reporting as Revealed Through Cluster Analyses of MMPI-2-RF Results

BACKGROUND

Psychological state, self-reported gut symptoms, and somatic complaints are recognized relationships that can impact health assessment and subsequent treatment.

AIM

To investigate the impact of psychological state and personality on symptom self-reporting and somatization.

METHODS

Sixty-two (62) participants from the Hunter region of NSW (Australia) undertook a survey of health and lifestyle along with an MMPI-2-RF assessment of personality, psychopathology, and test-taking attitude. Participants also completed the Rome Criteria to assess functional gastrointestinal disorders (FGIDs). To assist the interpretation of MMPI-2-RF results, clustering was applied to identify similar responses and sub-cohort profiles of reporting.

RESULTS

Cluster analysis revealed four sub-cohorts, stratified by psychopathology, gut-related symptoms, and the validity of self-reported somatic complaints. Sample clustering identified one sub-cohort defined by high rates of negative affectivity and suicidal ideation. Apart from these differences, clusters were uniform for age, sex, smoking, mental health diagnoses, as well as for gut-related conditions.

CONCLUSION

Results provide further evidence of the interaction of the gut-brain axis and its relationship to serious mental health conditions. It also points to the need to assess the veracity of self-reported symptomatology that may be both pathognomonic for psychopathology but might also be a consequence of gut dysbiosis. Clustering assisted these investigations by defining distinct sub-cohorts based on participant MMPI-2-RF responses.

Probiotic and prebiotic interventions in eating disorders: A narrative review

AIMS

The review aimed to summarise and discuss findings focused on therapeutic probiotic and prebiotic interventions in eating disorders (ED).

METHODS

Using PubMed/MEDLINE, Cochrane Library, and Web of Science all published studies were retrieved until February 2023, following PRISMA guidelines. From the 111 initial studies, 5 met the inclusion criteria for this review.

RESULTS

All studies included in this narrative review were focused on anorexia nervosa (AN). Three longitudinal, randomised, controlled trials aimed to evaluate interventions with probiotics (Lactobacillus reuteri, yoghurt with Lactobacillus, and Streptococcus) in children and adolescents. These studies primarily emphasised medical outcomes and anthropometric measures following the administration of probiotics. However, the findings yielded mixed results in terms of short-term weight gain or alterations in specific immunological parameters. With a lower level of evidence, supplementation with synbiotics (probiotic + prebiotic) has been associated with improvements in microbiota diversity and attenuation of inflammatory responses.

CONCLUSIONS

Research on probiotics and prebiotics in ED is limited, primarily focussing on anorexia nervosa (AN). Their use in AN regarding medical and anthropometric outcomes needs further confirmation and future research should be warranted to assess their impact on psychological and ED symptomatology, where there is a notable gap in the existing literature.

Therapeutic potential of the ketogenic diet: A metabolic switch with implications for neurological disorders, the gut-brain axis, and cardiovascular diseases

The Ketogenic Diet (KD) is a dietary regimen that is low in carbohydrates, high in fats, and contains adequate protein. It is designed to mimic the metabolic state of fasting. This diet triggers the production of ketone bodies through a process known as ketosis. The primary objective of KD is to induce and sustain ketosis, which has been associated with numerous health benefits. Recent research has uncovered promising therapeutic potential for KD in the treatment of various diseases. This includes evidence of its effectiveness as a dietary strategy for managing intractable epilepsy, a form of epilepsy that is resistant to medication. We are currently assessing the efficacy and safety of KD through laboratory and clinical studies. This review focuses on the anti-inflammatory properties of the KD and its potential benefits for neurological disorders and the gut-brain axis. We also explore the existing literature on the potential effects of KD on cardiac health. Our aim is to provide a comprehensive overview of the current knowledge in these areas. Given the encouraging preliminary evidence of its therapeutic effects and the growing understanding of its mechanisms of action, randomized controlled trials are warranted to further explore the rationale behind the clinical use of KD. These trials will ultimately enhance our understanding of how KD functions and its potential benefits for various health conditions. We hope that our research will contribute to the body of knowledge in this field and provide valuable insights for future studies.

Beyond Auto-Brewery: Why Dysbiosis and the Legalome Matter to Forensic and Legal Psychology

International studies have linked the consumption of ultra-processed foods with a variety of non-communicable diseases. Included in this growing body of research is evidence linking ultra-processed foods to mental disorders, aggression, and antisocial behavior. Although the idea that dietary patterns and various nutrients or additives can influence brain and behavior has a long history in criminology, in the absence of plausible mechanisms and convincing intervention trials, the topic was mostly excluded from mainstream discourse. The emergence of research across nutritional neuroscience and nutritional psychology/psychiatry, combined with mechanistic bench science, and human intervention trials, has provided support to epidemiological findings, and legitimacy to the concept of nutritional criminology. Among the emergent research, microbiome sciences have illuminated mechanistic pathways linking various socioeconomic and environmental factors, including the consumption of ultra-processed foods, with aggression and antisocial behavior. Here in this review, we examine this burgeoning research, including that related to ultra-processed food addiction, and explore its relevance across the criminal justice spectrum—from prevention to intervention—and in courtroom considerations of diminished capacity. We use auto-brewery syndrome as an example of intersecting diet and gut microbiome science that has been used to refute mens rea in criminal charges. The legalome—microbiome and omics science applied in forensic and legal psychology—appears set to emerge as an important consideration in matters of criminology, law, and justice.

Importance of good hosting: reviewing the bi-directionality of the microbiome-gut-brain-axis

Gut microorganisms have been shown to significantly impact on central function and studies that have associated brain disorders with specific bacterial genera have advocated an anomalous gut microbiome as the pathophysiological basis of several psychiatric and neurological conditions. Thus, our knowledge of brain-to-gut-to microbiome communication in this bidirectional axis seems to have been overlooked. This review examines the known mechanisms of the microbiome-to-gut-to-brain axis, highlighting how brain-to-gut-to-microbiome signaling may be key to understanding the cause of disrupted gut microbial communities. We show that brain disorders can alter the function of the brain-to-gut-to-microbiome axis, which will in turn contribute to disease progression, while the microbiome-to gut-to brain direction presents as a more versatile therapeutic axis, since current psychotropic/neurosurgical interventions may have unwanted side effects that further cause disruption to the gut microbiome. A consideration of the brain-to-gut-to-microbiome axis is imperative to better understand how the microbiome-gut-brain axis overall is involved in brain illnesses, and how it may be utilized as a preventive and therapeutic tool.

The Potential Impact of the Gut Microbiota on Neonatal Brain Development and Adverse Health Outcomes

Over the past decade, microbiome research has significantly expanded in both scope and volume, leading to the development of new models and treatments targeting the gut-brain axis to mitigate the effects of various disorders. Related research suggests that interventions during the critical period from birth to three years old may yield the greatest benefits. Investigating the substantial link between the gut and brain during this crucial developmental phase raises fundamental issues about the role of microorganisms in human health and brain development. This underscores the importance of focusing on the prevention rather than the treatment of neurodevelopmental and neuropsychiatric disorders. The present review examines the gut microbiota from birth to age 3, with a particular focus on its potential relationship with neurodevelopment. This review emphasizes the immunological mechanisms underlying this relationship. Additionally, the study investigates the impact of the microbiome on cognitive development and neurobehavioral issues such as anxiety and autism. Importantly, it highlights the need to integrate mechanistic studies of animal models with epidemiological research across diverse cultures to better understand the role of a healthy microbiome in early life and the implications of dysbiosis. Furthermore, this review summarizes factors contributing to the transmission of gut microbiome-targeted therapies and their effects on neurodevelopment. Recent studies on environmental toxins known to impact neurodevelopment are also reviewed, exploring whether the microbiota may mitigate or modulate these effects.

Nutritional Criminology: Why the Emerging Research on Ultra-Processed Food Matters to Health and Justice

There is mounting concern over the potential harms associated with ultra-processed foods, including poor mental health and antisocial behavior. Cutting-edge research provides an enhanced understanding of biophysiological mechanisms, including microbiome pathways, and invites a historical reexamination of earlier work that investigated the relationship between nutrition and criminal behavior. Here, in this perspective article, we explore how this emergent research casts new light and greater significance on previous key observations. Despite expanding interest in the field dubbed 'nutritional psychiatry', there has been relatively little attention paid to its relevancy within criminology and the criminal justice system. Since public health practitioners, allied mental health professionals, and policymakers play key roles throughout criminal justice systems, a holistic perspective on both historical and emergent research is critical. While there are many questions to be resolved, the available evidence suggests that nutrition might be an underappreciated factor in prevention and treatment along the criminal justice spectrum. The intersection of nutrition and biopsychosocial health requires transdisciplinary discussions of power structures, industry influence, and marketing issues associated with widespread food and social inequalities. Some of these discussions are already occurring under the banner of 'food crime'. Given the vast societal implications, it is our contention that the subject of nutrition in the multidisciplinary field of criminology-referred to here as nutritional criminology-deserves increased scrutiny. Through combining historical findings and cutting-edge research, we aim to increase awareness of this topic among the broad readership of the journal, with the hopes of generating new hypotheses and collaborations.

Roles of Diet-Associated Gut Microbial Metabolites on Brain Health: Cell-to-Cell Interactions between Gut Bacteria and the Central Nervous System

Gut microbiota have crucial effects on brain function via the gut-brain axis. Growing evidence suggests that this interaction is mediated by signaling molecules derived from dietary components metabolized by the intestinal microbiota. Although recent studies have provided a substantial understanding of the cell-specific effects of gut microbial molecules in gut microbiome-brain research, further validation is needed. This review presents recent findings on gut microbiota-derived dietary metabolites that enter the systemic circulation and influence the cell-to-cell interactions between gut microbes and cells in the central nervous system (CNS), particularly microglia, astrocytes, and neuronal cells, ultimately affecting cognitive function, mood, and behavior. Specifically, this review highlights the roles of metabolites produced by the gut microbiota via dietary component transformation, including short-chain fatty acids, tryptophan metabolites, and bile acid metabolites, in promoting the function and maturation of brain cells and suppressing inflammatory signals in the CNS. We also discuss future directions for gut microbiome-brain research, focusing on diet-induced microbial metabolite-based therapies as possible novel approaches to mental health treatment.

Changes in the gut microbiome in the first two years of life predicted the temperament in toddlers

BACKGROUND

Temperament has been shown to be associated with the change of gut microbiome. There were no longitudinal studies to explore the role of gut microbiome changes in the development of temperament in toddlers.

METHODS

This study used longitudinal cohort to investigate the associations between changes in gut microbiome and temperament in toddlers in the first two years of life. Linear regression analysis and microbiome multivariate association with linear models were used to investigate the associations between the gut microbiome and toddlers' temperament.

RESULTS

In total, 41 toddlers were analyzed. This study found both Shannon and Chao-1 indices at birth were negatively correlated with the sadness dimension; the higher the Shannon and Chao-1 indices at 6 months, the lower the surgency/extraversion dimension scores; the higher the Shannon and Chao-1 indices at 2 years of ages, the lower the cuddliness dimension scores. After adjusting for covariates, beta diversity at birth was strongly associated with the negative affectivity dimension; beta diversity at 1 year of age was strongly associated with the activity level dimension; and beta diversity at 2 years of age was strongly associated with the discomfort and soothability dimension. Compared to Bifidobacterium cluster, this study also found Bacteroides cluster was associated with lower negative affectivity and its sub-dimensions frustration and sadness scores in toddlers.

LIMITATIONS

Generalizability of the results remains to be determined.

CONCLUSION

Results of this study confirmed the associations between changes in the gut microbiome diversity and composition in the first two years of life and toddlers' temperament.

Vitality Revisited: The Evolving Concept of Flourishing and Its Relevance to Personal and Public Health

Human flourishing, the state of optimal functioning and well-being across all aspects of an individual's life, has been a topic of philosophical and theological discussion for centuries. In the mid-20th century, social psychologists and health scientists began exploring the concept of flourishing in the context of health and high-level wellness. However, it is only in recent years, in part due to the USD 43 million Global Flourishing Study including 22 countries, that flourishing has entered the mainstream discourse. Here, we explore this history and the rapid acceleration of research into human flourishing, defined as "the relative attainment of a state in which all aspects of a person's life are good" by the Harvard University's Flourishing Program. We also explore the construct of "vitality", which refers to a sense of aliveness, energy, and motivation; we contend that this has been neglected in the flourishing movement. We explore why incorporating measures of vitality, together with a broader biopsychosocial approach, considers all dimensions of the environment across time (the total exposome), which will greatly advance research, policies, and actions to achieve human flourishing.

Constrained neuro fuzzy inference methodology for explainable personalised modelling with applications on gene expression data

Interpretable machine learning models for gene expression datasets are important for understanding the decision-making process of a classifier and gaining insights on the underlying molecular processes of genetic conditions. Interpretable models can potentially support early diagnosis before full disease manifestation. This is particularly important yet, challenging for mental health. We hypothesise this is due to extreme heterogeneity issues which may be overcome and explained by personalised modelling techniques. Thus far, most machine learning methods applied to gene expression datasets, including deep neural networks, lack personalised interpretability. This paper proposes a new methodology named personalised constrained neuro fuzzy inference (PCNFI) for learning personalised rules from high dimensional datasets which are structurally and semantically interpretable. Case studies on two mental health related datasets (schizophrenia and bipolar disorders) have shown that the relatively short and simple personalised fuzzy rules provided enhanced interpretability as well as better classification performance compared to other commonly used machine learning methods. Performance test on a cancer dataset also showed that PCNFI matches previous benchmarks. Insights from our approach also indicated the importance of two genes (ATRX and TSPAN2) as possible biomarkers for early differentiation of ultra-high risk, bipolar and healthy individuals. These genes are linked to cognitive ability and impulsive behaviour. Our findings suggest a significant starting point for further research into the biological role of cognitive and impulsivity-related differences. With potential applications across bio-medical research, the proposed PCNFI method is promising for diagnosis, prognosis, and the design of personalised treatment plans for better outcomes in the future.

Analytic Background in the Neuroscience of the Potential Project "Hippocrates"

This paper reviews the principles identified in analytic neuroscience that could be used in the setup of an international project, "Hippocrates" (H-project), named after the author of the endocrine theory of temperaments. The H-project can aim to summarize the findings in functional neurochemistry of consistent behavioural patterns (CBPs) in health (such as temperament traits) and psychopathology (symptoms of psychiatric disorders); to have systematically structured neurochemical investigations; to have an analysis of CBPs that include all ranges of behavioural histories and to have these modules complemented by regional contrasts related to climate, diets and other bio-environmental factors. The review highlights the benefits of constructivism and illustrates the contrast between constructivism and current approaches in terms of analytic and methodological aspects. (1) "Where" the neurochemical biomarkers should be measured: the review expands the range of needed measurements to out-of-brain systems, including environmental factors, and explores the concept of Specialized Extended Phenotype. (2) "What" should be measured but is missing: the review points to the need for measurement of the "Throw & Catch" neurochemical relays; behavioural and neuronal events contributing to the consistency of the CBPs but not documented in measurements. (3) Structuring the H-project's setup: the paper briefly describes a proposed earlier neurochemical framework, Functional Ensemble of Temperament that that accommodates the neurochemical continuum between temperament and symptoms of psychiatric disorders. This framework is in line with documented "Throw & Catch" neurochemical relays and can also be used to organize data about the personal and professional history of an individual.

Exiting the Anthropocene: Achieving personal and planetary health in the 21st century

Planetary health provides a perspective of ecological interdependence that connects the health and vitality of individuals, communities, and Earth's natural systems. It includes the social, political, and economic ecosystems that influence both individuals and whole societies. In an era of interconnected grand challenges threatening health of all systems at all scales, planetary health provides a framework for cross-sectoral collaboration and unified systems approaches to solutions. The field of allergy is at the forefront of these efforts. Allergic conditions are a sentinel measure of environmental impact on human health in early life-illuminating how ecological changes affect immune development and predispose to a wider range of inflammatory noncommunicable diseases (NCDs). This shows how adverse macroscale ecology in the Anthropocene penetrates to the molecular level of personal and microscale ecology, including the microbial systems at the foundations of all ecosystems. It provides the basis for more integrated efforts to address widespread environmental degradation and adverse effects of maladaptive urbanization, food systems, lifestyle behaviors, and socioeconomic disadvantage. Nature-based solutions and efforts to improve nature-relatedness are crucial for restoring symbiosis, balance, and mutualism in every sense, recognizing that both personal lifestyle choices and collective structural actions are needed in tandem. Ultimately, meaningful ecological approaches will depend on placing greater emphasis on psychological and cultural dimensions such as mindfulness, values, and moral wisdom to ensure a sustainable and resilient future.

Transepithelial Effect of Probiotics in a Novel Model of Gut Lumen to Nerve Signaling

Recent studies have shown that the gut microbiome changes brain function, behavior, and psychiatric and neurological disorders. The Gut-Brain Axis (GBA) provides a neuronal pathway to explain this. But exactly how do commensal bacteria signal through the epithelial layer of the large intestine to activate GBA nerve afferents? An in vitro model is described. We differentiated two human cell lines: Caco2Bbe1 into mature epithelium on 0.4-micron filters and then SH-SY5Y into mature neurons in 24-well plates. These were co-cultured by placing the epithelium-laden filters 1 mm above the neurons. Twenty-four hours later they were tri-cultured by apical addition of 10⁷Lactobacillus rhamnosus or Lactobacillus fermentum which settled on the epithelium. Alone, the Caco2bbe1 cells stimulated neurite outgrowth in underlying SH-SY5Y. Beyond this, the lactobacilli were well tolerated and stimulated further neurite outgrowth by 24 h post-treatment, though not passing through the filters. The results provide face validity for a first-of-kind model of transepithelial intestinal lumen-to nerve signaling. The model displays the tight junctional barrier characteristics found in the large intestine while at the same time translating stimulatory signals from the bacteria through epithelial cells to attracted neurons. The model is easy to set-up with components widely available.