Mood Disorders: The Gut Bacteriome and Beyond

Knowledge of the microbiome-gut-brain axis has revolutionized the field of psychiatry. It is now well recognized that the gut bacteriome is associated with, and likely influences, the pathogenesis of mental disorders, including major depressive disorder and bipolar disorder. However, while substantial advances in the field of microbiome science have been made, we have likely only scratched the surface in our understanding of how these ecosystems might contribute to mental disorder pathophysiology. Beyond the gut bacteriome, research into lesser explored components of the gut microbiome, including the gut virome, mycobiome, archaeome, and parasitome, is increasingly suggesting relevance in psychiatry. The contribution of microbiomes beyond the gut, including the oral, lung, and small intestinal microbiomes, to human health and pathology should not be overlooked. Increasing both our awareness and understanding of these less traversed fields of research are critical to improving the therapeutic benefits of treatments targeting the gut microbiome, including fecal microbiome transplantation, postbiotics and biogenics, and dietary intervention. Interdisciplinary collaborations integrating systems biology approaches are required to fully elucidate how these different microbial components and distinct microbial niches interact with each other and their human hosts. Excitingly, we may be at the start of the next microbiome revolution and thus one step closer to informing the field of precision psychiatry to improve outcomes for those living with mental illness.

Clinical trial: A Mediterranean diet is feasible and improves gastrointestinal and psychological symptoms in irritable bowel syndrome

BACKGROUND

Diet is fundamental to the care of irritable bowel syndrome (IBS). However, some approaches are not appropriate for individuals experiencing psychological symptoms.

AIMS

To assess feasibility of a Mediterranean diet in IBS and its impact on gastrointestinal and psychological symptoms.

METHODS

We recruited adults with Rome IV IBS and mild or moderate anxiety and/or depressive symptoms to an unblinded 6-week randomised controlled trial. Patients were randomised to Mediterranean diet counselling or habitual diet. We collected gastrointestinal and psychological symptom data, dietary data and stool samples for metagenomic sequencing.

RESULTS

We randomised 59 individuals (29 Mediterranean diet, 30 control); 48 completed the study. The Mediterranean Diet Adherence Screener score was higher in the Mediterranean diet group than controls at week 6 (7.5 [95% CI: 6.9-8.0] vs. 5.7 [5.2-6.3], p < 0.001), and there was a greater score increase than controls (2.1 [95% CI: 1.3-2.9] vs. 0.5 [95% CI: 0.1-1.0], p = 0.004), demonstrating Mediterranean diet feasibility. There was a greater proportion of gastrointestinal symptom responders in the Mediterranean diet group than controls (24/29, 83% vs. 11/30, 37%, p < 0.001) and depression responders (15/29, 52% vs. 6/30 20%, p = 0.015). There was no difference in FODMAP intake at week 6 (p = 0.51). Gastrointestinal adverse events were similar (p = 0.588). There were no differences in change in microbiome parameters between groups.

CONCLUSIONS

A Mediterranean diet is feasible in IBS and leads to improvement in gastrointestinal and psychological symptoms. Although this study was unblinded, these findings together with the broader benefits of the Mediterranean diet, provide strong impetus for future research in IBS. Australia New Zealand Clinical Trials Registry: ACTRN12620001362987.

From hype to hope: Considerations in conducting robust microbiome science

Microbiome science has been one of the most exciting and rapidly evolving research fields in the past two decades. Breakthroughs in technologies including DNA sequencing have meant that the trillions of microbes (particularly bacteria) inhabiting human biological niches (particularly the gut) can be profiled and analysed in exquisite detail. This microbiome profiling has profound impacts across many fields of research, especially biomedical science, with implications for how we understand and ultimately treat a wide range of human disorders. However, like many great scientific frontiers in human history, the pioneering nature of microbiome research comes with a multitude of challenges and potential pitfalls. These include the reproducibility and robustness of microbiome science, especially in its applications to human health outcomes. In this article, we address the enormous promise of microbiome science and its many challenges, proposing constructive solutions to enhance the reproducibility and robustness of research in this nascent field. The optimisation of microbiome science spans research design, implementation and analysis, and we discuss specific aspects such as the importance of ecological principals and functionality, challenges with microbiome-modulating therapies and the consideration of confounding, alternative options for microbiome sequencing, and the potential of machine learning and computational science to advance the field. The power of microbiome science promises to revolutionise our understanding of many diseases and provide new approaches to prevention, early diagnosis, and treatment.

Emotional symptoms and inflammatory biomarkers in childhood: Associations in two Australian birth cohorts

BACKGROUND

An increasing body of evidence supports associations between inflammation and mental health difficulties, but the onset and directionality of these relationships are unclear.

METHODS

Data sources: Barwon Infant Study (BIS; n = 500 4-year-olds) and Longitudinal Study of Australian Children (LSAC; n = 1099 10-13-year-olds).

MEASURES

Strengths and Difficulties Questionnaire emotional symptoms at 4, 10-11 and 12-13 years, and circulating levels of two inflammatory biomarkers, high-sensitivity C-reactive protein (hsCRP) and glycoprotein acetyls (GlycA), at 4 and 11-12 years.

ANALYSIS

Adjusted quantile regression models examining cross-sectional associations between emotional symptoms and inflammation in 4-year-olds (BIS), and cross-lagged associations in 10-13-year-olds (LSAC).

RESULTS

We identified a small association between higher emotional symptoms at 10-11 years and higher GlycA levels a year later (standardised coefficient β = 0.09; 95%CI: 0.02 to 0.15). Sex-stratified analyses revealed this association was stronger for boys (β = 0.13; 95%CI: 0.04 to 0.21) than girls (β = 0.01; 95%CI: -0.09 to 0.11). These associations were not observed for hsCRP. There was little evidence of an association between higher GlycA or hsCRP at 11-12 years and emotional symptoms a year later, or cross-sectional associations between emotional symptoms and hsCRP or GlycA at 4 years.

LIMITATIONS

A single time-point of biomarker collection in late childhood precluded adjustment for baseline inflammatory biomarkers.

CONCLUSIONS

Our results support the direction of association from emotional symptoms to inflammation in late childhood, with potential sex differences. This adds to the body of evidence that addressing emotional symptoms in childhood is a major priority in optimising overall health throughout the life course.

The effect of vitamin D supplementation on depressive symptoms in adults: A systematic review and meta-analysis of randomized controlled trials

Neurosteroid and immunological actions of vitamin D may regulate depression-linked physiology. Meta-analyses investigating the effect of vitamin D on depression have been inconsistent. This meta-analysis investigated the efficacy of vitamin D in reducing depressive symptoms among adults in randomized placebo-controlled trials (RCT). General and clinical populations, and studies of ill individuals with systemic diseases were included. Light therapy, co-supplementation (except calcium) and bipolar disorder were exclusionary. Databases Medline, PsycINFO, CINAHL and The Cochrane Library were searched to identify relevant articles in English published before April 2022. Cochrane risk-of-bias tool (RoB 2) and GRADE were used to appraise studies. Forty-one RCTs (n = 53,235) were included. Analyses based on random-effects models were performed with the Comprehensive Meta-analysis Software. Results for main outcome (n = 53,235) revealed a positive effect of vitamin D on depressive symptoms (Hedges' g = -0.317, 95% CI [-0.405, -0.230], p < 0.001, I2 = 88.16%; GRADE: very low certainty). RoB assessment was concerning in most studies. Notwithstanding high heterogeneity, vitamin D supplementation ≥ 2,000 IU/day appears to reduce depressive symptoms. Future research should investigate possible benefits of augmenting standard treatments with vitamin D in clinical depression. PROSPERO registration number: CRD42020149760. Funding: Finnish Medical Foundation, grant 4120 and Juho Vainio Foundation, grant 202100353.

Challenges and priorities for researching the gut microbiota in individuals living with anorexia nervosa

OBJECTIVE

The gut microbiota is implicated in several symptoms and biological pathways relevant to anorexia nervosa (AN). Investigations into the role of the gut microbiota in AN are growing, with a specific interest in the changes that occur in response to treatment. Findings suggest that microbial species may be associated with some of the symptoms common in AN, such as depression and gastrointestinal disturbances (GID). Therefore, researchers believe the gut microbiota may have therapeutic relevance. Whilst research in this field is rapidly expanding, the unique considerations relevant to conducting gut microbiota research in individuals with AN must be addressed.

METHOD

We provide an overview of the published literature investigating the relationship between the gut microbiota and symptoms and behaviors present in AN, discuss important challenges in gut microbiota research, and offer recommendations for addressing these. We conclude by summarizing research design priorities for the field to move forward.

RESULTS

Several ways exist to reduce participant burden and accommodate challenges when researching the gut microbiota in individuals with AN.

DISCUSSION

Recommendations from this article are foreseen to encourage scientific rigor and thoughtful protocol planning for microbiota research in AN, including ways to reduce participant burden. Employing such methods will contribute to a better understanding of the role of the gut microbiota in AN pathophysiology and treatment.

PUBLIC SIGNIFICANCE

The field of gut microbiota research is rapidly expanding, including the role of the gut microbiota in anorexia nervosa. Thoughtful planning of future research will ensure appropriate data collection for meaningful interpretation while providing a positive experience for the participant. We present current challenges, recommendations for research design and priorities to facilitate the advancement of research in this field.

Pre-pregnancy obesity is associated with greater systemic inflammation and increased risk of antenatal depression

BACKGROUND

Pre-pregnancy obesity is an emerging risk factor for perinatal depression. However, the underlying mechanisms remain unclear. We investigated the association between pre-pregnancy body mass index (BMI) and perinatal depressive symptoms in a large population-based pre-birth cohort, the Barwon Infant Study. We also assessed whether the levels of circulating inflammatory markers during pregnancy mediated this relationship.

METHODS

Depressive symptoms were assessed in 883 women using the Edinburgh Postnatal Depression Scale (EPDS) and psychological stress using the Perceived Stress Scale (PSS) at 28 weeks gestation and 4 weeks postpartum. Glycoprotein acetyls (GlycA), high-sensitivity C-reactive protein (hsCRP) and cytokines were assessed at 28 weeks gestation. We performed regression analyses, adjusted for potential confounders, and investigated mediation using nested counterfactual models.

RESULTS

The estimated effect of pre-pregnancy obesity (BMI ≥ 30 kg/m2) on antenatal EPDS scores was 1.05 points per kg/m2 increase in BMI (95% CI: 0.20, 1.90; p = 0.02). GlycA, hsCRP, interleukin (IL) -1ra and IL-6 were higher in women with obesity, compared to healthy weight women, while eotaxin and IL-4 were lower. Higher GlycA was associated with higher EPDS and PSS scores and partially mediated the association between pre-pregnancy obesity and EPDS/PSS scores in unadjusted models, but this association attenuated upon adjustment for socioeconomic adversity. IL-6 and eotaxin were negatively associated with EPDS/PSS scores, however there was no evidence for mediation.

CONCLUSIONS

Pre-pregnancy obesity increases the risk of antenatal depressive symptoms and is also associated with systemic inflammation during pregnancy. While discrete inflammatory markers are associated with antenatal depressive symptoms and perceived stress, their role in mediating the effects of pre-pregnancy obesity on antenatal depression requires further investigation.

Comorbidity between major depressive disorder and physical diseases: a comprehensive review of epidemiology, mechanisms and management

Populations with common physical diseases - such as cardiovascular diseases, cancer and neurodegenerative disorders - experience substantially higher rates of major depressive disorder (MDD) than the general population. On the other hand, people living with MDD have a greater risk for many physical diseases. This high level of comorbidity is associated with worse outcomes, reduced adherence to treatment, increased mortality, and greater health care utilization and costs. Comorbidity can also result in a range of clinical challenges, such as a more complicated therapeutic alliance, issues pertaining to adaptive health behaviors, drug-drug interactions and adverse events induced by medications used for physical and mental disorders. Potential explanations for the high prevalence of the above comorbidity involve shared genetic and biological pathways. These latter include inflammation, the gut microbiome, mitochondrial function and energy metabolism, hypothalamic-pituitary-adrenal axis dysregulation, and brain structure and function. Furthermore, MDD and physical diseases have in common several antecedents related to social factors (e.g., socioeconomic status), lifestyle variables (e.g., physical activity, diet, sleep), and stressful live events (e.g., childhood trauma). Pharmacotherapies and psychotherapies are effective treatments for comorbid MDD, and the introduction of lifestyle interventions as well as collaborative care models and digital technologies provide promising strategies for improving management. This paper aims to provide a detailed overview of the epidemiology of the comorbidity of MDD and specific physical diseases, including prevalence and bidirectional risk; of shared biological pathways potentially implicated in the pathogenesis of MDD and common physical diseases; of socio-environmental factors that serve as both shared risk and protective factors; and of management of MDD and physical diseases, including prevention and treatment. We conclude with future directions and emerging research related to optimal care of people with comorbid MDD and physical diseases.

Differences in the gut microbiome across typical ageing and in Parkinson's disease

The microbiota-gut-brain axis' role in Parkinson's disease (PD) pathophysiology, and how this differs from typical ageing, is poorly understood. Presently, gut-bacterial diversity, taxonomic abundance and metabolic bacterial pathways were compared across healthy young (n = 22, 18-35 years), healthy older (n = 33, 50-80 years), and PD groups (n = 18, 50-80 years) using shotgun sequencing and compositional data analysis. Associations between the gut-microbiome and PD symptoms, and between lifestyle factors (fibre intake, physical activity, and sleep) and the gut-microbiome were conducted. Alpha-diversity did not differ between PD participants and older adults, whilst beta-diversity differed between these groups. Lower abundance of Butyricimonas synergistica, a butyrate-producer, was associated with worse PD non-motor symptoms in the PD group. Regarding typical ageing, Bifidobacterium bifidum, was greater in the younger compared to older group, with no difference between the older and PD group. Abundance of metabolic pathways related to butyrate production did not differ among the groups, while 100 other metabolic pathways differed among the three groups. Sleep efficiency was positively associated with Roseburia inulinivorans in the older group. These results highlight the relevance of gut-microbiota to PD and that reduced butyrate-production may be involved with PD pathophysiology. Future studies should account for lifestyle factors when investigating gut-microbiomes across ageing and in PD.

Feasibility, Acceptability, and Safety of Faecal Microbiota Transplantation in the Treatment of Major Depressive Disorder: A Pilot Randomized Controlled Trial

OBJECTIVES

Perturbations of the intestinal microbiota have been associated with mental health disorders, including major depressive disorder (MDD). Therefore, faecal microbiota transplantation (FMT) holds promise as a microbiota-modulating treatment for MDD. Yet, to date, there are no published controlled studies evaluating the use of FMT for MDD. This study aimed to address this gap by evaluating the feasibility, acceptability, and safety of FMT for MDD.

METHODS

The study was an 8-week, double-blind, 2:1 parallel group, randomized controlled pilot trial (n = 15) of enema-delivered FMT (n = 10) compared with a placebo enema (n = 5) in adults with moderate-to-severe MDD.

RESULTS

Recruitment was completed within 2 months, with 0% attrition and 100% attendance at key study appointments. There were no major protocol deviations. The placebo and blinding strategies were considered successful; nurses and participants correctly guessing their treatment allocation at a rate similar to that anticipated by chance. No serious or severe adverse events were reported in either group, and there were no significant differences in mild-to-moderate adverse events between groups (median of 2 adverse events per participant reported in both groups). Furthermore, the 12/15 participants who completed the Week 2 participant satisfaction survey agreed or strongly agreed that the enema delivery was tolerable and that they would have the treatment again if required. Whilst the study was not designed to measure clinical outcomes, exploratory data also suggested that the active FMT treatment may lead to improvements in gastrointestinal symptoms and quality of life in this population, noting that irritable bowel syndrome is commonly comorbid with MDD.

CONCLUSIONS

All feasibility targets were met or exceeded. This study found that enema-delivered FMT is feasible, acceptable, well-tolerated, and safe in patients with MDD. The findings of this study support further research to evaluate clinical efficacy, and the use of this protocol is supported.

A cross-sectional investigation of cognition and epileptiform discharges in juvenile absence epilepsy

OBJECTIVES

Despite the prevalence of cognitive symptoms in the idiopathic generalized epilepsies (IGEs), cognitive dysfunction in juvenile absence epilepsy (JAE), a common yet understudied IGE subtype, remains poorly understood. This descriptive study provides a novel, comprehensive characterization of cognitive functioning in a JAE sample and examines the relationship between cognition and 24-h epileptiform discharge load.

METHOD

Forty-four individuals diagnosed with JAE underwent cognitive assessment using Woodcock Johnson III Test of Cognitive Abilities with concurrent 24-h ambulatory EEG monitoring. Generalized epileptiform discharges of any length, and prolonged generalized discharges ≥3 s were quantified across wakefulness and sleep. The relationship between standardized cognitive scores and epileptiform discharges was assessed through regression models.

RESULTS

Cognitive performances in overall intellectual ability, acquired comprehension-knowledge, processing speed, long-term memory storage and retrieval, and executive processes were 0.63-1.07 standard deviation (SD) units lower in the JAE group compared to the population reference mean, adjusted for educational attainment. Prolonged discharges (≥3 s) were recorded in 20 patients (47.6%) from 42 available electroencephalography (EEG) studies and were largely unreported. Duration and number of prolonged discharges were associated with reduced processing speed and long-term memory storage and retrieval.

SIGNIFICANCE

Cognitive dysfunction is seen in patients with JAE across various cognitive abilities, including those representing more stable processes like general intellect. During 24-h EEG, prolonged epileptiform discharges are common yet underreported in JAE despite treatment, and they show moderate effects on cognitive abilities. If epileptiform burden is a modifiable predictor of cognitive dysfunction, therapeutic interventions should consider quantitative 24-h EEG with routine neuropsychological screening. The growing recognition of the spectrum of neuropsychological comorbidities of IGE highlights the value of multidisciplinary approaches to explore the causes and consequences of cognitive deficits in epilepsy.

Unlocking Modifiable Risk Factors for Alzheimer's Disease: Does the Oral Microbiome Hold Some of the Keys?

Advancing age is recognized as the primary risk factor for Alzheimer's disease (AD); however approximately one third of dementia cases are attributable to modifiable risk factors such as hypertension, diabetes, smoking, and obesity. Recent research also implicates oral health and the oral microbiome in AD risk and pathophysiology. The oral microbiome contributes to the cerebrovascular and neurodegenerative pathology of AD via the inflammatory, vascular, neurotoxic, and oxidative stress pathways of known modifiable risk factors. This review proposes a conceptual framework that integrates the emerging evidence regarding the oral microbiome with established modifiable risk factors. There are numerous mechanisms by which the oral microbiome may interact with AD pathophysiology. Microbiota have immunomodulatory functions, including the activation of systemic pro-inflammatory cytokines. This inflammation can affect the integrity of the blood-brain barrier, which in turn modulates translocation of bacteria and their metabolites to brain parenchyma. Amyloid-β is an antimicrobial peptide, a feature which may in part explain its accumulation. There are microbial interactions with cardiovascular health, glucose tolerance, physical activity, and sleep, suggesting that these modifiable lifestyle risk factors of dementia may have microbial contributors. There is mounting evidence to suggest the relevance of oral health practices and the microbiome to AD. The conceptual framework presented here additionally demonstrates the potential for the oral microbiome to comprise a mechanistic intermediary between some lifestyle risk factors and AD pathophysiology. Future clinical studies may identify specific oral microbial targets and the optimum oral health practices to reduce dementia risk.

Safety and feasibility of faecal microbiota transplant for major depressive disorder: study protocol for a pilot randomised controlled trial

BACKGROUND

Mental disorders, including major depressive disorder (MDD), are a leading cause of non-fatal burden of disease globally. Current conventional treatments for depression have significant limitations, and there have been few new treatments in decades. The microbiota-gut-brain-axis is now recognised as playing a role in mental and brain health, and promising preclinical and clinical data suggest Faecal Microbiota Transplants (FMT) may be efficacious for treating a range of mental illnesses. However, there are no existing published studies in humans evaluating the efficacy of FMT for MDD.

METHODS AND DESIGN

This protocol describes an 8-week, triple-blind, 2:1 parallel group, randomised controlled pilot trial (n = 15), of enema-delivered FMT treatment (n = 10) compared with a placebo enema (n = 5) in adults with moderate-to-severe MDD. There will be a further 26-week follow-up to monitor longer-term safety. Participants will receive four FMT or placebo enemas over four consecutive days. The primary aims of the study are to evaluate feasibility and safety of FMT as an adjunctive treatment for MDD in adults. Changes in gut microbiota will be assessed as a secondary outcome. Other data will be collected, including changes in depression and anxiety symptoms, and safety parameters.

DISCUSSION

Modification of the microbiota-gut-brain axis via FMT is a promising potential treatment for MDD, but there are no published rigorous clinical trials evaluating its use. If this study finds that our FMT strategy is safe and feasible, a larger fully powered RCT is planned. Further high-quality research in this field is urgently needed to address unmet need.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry: ACTRN12621000932864.

Effects of a low FODMAP diet on the colonic microbiome in irritable bowel syndrome: a systematic review with meta-analysis

BACKGROUND

A low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet is increasingly used to manage symptoms in irritable bowel syndrome (IBS). Although this approach may alter the colonic microbiome, the nature of these changes has not been comprehensively synthesized.

OBJECTIVES

The aim of this study was to conduct a systematic review with meta-analysis of randomized controlled trials examining the impact of a low FODMAP diet on the composition and function of the microbiome in patients with IBS.

METHODS

A systematic search was conducted for randomized controlled trials evaluating the effects of a low FODMAP diet on the colonic microbiome in patients with IBS in MEDLINE, EMBASE, CENTRAL, and Web of Science from inception to April 2022. Outcomes included diversity of the microbiome, specific bacterial abundances, fecal SCFA concentration, and fecal pH. For fecal SCFA concentrations and pH, meta-analyses were performed via a random-effects model.

RESULTS

Nine trials involving 403 patients were included. There were no clear effects of the low FODMAP diet on diversity of the microbiome. A low FODMAP diet consistently led to lower abundance of Bifidobacteria, but there were no clear effects on diversity of the microbiome or abundances of other specific taxa. There were no differences in total fecal SCFA concentration between the low FODMAP diet and control diets (standardized mean difference: -0.25; 95% CI: -0.63, 0.13; P = 0.20), nor were there differences for fecal concentrations of specific SCFAs or fecal pH.

CONCLUSIONS

In patients with IBS, the effects of a low FODMAP diet on the colonic microbiome appear to be specific to Bifidobacteria with no consistent impacts on other microbiome metrics, including diversity, fecal SCFA concentrations, and fecal pH. Further, adequately powered trials are needed to confirm these findings.This review was registered at https://www.crd.york.ac.uk/prospero/ as CRD42020192243.

To the Gut Microbiome and Beyond: The Brain-First or Body-First Hypothesis in Parkinson's Disease

There is continued debate regarding Parkinson’s disease etiology and whether it originates in the brain or begins in the gut. Recently, evidence has been provided for both, with Parkinson’s disease onset presenting as either a “body-first” or “brain-first” progression. Most research indicates those with Parkinson’s disease have an altered gut microbiome compared to controls. However, some studies do not report gut microbiome differences, potentially due to the brain or body-first progression type. Based on the etiology of each proposed progression, individuals with the body-first progression may exhibit altered gut microbiomes, i.e., where short-chain fatty acid producing bacteria are reduced, while the brain-first progression may not. Future microbiome research should consider this hypothesis and investigate whether gut microbiome differences exist between each type of progression. This may further elucidate the impact of the gut microbiome in Parkinson’s disease and show how it may not be homogenous across individuals with Parkinson’s disease.

Maternal inflammatory and omega-3 fatty acid pathways mediate the association between socioeconomic disadvantage and childhood cognition

Poor cognitive outcomes in early childhood predict poor educational outcomes and diminished health over the life course. We sought to investigate (i) whether maternal metabolites predict child cognition, and (ii) if maternal metabolomic profile mediates the relationship between environmental exposures and child cognition. Metabolites were measured using nuclear magnetic resonance-based metabolomics in pregnant women from a population-derived birth cohort. Child cognition was measured at age 2 years. In 662 mother-child pairs, elevated inflammatory markers (β = -2.62; 95% CI -4.10, -1.15; P = 0.0005) and lower omega-3 fatty acid-related metabolites (β = 0.49; 95% CI 0.09, 0.88; P = 0.02) in the mother were associated with lower child cognition and partially mediated the association between lower child cognition and multiple risk factors common to socioeconomic disadvantage. Modifying maternal prenatal metabolic pathways related to inflammation and omega-3 fatty acids may offset the adverse associations between prenatal risk factors related to socioeconomic disadvantage and low child cognition.

A systematic review of gut microbiota composition in observational studies of major depressive disorder, bipolar disorder and schizophrenia

The emerging understanding of gut microbiota as 'metabolic machinery' influencing many aspects of physiology has gained substantial attention in the field of psychiatry. This is largely due to the many overlapping pathophysiological mechanisms associated with both the potential functionality of the gut microbiota and the biological mechanisms thought to be underpinning mental disorders. In this systematic review, we synthesised the current literature investigating differences in gut microbiota composition in people with the major psychiatric disorders, major depressive disorder (MDD), bipolar disorder (BD) and schizophrenia (SZ), compared to 'healthy' controls. We also explored gut microbiota composition across disorders in an attempt to elucidate potential commonalities in the microbial signatures associated with these mental disorders. Following the PRISMA guidelines, databases were searched from inception through to December 2021. We identified 44 studies (including a total of 2510 psychiatric cases and 2407 controls) that met inclusion criteria, of which 24 investigated gut microbiota composition in MDD, seven investigated gut microbiota composition in BD, and 15 investigated gut microbiota composition in SZ. Our syntheses provide no strong evidence for a difference in the number or distribution (α-diversity) of bacteria in those with a mental disorder compared to controls. However, studies were relatively consistent in reporting differences in overall community composition (β-diversity) in people with and without mental disorders. Our syntheses also identified specific bacterial taxa commonly associated with mental disorders, including lower levels of bacterial genera that produce short-chain fatty acids (e.g. butyrate), higher levels of lactic acid-producing bacteria, and higher levels of bacteria associated with glutamate and GABA metabolism. We also observed substantial heterogeneity across studies with regards to methodologies and reporting. Further prospective and experimental research using new tools and robust guidelines hold promise for improving our understanding of the role of the gut microbiota in mental and brain health and the development of interventions based on modification of gut microbiota.

Gut Microbiome Diversity and Composition Are Associated with Habitual Dairy Intakes: A Cross-Sectional Study in Men

BACKGROUND

At a population level, the relation between dairy consumption and gut microbiome composition is poorly understood.

OBJECTIVES

We sought to study the cross-sectional associations between individual dairy foods (i.e., milk, yogurt, and cheese), as well as total dairy intake, and the gut microbiome composition in a large, representative sample of men living in south-eastern Australia.

METHODS

Data on 474 men (mean ± SD: 64.5 ± 13.5 y old) from the Geelong Osteoporosis Study were used to assess the cross-sectional association between dairy consumption and gut microbiome. Information on dairy intake was self-reported. Men were categorized as consumers and nonconsumers of milk, yogurt, cheese, and high- and low-fat milk. Milk, yogurt, and cheese intakes were summed to calculate the total dairy consumed per day and categorized into either low (<2.5 servings/d) or high (≥2.5 servings/d) total dairy groups. Fecal samples were analyzed using bacterial 16S ribosomal RNA (rRNA) gene sequencing. After assessment of α and β diversity, differential abundance analysis was performed to identify bacterial taxa associated with each of milk, yogurt, and cheese consumption compared with nonconsumption, low compared with high total dairy, and low- compared with high-fat milk consumption. All analyses were adjusted for potential confounders.

RESULTS

α Diversity was not associated with consumption of any of the dairy groups. Differences in β diversity were observed between milk and yogurt consumption compared with nonconsumption. Taxa belonging to the genera Ruminococcaceae UCG-010 and Bifidobacterium showed negative and weak positive associations with milk consumption, respectively. A taxon from the genus Streptococcus was positively associated with yogurt consumption, whereas a taxon from the genus Eisenbergiella was negatively associated with cheese consumption. No specific taxa were associated with low- compared with high-fat milk nor low compared with high total dairy consumption.

CONCLUSIONS

In men, community-level microbiome differences were observed between consumers and nonconsumers of milk and yogurt. Bacterial taxon-level associations were detected with milk, yogurt, and cheese consumption. Total dairy consumption was not associated with any microbiome measures, suggesting that individual dairy foods may have differential roles in shaping the gut microbiome in men.

The role of diet quality and dietary patterns in predicting muscle mass and function in men over a 15-year period

A growing body of evidence suggests that diet quality may predict muscle health. This study found that a "Traditional" dietary pattern predicted greater muscle mass, and an anti-inflammatory diet predicted greater muscle mass and better muscle function over 15 years. These findings reinforce the importance of optimising dietary behaviours for healthy ageing.

INTRODUCTION

Research investigating the roles of individual nutrients in muscle health fails to account for the synergistic relationships between foods and nutrients. This study aimed to investigate the predictive value of diet quality and dietary patterns for muscle mass and function in men over a 15-year period.

METHODS

This longitudinal study was conducted in 522 men from the Geelong Osteoporosis Study with complete dietary and muscle mass or muscle function data at both baseline and 15-year follow-up assessments. Dietary exposures were extracted from food frequency questionnaires and included the Australian Recommended Food Score, the Dietary Inflammatory Index (DII®), and three a posteriori dietary patterns: Plant-focused, Western, and Traditional (Anglo-Australian). Outcome variables included dual-energy X-ray absorptiometry-derived skeletal muscle index (SMI) and muscle function measured with the timed up-and-go (TUG) test.

RESULTS

An anti-inflammatory diet and higher scores on a Traditional dietary pattern both predicted greater SMI ((B: -0.04 (95%CI -0.08, -0.00) kg/m²) and (B: 0.12 (95%CI 0.04, 0.20) kg/m²), respectively), while a pro-inflammatory diet predicted slower TUG (B: 0.11 (95%CI 0.001, 0.21) sec) over the 15-year follow-up period. These associations remained significant following adjustment for confounding variables. There were no associations observed for other dietary exposures.

CONCLUSION

A Traditional dietary pattern higher in vegetables, wholegrain cereals, and animal protein was associated with greater skeletal muscle mass, and an anti-inflammatory diet, also rich in vegetables, fruit, and wholegrain cereals, was associated with greater skeletal muscle mass and better muscle function over 15 years.

Inhibition, excitation and bilateral transfer following a unilateral complex finger-tapping task in young and older adults

Neuroplasticity underpins motor learning, with abnormal neuroplasticity related to age-associated motor declines. Bilateral transfer of motor learning, through rehabilitation, may mitigate these declines; however, the magnitude of transfer may be reduced in older populations. This study investigated excitatory and inhibitory pathways in the trained and untrained hemispheres following unilateral training of a complex finger-tapping task across ageing. Fifteen young (26.2 ± 3.8 years) and 11 older adults (63.7 ± 15.4 years) received transcranial magnetic stimulation, although surface electromyography was recorded from the extensor digitorum communis (EDC) and abductor pollicis brevis (APB), before and after practicing a complex finger-tapping task with the dominant hand. Excitability, inhibition (expressed as percent change scores from pre- to post-training), motor task performance and bilateral transfer were assessed between groups. Investigation of hemispheric differences within each group was completed for measures that significantly differed between groups. There were no between-group differences in task performance or bilateral transfer, with task performance improving post-training irrespective of group for both hands (p < 0.05). Pre- to post-inhibition change scores of the untrained EDC muscle increased (p = 0.034) in older compared with younger adults, indicating reduced inhibition in older adults. Inhibition change scores significantly differed between hemispheres for the young group only (p = 0.037). Only the younger group presented with hemispheric lateralisation, providing some support for the Hemispheric Asymmetry Reduction in OLDer adults (HAROLD) hypothesis. Whether this reduction is evidence of de-differentiation or compensation will need to be confirmed with additional measures.

Maternal prenatal gut microbiota composition predicts child behaviour

BACKGROUND

Murine studies demonstrate that maternal prenatal gut microbiota influences brain development and behaviour of offspring. No human study has related maternal gut microbiota to behavioural outcomes during early life. This study aimed to evaluate relationships between the prenatal faecal microbiota, prenatal diet and childhood behaviour.

METHODS

A sub-cohort of 213 mothers and 215 children were selected from a longitudinal pre-birth cohort. Maternal prenatal exposure measures collected during the third trimester included the faecal microbiota (generated using 16S rRNA amplicon sequencing), and dietary intake. The behavioural outcome used the Childhood Behaviour Checklist at age two. Models were adjusted for prenatal diet, smoking, perceived stress, maternal age and sample batch.

FINDINGS

We found evidence that the alpha diversity of the maternal faecal microbiota during the third trimester of pregnancy predicts child internalising behaviour at two years of age (-2·74, (-4·71, -0·78), p = 0·01 (Wald test), R2=0·07). Taxa from butyrate-producing families, Lachnospiraceae and Ruminococcaceae, were more abundant in mothers of children with normative behaviour. A healthy prenatal diet indirectly related to decreased child internalising behaviours via higher alpha diversity of maternal faecal microbiota.

INTERPRETATION

These findings support animal studies showing that the composition of maternal prenatal gut microbiota is related to offspring brain development and behaviour. Our findings highlight the need to evaluate potential impacts of the prenatal gut microbiota on early life brain development.

FUNDING

This study was funded by the National Health and Medical Research Council of Australia (1082307, 1147980), Murdoch Children's Research Institute, Barwon Health and Deakin University.

Gastrointestinal symptoms following treatment for anorexia nervosa: A systematic literature review

OBJECTIVE

Gastrointestinal (GI) disturbances are a frequent and burdensome experience for patients with anorexia nervosa (AN). How GI symptoms respond to current interventions is not well characterized, yet is critical to facilitate treatment success, and to inform the development of new treatments for AN. Therefore, the aim of this systematic review was to identify which treatments are effective in improving GI symptoms in patients with AN.

METHOD

A systematic search for studies of AN treatments measuring GI symptoms pre- and post-treatment was conducted in May 2020 (PROSPERO ID: CRD42020181328). After removal of duplicates, title and abstracts of 3,370 studies were screened. Methodological quality was assessed using National Institute of Health Quality Assessment Tool.

RESULTS

Following full-text screening, 13 studies (12 observational studies and 1 randomized double-blind placebo-controlled trial) with 401 participants met eligibility criteria and were included. All observational studies included a component of nutritional rehabilitation, with half (n = 6) involving concurrent psychological treatment. The randomized controlled trial reported a drug therapy. Eleven studies reported an improvement in all (n = 6) or at least one (n = 5) patient-reported GI symptom following treatment. Two studies reported no change. Methodological quality was fair or poor across all studies.

DISCUSSION

This is the first systematic review to synthesize available evidence on the trajectory of patient-reported GI symptoms from commencement to end of treatment for AN. The results suggest that most studies showed improvement in one or more GI symptom in response to current treatments. Future therapeutic approaches should consider GI symptoms within their design for optimal treatment adherence and outcomes.

Diet and Mental Health

There is accumulating evidence from observational and intervention studies in nutritional psychiatry regarding the importance of diet for mental health outcomes across the lifespan. Here, we synthesise this evidence, including findings from large meta-analyses showing cross-sectional and prospective associations between diet quality and mental health, even following adjustment for relevant confounding factors. Potential mechanistic pathways underpinning these associations include those of the gut-brain axis, demonstrated mostly in animal models. Dietary fibre is an important component of healthy diet and may be relevant for common mental disorders, with some studies showing a dose-dependent relationship between fibre intake and risk of depression. The potential contribution of nutraceuticals is also discussed, such as omega-3 fatty acids, vitamins, minerals, and psychobiotics. We consider the relevance of special diets such as the ketogenic diet and food sensitivities in the management of severe mental illness (e.g., anorexia nervosa) and brain disease (e.g., Alzheimer's disease). Given the relatively early nature of research in nutritional psychiatry, there remain a number of challenges to its translation into clinical practice. These span individual, clinical, and societal domains. We conclude with a discussion of micro- and macroeconomic factors which may be considered in the successful application of nutritional psychiatry research to improve public health.

Possible use of fermented foods in rehabilitation of anorexia nervosa: the gut microbiota as a modulator

Anorexia nervosa is a serious psychiatric disorder with high morbidity and mortality rate. Evidence for the optimal psychopharmacological approach to managing the disorder remains limited, with nutritional treatment, focused on weight restoration through the consumption of high energy diet, regarded as one of the fundamental steps in treatment. The human gut microbiome is increasingly recognised for its proposed role in gastrointestinal, metabolic, immune and mental health, all of which may be compromised in individuals with anorexia nervosa. Dietary intake plays an important role in shaping gut microbiota composition, whilst the use of fermented foods, foods with potential psychobiotic properties that deliver live bacteria, bacterial metabolites, prebiotics and energy, have been discussed to a lesser extent. However, fermented foods are of increasing interest due to their potential capacity to affect gut microbiota composition, provide beneficial bacterial metabolites, and confer beneficial outcomes to host health. This review provides an overview of the role of the gut microbiota in relation to the disease pathology in anorexia nervosa and especially focuses on the therapeutic potential of fermented foods, proposed here as a recommended addition to the current nutritional treatment protocols warranting further investigation.

Associations between dairy consumption and constipation in adults: A cross-sectional study

OBJECTIVE

The current study aimed to assess the association between dairy consumption and constipation in the general adult population.

DESIGN

Data from the Geelong Osteoporosis Study were used to assess the association between dairy consumption and constipation in women (n=632) and men (n=609). Information on milk, yogurt and cheese, and constipation were self-reported. Total dairy was calculated by summing the intake of milk, yogurt and cheese and expressed as servings per day. Multivariable logistic regression models adjusted for irritable bowel syndrome, major depressive disorders, mobility, body mass index, age and fibre intake were used to examine the odds ratio (OR) and 95% confidence interval (CI) between the consumption of categories of total dairy, milk, yogurt, cheese, and constipation.

RESULTS

In women, consumption of 1-2 servings/d of total dairy was associated with reduced odds for constipation (OR: 0.49; 95% CI: 0.26-0.90; P=0.021) compared to consuming <1 serving/d of total dairy after adjusting for covariates. Also, consumption of 1-4 servings/d of milk was associated with marginally reduced odds for constipation (OR: 0.63; 95% CI: 0.39-1.02; P=0.058) compared to women who consumed <1 serving/d of milk after adjusting for covariates. There were no significant associations detected between other types of dairy consumption and constipation in women, and none in men.

CONCLUSION

In women, consumption of moderate amounts of dairy is associated with reduced odds for constipation whereas in men no associations were detected between dairy consumption and constipation. Further studies are warranted to confirm results.

Diet quality and a traditional dietary pattern predict lean mass in Australian women: Longitudinal data from the Geelong Osteoporosis Study

Low muscle mass is associated with reduced independence and increased risk for falls and fractures. Identification of modifiable risk factors for low muscle mass is thus imperative. This study aimed to examine the longitudinal relationship between both diet quality and patterns and lean mass in Australian women. Data from n = 494 participants of the Geelong Osteoporosis Study's 10- and 15-year women's follow-ups were used (conducted in 2004-08 and 2011-14, respectively), and participants were aged 21-89 years. Self-reported lifestyle and demographics were collected, and food frequency questionnaire data informed the dietary exposure variables: the Australian Recommended Food Score (ARFS); the Dietary Inflammatory Index (DII); and a posteriori dietary patterns. The outcome, Skeletal Muscle Index (SMI), was calculated from DXA-derived appendicular lean mass (ALM) relative to height (ALM kg/m2). Analyses employed Generalised Estimating Equations. A higher ARFS score positively predicted SMI over 5-years, and adjustments for age and physical activity did not attenuate this relationship (B:0.044, (95%CI 0.004, 0.084) kg/m2). Following adjustment, both an anti-inflammatory diet (B:-0.034, (95%CI -0.070, -0.002) kg/m2) and a 'traditional' dietary pattern predicted higher SMI (B:0.081, (95%CI 0.004, 0.158) kg/m2). No other associations were observed. Our study reinforces the importance of diet quality for healthy, aging muscle mass. Furthermore, a less inflammatory diet and a diet comprising a wide variety of plant and animal foods may be conducive to maintenance of muscle mass in women. Further studies investigating diet quality's impact on various muscle health measures over longer time periods are warranted.

Ultraprocessed food and chronic noncommunicable diseases: A systematic review and meta-analysis of 43 observational studies

This systematic review and meta-analysis investigated the association between consumption of ultraprocessed food and noncommunicable disease risk, morbidity and mortality. Forty-three observational studies were included (N = 891,723): 21 cross-sectional, 19 prospective, two case-control and one conducted both a prospective and cross-sectional analysis. Meta-analysis demonstrated consumption of ultraprocessed food was associated with increased risk of overweight (odds ratio: 1.36; 95% confidence interval [CI], 1.23-1.51; P < 0.001), obesity (odds ratio: 1.51; 95% CI, 1.34-1.70; P < 0.001), abdominal obesity (odds ratio: 1.49; 95% CI, 1.34-1.66; P < 0.0001), all-cause mortality (hazard ratio: 1.28; 95% CI, 1.11-1.48; P = 0.001), metabolic syndrome (odds ratio: 1.81; 95% CI, 1.12-2.93; P = 0.015) and depression in adults (hazard ratio: 1.22; 95% CI, 1.16-1.28, P < 0.001) as well as wheezing (odds ratio: 1.40; 95% CI, 1.27-1.55; P < 0.001) but not asthma in adolescents (odds ratio: 1.20; 95% CI, 0.99-1.46; P = 0.065). In addition, consumption of ultraprocessed food was associated with cardiometabolic diseases, frailty, irritable bowel syndrome, functional dyspepsia and cancer (breast and overall) in adults while also being associated with metabolic syndrome in adolescents and dyslipidaemia in children. Although links between ultraprocessed food consumption and some intermediate risk factors in adults were also highlighted, further studies are required to more clearly define associations in children and adolescents. STUDY REGISTRATION: Prospero ID: CRD42020176752.

The effects of dairy and dairy derivatives on the gut microbiota: a systematic literature review

The effects of dairy and dairy-derived products on the human gut microbiota remains understudied. A systematic literature search was conducted using Medline, CINAHL, Embase, Scopus, and PubMed databases with the aim of collating evidence on the intakes of all types of dairy and their effects on the gut microbiota in adults. Risk of bias was assessed using the Cochrane risk-of-bias tool.The search resulted in 6,592 studies, of which eight randomized controlled trials (RCTs) met pre-determined eligibility criteria for inclusion, consisting of a total of 468 participants. Seven studies assessed the effect of type of dairy (milk, yogurt, and kefir) and dairy derivatives (whey and casein) on the gut microbiota, and one study assessed the effect of the quantity of dairy (high dairy vs low dairy). Three studies showed that dairy types consumed (milk, yogurt, and kefir) increased the abundance of beneficial genera Lactobacillus and Bifidobacterium. One study showed that yogurt reduced the abundance of Bacteroides fragilis, a pathogenic strain. Whey and casein isolates and the quantity of dairy consumed did not prompt changes to the gut microbiota composition. All but one study reported no changes to bacterial diversity in response to dairy interventions and one study reported reduction in bacterial diversity in response to milk intake.In conclusion, the results of this review suggest that dairy products such as milk, yogurt, and kefir may modulate the gut microbiota composition in favor to the host. However, the broader health implications of these findings remain unclear and warrant further studies.

Efficacy and safety of fecal microbiota transplantation for the treatment of diseases other than Clostridium difficile infection: a systematic review and meta-analysis

The intestinal microbiome has been identified as a key modifier for a variety of health conditions. Fecal Microbiota Transplantation (FMT) has emerged as a fast, safe, and effective means by which to modify the intestinal microbiome and potentially treat a variety of health conditions. Despite extensive research of FMT for CDI, there is a lack of clarity informed by systematic synthesis of data regarding the safety and efficacy of FMT for other health conditions. This systematic review used PRISMA guidelines and was prospectively registered with PROSPERO (CRD42018104243). In March 2020, a search of MEDLINE, EMBASE, and PsycINFO was conducted. We identified 26 eligible studies. A meta-analysis of FMT for active Ulcerative Colitis (UC) showed that FMT significantly improved rates of clinical remission (OR = 3.634, 95% CI = 1.940 to 6.808, I² = 0%, p < .001), clinical response (OR = 2.634, 95% CI = 1.441 to 4.815, I² = 33%, p = .002) and endoscopic remission (OR = 4.431, 95% CI = 1.901 to 10.324, I² = 0%, p = .001). With respect to Irritable Bowel Syndrome, a meta-analysis showed no significant change in symptoms following FMT (p = .739). Hepatic disorders, metabolic syndrome, and antibiotic-resistant organisms were conditions with emerging data on FMT. Serious adverse events (AE) were more often reported in control group participants (n = 43) compared with FMT group participants (n = 26). There were similar rates of mild to moderate AE in both groups. Preliminary data suggest that FMT is a potentially safe, well-tolerated and efficacious treatment for certain conditions other than CDI, with evidence for active UC being the most compelling.

Obesity, Akkermansia muciniphila, and Proton Pump Inhibitors: Is there a Link?

OBJECTIVE

The gut bacterium Akkermansia muciniphila (A. muciniphila), has been linked to body composition and metabolism. However, the role of lifestyle factors and medication use in these relationships has not been considered. This study aimed to assess the relative abundance of A. muciniphila in participants and investigate its association with obesity, with consideration of potential confounding factors.

METHODS

Participants included 158 men of the Geelong Osteoporosis Study with dual-energy X-ray absorptiometry data, 16S rRNA gene bacterial profiling of stool samples, and lifestyle data. The relative abundance of A. muciniphila was estimated from total sequence reads, while obesity status was quantified by fat mass index (FMI, kg/m²).

RESULTS

In this cohort (66 ± 12 yr, mean ± SD), the most common medications were proton pump inhibitors (PPIs) (28%), and these were associated with both high FMI and decreased abundance of A. muciniphila. Before and after adjustments for PPIs, participants with substantial A. muciniphila (abundance ≥0.1%, n = 94) compared to very low (abundance <0.1%, n = 64), had lower FMI (adjusted -1.33 (95%CI -2.30, -0.36) kg/m², p = 0.007).

CONCLUSIONS

In this sample, relative abundance of A. muciniphila was inversely associated with high FMI, independent of PPI use. The relationship between obesity, reflux medication, and the gut microbiome warrants further investigation.

The effect of blueberry interventions on cognitive performance and mood: A systematic review of randomized controlled trials

Blueberries are rich in polyphenols that may be beneficial to cognitive performance and mood. The aim of this systematic review was to evaluate randomized controlled trials investigating the effects of blueberries and blueberry products on measures of cognition and mood. In total, eleven articles (that included 12 studies) were identified using freeze-dried blueberries (n = 9 studies), whole blueberries (n = 2) and blueberry concentrate (n = 1). These studies were conducted in children (n = 5), young adults (n = 1), and older people with either no known cognitive impairment (n = 4) or indicated cognitive impairment (n = 2). Eight studies reported blueberry consumption or supplementation at various doses and time lengths to improve measures of cognitive performance, particularly short- and long-term memory and spatial memory. For mood, one study reported significant between-group improvements in positive affect from blueberry products, whereas four studies reported no improvement. Low risk of bias were observed across all studies. Based on the current evidence, blueberries may improve some measures of cognitive performance. However, considerable differences in study design, dosages, and anthocyanin content hinder between-study comparison. The use of standardized blueberry interventions, consideration of placebo formulations, and consistently reported cognitive performance tools are recommended in future trials. PROSPERO registration no. CRD42018100888.

Gut microbiota composition during infancy and subsequent behavioural outcomes

Background

Despite intense interest in the relationship between gut microbiota and brain development, longitudinal data from human studies are lacking. This study aimed to investigate the relationship between the composition of gut microbiota during infancy and subsequent behavioural outcomes.

Methods

A subcohort of 201 children with behavioural outcome measures was identified within a longitudinal, Australian birth-cohort study. The faecal microbiota were analysed at 1, 6, and 12 months of age. Behavioural outcomes were measured at 2 years of age.

Findings

In an unselected birth cohort, we found a clear association between decreased normalised abundance of Prevotella in faecal samples collected at 12 months of age and increased behavioural problems at 2 years, in particular Internalizing Problem scores. This association appeared independent of multiple potentially confounding variables, including maternal mental health. Recent exposure to antibiotics was the best predictor of decreased Prevotella.

Interpretation

Our findings demonstrate a strong association between the composition of the gut microbiota in infancy and subsequent behavioural outcomes; and support the importance of responsible use of antibiotics during early life.

Funding

This study was funded by the National Health and Medical Research Council of Australia (1082307, 1147980, 1129813), The Murdoch Children's Research Institute, Barwon Health, Deakin University, Perpetual Trustees, and The Shepherd Foundation. The funders had no involvement in the data collection, analysis or interpretation, trial design, recruitment or any other aspect pertinent to the study.

Gut microbiota differences between healthy older adults and individuals with Parkinson's disease: A systematic review

The 'Dual Hit' hypothesis, stating that Parkinson's disease (PD) begins via olfactory pathways and the gut, and the gastrointestinal symptoms PD individuals face, have largely driven the interest of the gut's involvement in PD. Studies have since observed gut microbiota differences between PD groups and controls, with these alterations potentially relating to PD pathophysiology. However, differences in the studies' methodologies precludes unanimity on the relationships of gut microbiota to PD. Thirteen observational case-control studies investigating gut microbiota in PD and controls were reviewed to assess how microbiota abundance and diversity relates to PD. Nine studies showed butyrate producing gut microbiota had lower abundances in PD compared to controls. Three studies reported α-diversity was higher, with one reporting it was lower, in PD compared to controls. Given most studies show abundance, not diversity, differences of butyrate producing bacteria between groups, we propose abundance differences are more associated with PD than microbiota diversity. As current research is observational, investigating how specific bacteria and their metabolites may alter throughout PD progression is warranted.

Effect of saffron supplementation on symptoms of depression and anxiety: a systematic review and meta-analysis

CONTEXT

Saffron (Crocus sativus L.) has gained interest as a potential treatment in psychiatry.

OBJECTIVE

This systematic review and meta-analysis sought to investigate the effect of saffron supplementation, as both an adjunctive therapy and monotherapy, on symptoms of depression and anxiety in clinical and general populations compared with pharmacotherapy or placebo.

DATA SOURCES

Using the PRISMA guidelines, a systematic literature review of randomized controlled trials was conducted.

DATA EXTRACTION

A meta-analysis was conducted to determine treatment effect. Risk of bias was assessed using the Jadad scale.

RESULTS

Twenty-three studies were included. Saffron had a large positive effect size when compared with placebo for depressive symptoms (g = 0.99, P < 0.001) and anxiety symptoms (g = 0.95, P < 0.006). Saffron also had a large positive effect size when used as an adjunct to antidepressants for depressive symptoms (g = 1.23, P = 0.028). Egger's regression test found evidence of publication bias.

CONCLUSIONS

Saffron could be an effective intervention for symptoms of depression and anxiety; however, due to evidence of publication bias and lack of regional diversity, further trials are required. PROSPERO registration CRD42017070060.

Nutrition-related interventions targeting childhood overweight and obesity: A narrative review

Systematic reviews of nutritional interventions indicate limited efficacy in reducing childhood obesity, but their blanket conclusions could obscure promising components. This narrative review sought more detail on effective components within nutrition-related interventions involving children aged 2 to 11 years. In May 2016, the World Health Organization (WHO) searched the Cochrane Library and PubMed for relevant reviews. From 36 reviews, we screened 182 nutrition-related randomized trials for inclusion. We then reviewed those that reported at least 1 statistically significant (P < 0.05) treatment benefit on body weight and/or composition outcomes at their longest follow-up assessment. Fourteen trials met inclusion criteria (median n = 554; mean intervention duration = 10.8 mo; follow-up = 4.4 mo). "Effective" approaches included environmental changes such as school water fountain installations and cafeteria menu changes and possibly less sustainable strategies such as health education lessons. However, effect sizes even of these selected significant treatment benefits were modest-significant body mass index z-score effects range from -0.1 to -0.2. Each trial was associated with very small improvements in body composition. Because this is a "best-case" scenario (reflecting our design), trialists should rigorously test these strategies alone and possibly together; be open to novel strategies; and ensure that each strategy is culturally relevant and self-sustainable.

Unravelled facets of milk derived opioid peptides: a focus on gut physiology, fractures and obesity

Beyond being a source of key nutrients, bovine milk influences physiological functions by synthesising bioactive peptides during the process of digestion. Some of the claimed negative health outcomes associated with milk consumption, such as cardiovascular diseases and type 1 diabetes may be attributed to an opioid peptide, beta-casomorphin-7 (BCM-7), derived from A1 beta-casein. BCM-7 exerts its function by binding to the μ-opioid receptors in the body. It is hypothesised that activation of the μ-opioid receptors in the gut can alter gut microbial composition, impair gut barrier integrity and bile acid metabolism, in addition to increasing gastrointestinal transit time and gut inflammation. Further, it is hypothesised that BCM-7 may influence fractures and obesity via μ-opioid receptor pathways. In conclusion, it appears that BCM-7 might have multiple functions pertinent to human health; however, the evidence is limited and warrants further pre-clinical and clinical studies for hypothesis confirmation.

Neuroscientific explanations and the stigma of mental disorder: a meta-analytic study

Genetic and other biological explanations appear to have mixed blessings for the stigma of mental disorder. Meta-analytic evidence shows that these “biogenetic” explanations reduce the blame attached to sufferers, but they also increase aversion, perceptions of dangerousness, and pessimism about recovery. These relationships may arise because biogenetic explanations recruit essentialist intuitions, which have known associations with prejudice and the endorsement of stereotypes. However, the adverse implications of biogenetic explanations as a set may not hold true for the subset of those explanations that invoke neurobiological causes. Neurobiological explanations might have less adverse implications for stigma than genetic explanations, for example, because they are arguably less essentialist. Although this possibility is important for evaluating the social implications of neuroscientific explanations of mental health problems, it has yet to be tested meta-analytically. We present meta-analyses of links between neurobiological explanations and multiple dimensions of stigma in 26 correlational and experimental studies. In correlational studies, neurobiological explanations were marginally associated with greater desire for social distance from people with mental health problems. In experimental studies, these explanations were associated with greater desire for social distance, greater perceived dangerousness, and greater prognostic pessimism. Neurobiological explanations were not linked to reduced blame in either set of studies. By implication, neurobiological explanations have the same adverse links to stigma as other forms of biogenetic explanation. These findings raise troubling implications about the public impact of psychiatric neuroscience research findings. Although such findings are not intrinsically stigmatizing, they may become so when viewed through the lens of neuroessentialism.

Do Fathers' Home Reading Practices at Age 2 Predict Child Language and Literacy at Age 4?

BACKGROUND

Maternal shared reading practices predict emergent literacy, but fathers' contributions are less certain. We examined whether fathers' shared home reading activities at 2 years predict language and emergent literacy at age 4 years, when controlling for maternal contributions; and whether this differentially benefits these outcomes in disadvantaged children.

METHODS

Two-parent families were recruited from 5 relatively disadvantaged communities for the universal Let's Read literacy promotion population-based trial (ISRCTN 04602902) in Melbourne, Australia. For exposure at 2 years, home reading practices were recorded via self-reported maternal and paternal StimQ-Toddler questionnaires and dichotomized at study median (high vs low). At 4 years, outcomes assessed included receptive and expressive language (Clinical Evaluation of Language Fundamentals 4) and emergent literacy (Sunderland Phonological Awareness Test-Revised). Linear regression, adjusted for mothers' home reading, was performed to assess 2-year-old vocabulary and communication skills and family disadvantage. Interaction of disadvantage (yes vs no) with high home reading by fathers and at least one parent was assessed.

RESULTS

Data were available for 405 families (64.3%). High father reading at 2 years (reference: low) predicted better expressive (mean difference, 4.7; 95% confidence interval, 1.5 to 8.0) and receptive (mean difference, 5.0; 95% confidence interval, 1.8 to 8.2) language at 4 years (both P < .001), but not emergent literacy skills. Similar patterns were observed in families with at least one parent with high home reading. Fathers' reading did not differentially benefit outcomes in disadvantaged children.

CONCLUSIONS

Fathers' involvement in reading at 2 years predicted better language but not emergent literacy at 4 years, and it did not protect against adverse effects of socioeconomic disadvantage.

Self and informant report ratings of psychopathology in genetic generalized epilepsy

The psychological sequelae of genetic generalized epilepsies (GGE) is of growing research interest, with up to a third of all adults with GGE experiencing significant psychiatric comorbidity according to a recent systematic review. A number of unexplored questions remain. Firstly, there is insufficient evidence to determine relative prevalence of psychopathology between GGE syndromes. Secondly, the degree to which self-report and informant-report questionnaires accord in adults with epilepsy is unknown. Finally, while epilepsy severity is one likely predictor of worse psychopathology in GGE, evidence regarding other possible contributing factors such as epilepsy duration and antiepileptic drugs (AEDs) has been equivocal. The potential impact of subclinical epileptiform discharges remains unexplored. Self-report psychopathology symptoms across six DSM-Oriented Subscales were prospectively measured in 60 adults with GGE, with informant-report provided for a subset of 47. We assessed the burden of symptoms from both self- and informant-report, and the relationship between clinical epilepsy variables and self-reported symptoms. Results showed elevated symptoms in almost half of the sample overall. Depression and anxiety were the most commonly reported types of symptoms. There was a trend towards greater symptoms endorsement by self-report, and relatively modest interrater agreement. Symptoms of ADHD were significantly positively associated with number of AEDs currently prescribed. Other psychopathology symptoms were not significantly predicted by epilepsy duration, seizure-free duration or total duration of epileptiform discharges over a 24-hour period. The high prevalence of psychological needs suggests that routine screening of psychopathology and provision of psychoeducation may be essential to improving patient care and outcomes. Further investigation is required to better understand predictive and causal factors for psychopathology in GGE.