Gut microbiome in ADHD and its relation to neural reward anticipation

Potential application of helminth therapy for resolution of neuroinflammation in neuropsychiatric disorders

Neuropsychiatric disorders (NPDs) are among the major debilitating disorders worldwide with multiple etiological factors. However, in recent years, psychoneuroimmunology uncovered the role of inflammatory condition and autoimmune disorders in the etiopathogenesis of different NPDs. Hence, resolution of inflammation is a new therapeutic target of NPDs. On the other hand, Helminth infections are among the most prevalent infectious diseases in underdeveloped countries, which usually caused chronic infections with minor clinical symptoms. Remarkably, helminths are among the master regulator of inflammatory reactions and epidemiological studies have shown an inverse association between prevalence of autoimmune disorders with these infections. As such, changes of intestinal microbiota are known to be associated with inflammatory conditions in various NPDs. Conversely, helminth colonization alters the intestinal microbiota composition that leads to suppression of intestinal inflammation. In animal models and human studies, helminths or their antigens have shown to be protected against severe autoimmune and allergic disorders, decline the intensity of inflammatory reactions and improved clinical symptoms of the patients. Therefore, "helminthic therapy" have been used for modulation of immune disturbances in different autoimmunity illnesses, such as Multiple Sclerosis (MS) and Inflammatory Bowel Disease (IBD). Here, it is proposed that "helminthic therapy" is able to ameliorate neuroinflammation of NPDs through immunomodulation of inflammatory reactions and alteration of microbiota composition. This review discusses the potential application of "helminthic therapy" for resolution of neuroinflammation in NPDs.

The role of gut microbiota in the pathogenesis of neuropsychiatric and neurodegenerative diseases

According to current knowledge, the number of microorganisms living in our body slightly exceeds the number of our own cells, and most of them occupy the large intestine. New methods for analyzing microorganisms residing in our intestine (intestinal microbiota) enable a better understanding of their metabolic, protective and structural functions as well as complex interactions with the host. The development of microbiota is dynamic, and its composition may change during our lifetime. Many factors can affect the composition of microbiota, such as diet, stress, age, genetic factors and antibiotic therapy. Microbiota-gut-brain communication is bi-directional and is mediated via neuronal, immunological and humoral pathways. This article focuses on gut-brain axis elements, such as the vagus nerve, hypothalamic-pituitary-adrenal axis (HPA), cytokines, neurotransmitters, hormones and intestinal peptides, allowing microbiota to contact with the central nervous system. Moreover, this article shows the mechanisms by which microbiota affects the brain functions related to our behavior, mood and cognitive processes. In addition, the role of microbiota composition disorders in the pathogenesis of central nervous system diseases (such as depression, autism spectrum disorder, schizophrenia, multiple sclerosis, Parkinson’s disease and Alzheimer’s disease) is discussed. This article also focuses on the results from studies in which probiotics have been used as potential therapeutic agents in the treatment of gastrointestinal disorders and also alleviating the symptoms of the central nervous system diseases.

Early life home microbiome and hyperactivity/inattention in school-age children

This study evaluates the association between indoor microbial diversity early in life and hyperactivity/inattention symptoms in children at ages 10 and 15 years.A random sample enriched with subjects with hyperactivity/inattention at age 15 years was selected from the German LISA birth cohort. Bedroom floor dust was collected at age 3 months and 4 bacterial and fungal diversity measures [number of observed operational taxonomic units (OTUs), Chao1, Shannon and Simpson indices] were calculated from Illumina MiSeq sequencing data. Hyperactivity/inattention was based on the Strengths and Difficulties Questionnaire at ages 10 and 15 (cut-off ≥7). Adjusted associations between 4 diversity measures in tertiles and hyperactivity/inattention were investigated with weighted and survey logistic regression models. We included 226 individuals with information on microbial diversity and hyperactivity/inattention. Early life bacterial diversity was inversely associated with hyperactivity/inattention at age 10 [bacterial OTUs (medium vs low: aOR = 0.4, 95%CI = (0.2–0.8)) and Chao1 (medium vs low: 0.3 (0.1–0.5); high vs low: 0.3 (0.2–0.6)], whereas fungal diversity was directly associated [Chao1 (high vs low: 2.1 (1.1–4.0)), Shannon (medium vs low: 2.8 (1.3–5.8)), and Simpson (medium vs low: 4.7 (2.4–9.3))]. At age 15, only Shannon index was significantly associated with hyperactivity/inattention [bacteria (medium vs low: 2.3 (1.2–4.2); fungi (high vs low: 0.5 (0.3–0.9))]. In conclusion, early life exposure to microbial diversity may play a role in the psychobehavioural development. We observe heterogeneity in the direction of the associations encouraging further longitudinal studies to deepen our understanding of the characteristics of the microbial community underlying the observed associations.

The Potential Influence of the Bacterial Microbiome on the Development and Progression of ADHD

The latest research cumulates staggering information about the correlation between the microbiota-gut-brain axis and neurodevelopmental disorders. This review aims to shed light on the potential influence of the microbiome on the development of the most prevalent neurodevelopmental disease, attention-deficit-hyperactive disorder (ADHD). As the etiology and pathophysiology of ADHD are still unclear, finding viable biomarkers and effective treatment still represent a challenge. Therefore, we focused on factors that have been associated with a higher risk of developing ADHD, while simultaneously influencing the microbial composition. We reviewed the effect of a differing microbial makeup on neurotransmitter concentrations important in the pathophysiology of ADHD. Additionally, we deduced factors that correlate with a high prevalence of ADHD, while simultaneously affecting the gut microbiome, such as emergency c-sections, and premature birth as the former leads to a decrease of the gut microbial diversity and the latter causes neuroprotective Lactobacillus levels to be reduced. Also, we assessed nutritional influences, such as breastfeeding, ingestion of short-chain fatty acids (SCFAs) and polyunsaturated fatty acids (PUFAs) on the host′s microbiome and development of ADHD. Finally, we discussed the potential significance of Bifidobacterium as a biomarker for ADHD, the importance of preventing premature birth as prophylaxis and nutrition as a prospective therapeutic measurement against ADHD.

Biomarker Research in ADHD: the Impact of Nutrition (BRAIN) - study protocol of an open-label trial to investigate the mechanisms underlying the effects of a few-foods diet on ADHD symptoms in children

INTRODUCTION

Attention deficit hyperactivity disorder (ADHD) is the most common childhood behavioural disorder, causing significant impediment to a child's development. It is a complex disorder with numerous contributing (epi)genetic and environmental factors. Currently, treatment consists of behavioural and pharmacological therapy. However, ADHD medication is associated with several side effects, and concerns about long-term effects and efficacy exist. Therefore, there is considerable interest in the development of alternative treatment options. Double-blind research investigating the effects of a few-foods diet (FFD) has demonstrated a significant decrease in ADHD symptoms following an FFD. However, an FFD requires a considerable effort of both child and parents, limiting its applicability as a general ADHD treatment. To make FFD intervention less challenging or potentially obsolete, we need to understand how, and in which children, an FFD affects ADHD behaviour and, consequently, the child's well-being. We hypothesise that an FFD affects brain function, and that the nutritional impact on ADHD is effectuated by a complex interplay between the microbiota, gut and brain, that is, the microbiota-gut-brain axis.

METHODS AND ANALYSIS

The Biomarker Research in ADHD: the Impact of Nutrition (BRAIN) study is an open-label trial with researchers blinded to changes in ADHD symptoms during sample processing and initial data analyses.

ETHICS AND DISSEMINATION

The Medical Research and Ethics Committee of Wageningen University has approved this study (NL63851.081.17, application 17/24). Results will be disseminated through peer-reviewed journal publications, conference presentations, (social) media and the BRAIN study website. A summary of the findings will be provided to the participants.

TRIAL REGISTRATION NUMBER

NCT03440346.

STUDY DATES

Collection of primary outcome data started in March 2018 and will be ongoing until 100 children have participated in the study. Sample data analysis will start after all samples have been collected.

Antibiotic Exposure in the First Year of Life and the Risk of Attention-Deficit/Hyperactivity Disorder: A Population-Based Cohort Study

Early childhood antibiotic exposure induces changes in gut microbiota reportedly associated with the development of attention-deficit/hyperactivity disorder (ADHD). We conducted a population-based cohort study to examine the association between antibiotic use in the first year of life and ADHD risk. We included children born in Manitoba, Canada, between 1998 and 2017. Exposure was defined as having filled 1 or more antibiotic prescriptions during the first year of life. ADHD diagnosis was identified in hospital abstracts, physician visits, or drug dispensations. Risk of developing ADHD was estimated using Cox proportional hazards regression in a high-dimensional propensity score-matched cohort (n = 69,738) and a sibling cohort (n = 67,671). ADHD risk was not associated with antibiotic exposure in the matched-cohort (hazard ratio = 1.02, 95% confidence interval: 0.97, 1.08) or in the sibling cohort (hazard ratio = 0.96, 95% confidence interval: 0.89, 1.03). In secondary analyses of the matched cohort, ADHD risk increase was observed in those exposed to 4 or more antibiotic courses or a duration longer than 3 weeks. These associations were not observed in the sibling cohort. We concluded that antibiotic exposure in the first year of life does not pose an ADHD risk on a population level.

The gut microbiome in psychiatry: A primer for clinicians

Research in the past decade has shown that variations in the gut microbiome may influence behavior, and vice versa. As such, interest in the role of the gut microbiome in psychiatric conditions has drawn immense interest. This is evidenced by the recent surge in published studies examining microbial dysbiosis in clinical psychiatric populations, particularly autism spectrum disorder and depression. However, critical examination of these studies reveals methodological flaws in design and execution, suggesting that they may not be held to the same standards as other bodies of clinical research. Given the complex nature of the gut microbiome, this narrative review attempts to clarify concepts critical to effectively examine its potential role in psychopathology to appropriately inform mental health researchers. More specifically, the numerous variables known to affect the gut microbiome are discussed, including inflammation, diet, weight, and medications. A comprehensive review of the extant microbiome literature in clinical psychiatric populations is also provided, in addition to clinical implications and suggestions for future directions of research. Although there is a clear need for additional studies to elucidate the gut microbiome's role in psychiatric disorders, there is an even greater need for well-designed, appropriately controlled studies to truly impact the field.

Prenatal pet keeping and caregiver-reported attention deficit hyperactivity disorder through preadolescence in a United States birth cohort

BACKGROUND

While the keeping of pets has been shown to protect against childhood allergic disease and obesity, less is known regarding potential associations of prenatal pet keeping and attention deficit hyperactivity disorder (ADHD). We sought to examine the associations between prenatal dog or cat keeping with caregiver-reported ADHD in preadolescents in the Wayne County Health, Environment, Allergy and Asthma Longitudinal Study (WHEALS) birth cohort (N = 1258).

METHODS

At an interview with the caregiver at child age 10-12 years, caregivers reported if the WHEALS child had ever been diagnosed with ADHD. Similarly, during an interview with the mother prenatally, pet keeping (defined as dog or cat kept inside ≥1 h/day) was ascertained. Logistic regression models were fit to examine the association of prenatal pet keeping (dog keeping and cat keeping, separately) with ADHD.

RESULTS

A subset of 627 children were included in the analyses: 93 who had ADHD and 534 with neurotypical development. After accounting for confounders and loss to follow-up, maternal prenatal dog exposure was associated with 2.23 times (95% CI: 1.15, 4.31; p = 0.017) greater odds of ADHD among boys. Prenatal dog keeping was not statistically significantly associated with ADHD in girls (odds ratio = 0.27, 95% CI: 0.06, 1.12; p = 0.070). Prenatal cat keeping was not associated with ADHD.

CONCLUSIONS

In boys, but not girls, maternal prenatal dog keeping was positively associated with ADHD. Further study to confirm these findings and to identify potential mechanisms of this association (e.g., modification of the gut microbiome, exposure to environmental toxicants or pet-related medications) is needed.

Rationale and design of an international randomized placebo-controlled trial of a 36-ingredient micronutrient supplement for children with ADHD and irritable mood: The Micronutrients for ADHD in Youth (MADDY) study

Background

Attention-Deficit/Hyperactivity Disorder (ADHD) is a chronic neurodevelopmental disorder affecting up to 9% of children and substantial numbers of adults. Existing pharmacologic treatments often improve symptoms, but concerns exist over side effects, stigma, potential long-term health effects, and residual irritability, often treated with adjunctive antipsychotics. To address public and clinician demand for non-pharmacologic evidence-based treatments, this study will examine efficacy of a 36-ingredient micronutrient (vitamin/mineral) supplement as treatment for children with ADHD and irritability.

Methods

An international team of experts in ADHD, mood dysregulation, nutrition, epidemiology, and clinical trials conferred to develop/refine a protocol powered to detect a medium effect. The study will employ a fully-blind randomized controlled trial (RCT) design, comparing the micronutrient supplement to matched placebo in 135 children aged 6-12 with ADHD symptoms and irritability, based on the parent-rated Child and Adolescent Symptom Inventory-5 (CASI-5). Irritability will be measured by at least one symptom of oppositional defiant disorder (ODD) or disruptive mood dysregulation disorder (DMDD). Based on research suggesting an irritable ADHD subtype, the primary outcome will be a composite score comprised of the CASI-5 subscales: ADHD, ODD, DMDD, and the Peer Conflict Scale, which assesses anger and aggression perpetrated towards peers. Participants will provide biological samples (blood, urine, saliva, hair and stool) to explore the micronutrients' mechanisms of action.

Discussion

This study is the first adequately powered RCT in North America to examine both behavioral responses to, and biological mechanisms of, micronutrients for ADHD and irritability in children. If found efficacious, broad-spectrum micronutrients, given at therapeutic doses, may provide an evidence-based alternative to prescription medications for ADHD and associated irritability.

Trial registration

NCT03252522. Registered 26 July 2017.

The Microbiota-Gut-Brain Axis

The importance of the gut-brain axis in maintaining homeostasis has long been appreciated. However, the past 15 yr have seen the emergence of the microbiota (the trillions of microorganisms within and on our bodies) as one of the key regulators of gut-brain function and has led to the appreciation of the importance of a distinct microbiota-gut-brain axis. This axis is gaining ever more traction in fields investigating the biological and physiological basis of psychiatric, neurodevelopmental, age-related, and neurodegenerative disorders. The microbiota and the brain communicate with each other via various routes including the immune system, tryptophan metabolism, the vagus nerve and the enteric nervous system, involving microbial metabolites such as short-chain fatty acids, branched chain amino acids, and peptidoglycans. Many factors can influence microbiota composition in early life, including infection, mode of birth delivery, use of antibiotic medications, the nature of nutritional provision, environmental stressors, and host genetics. At the other extreme of life, microbial diversity diminishes with aging. Stress, in particular, can significantly impact the microbiota-gut-brain axis at all stages of life. Much recent work has implicated the gut microbiota in many conditions including autism, anxiety, obesity, schizophrenia, Parkinson’s disease, and Alzheimer’s disease. Animal models have been paramount in linking the regulation of fundamental neural processes, such as neurogenesis and myelination, to microbiome activation of microglia. Moreover, translational human studies are ongoing and will greatly enhance the field. Future studies will focus on understanding the mechanisms underlying the microbiota-gut-brain axis and attempt to elucidate microbial-based intervention and therapeutic strategies for neuropsychiatric disorders.

Early nutrition and gut microbiome: interrelationship between bacterial metabolism, immune system, brain structure, and neurodevelopment

Disturbances of diet during pregnancy and early postnatal life may impact colonization of gut microbiota during early life, which could influence infant health, leading to potential long-lasting consequences later in life. This is a nonsystematic review that explores the recent scientific literature to provide a general perspective of this broad topic. Several studies have shown that gut microbiota composition is related to changes in metabolism, energy balance, and immune system disturbances through interaction between microbiota metabolites and host receptors by the gut-brain axis. Moreover, recent clinical studies suggest that an intestinal dysbiosis in gut microbiota may result in cognitive disorders and behavioral problems. Furthermore, recent research in the field of brain imaging focused on the study of the relationship between gut microbial ecology and large-scale brain networks, which will help to decipher the influence of the microbiome on brain function and potentially will serve to identify multiple mediators of the gut-brain axis. Thus, knowledge about optimal nutrition by modulating gut microbiota-brain axis activity will allow a better understanding of the molecular mechanisms involved in the crosstalk between gut microbiota and the developing brain during critical windows. In addition, this knowledge will open new avenues for developing novel microbiota-modulating based diet interventions during pregnancy and early life to prevent metabolic disorders, as well as neurodevelopmental deficits and brain functional disorders.

The Role of the Gut-Brain Axis in Attention-Deficit/Hyperactivity Disorder

Genetic and environmental factors play a role in the cause and development of attention-deficit/hyperactivity disorder (ADHD). Recent studies have suggested an important role of the gut-brain axis (GBA) and intestinal microbiota in modulating the risk of ADHD. Here, the authors provide a brief overview of the clinical and biological picture of ADHD and how the GBA could be involved in its cause. They discuss key biological mechanisms involved in the GBA and how these may increase the risk of developing ADHD. Understanding these mechanisms may help to characterize novel treatment options via identification of disease biomarkers.

Gut microbiome: An intermediary to neurotoxicity

There is growing recognition that the gut microbiome is an important regulator for neurological functions. This review provides a summary on the role of gut microbiota in various neurological disorders including neurotoxicity induced by environmental stressors such as drugs, environmental contaminants, and dietary factors. We propose that the gut microbiome remotely senses and regulates CNS signaling through the following mechanisms: 1) intestinal bacteria-mediated biotransformation of neurotoxicants that alters the neuro-reactivity of the parent compounds; 2) altered production of neuro-reactive microbial metabolites following exposure to certain environmental stressors; 3) bi-directional communication within the gut-brain axis to alter the intestinal barrier integrity; and 4) regulation of mucosal immune function. Distinct microbial metabolites may enter systemic circulation and epigenetically reprogram the expression of host genes in the CNS, regulating neuroinflammation, cell survival, or cell death. We will also review the current tools for the study of the gut-brain axis and provide some suggestions to move this field forward in the future.

Gut microbiota composition is associated with temperament traits in infants

BACKGROUND

One of the key behavioral phenotypes in infancy are different temperament traits, and certain early life temperament traits have been shown to precede later mental health problems. Differences in the gut microbiota composition (GMC) have been suggested to link with neurodevelopment. For example, toddler temperament traits have been found to associate with differences in GMC; however, studies in infants are lacking although infancy is a rapid period of neurodevelopment as well as GM development. Thus, we aimed to investigate association between infant GMC and temperament.

METHODS

The study population (n = 301, 53% boys) was drawn from the FinnBrain Birth Cohort Study. Stool samples were collected from the 2.5-month-old infants and sequenced with 16S Illumina MiSeq platform. GMC taxonomic composition (at Genus and OTU level), observed sample clusters, diversity and richness were investigated in relation to the maternal reports of Infant Behavior Questionnaire -Revised (IBQ-R) at the age of 6 months.

RESULTS

Three sample clusters (Bifidobacterium/Enterobacteriaceae, Bacteroides, V. Dispar) based on GMC were identified, of which Bifidobacterium/Enterobacteriaceae-cluster presented with higher scores on the IBQ-R main dimension regulation and its subscale duration of orienting compared to Bacteroides-cluster. The clusters associated with temperament in a sex-dependent manner. The IBQ-R main dimension surgency (positive emotionality) was associated positively both with genus Bifidobacterium and Streptococcus. Alpha diversity had a negative association with negative emotionality and fear reactivity.

CONCLUSION

This is the first study demonstrating associations, but not causal connections, between GMC and temperament in young infants in a prospective design.

A Systematic Review of the Microbiome in Children With Neurodevelopmental Disorders

Background and Purpose: A relationship between gut microbiome and central nervous system (CNS), have been suggested. The human microbiome may have an influence on brain's development, thus implying that dysbiosis may contribute in the etiology and progression of some neurological/neuropsychiatric disorders. The objective of this systematic review was to identify evidence on the characterization and potential distinctive traits of the microbiome of children with neurodevelopmental disorders, as compared to healthy children. Methods: The review was performed following the methodology described in the Cochrane handbook for systematic reviews, and was reported based on the PRISMA statement for reporting systematic reviews and meta-analyses. All literature published up to April 2019 was retrieved searching the databases PubMed, ISI Web of Science and the Cochrane Database of Systematic Reviews. Only observational studies, published in English and reporting data on the characterization of the microbiome in humans aged 0-18 years with a neurodevelopmental disorder were included. Neurodevelopmental disorders were categorized according to the definition included in the Diagnostic and Statistical Manual of Mental Disorders, version 5 (DSM-5). Results: Bibliographic searches yielded 9,237 records. One study was identified through other data sources. A total of 16 studies were selected based on their relevance and pertinence to the topic of the review, and were then applied the predefined inclusion and exclusion criteria. A total of 10 case-control studies met the inclusion criteria, and were thus included in the qualitative analysis and applied the NOS score. Two studies reported data on the gut microbiome of children with ADHD, while 8 reported data on either the gut (n = 6) or the oral microbiome (n = 2) of children with ASD. Conclusions: All the 10 studies included in this review showed a high heterogeneity in terms of sample size, gender, clinical issues, and type of controls. This high heterogeneity, along with the small sample size of the included studies, strongly limited the external validity of results. The quality assessment performed using the NOS score showed an overall low to moderate methodological quality of the included studies. To better clarify the potential role of microbiome in patients with neurodevelopmental disorders, further high-quality observational (specifically cohort) studies are needed.

Increasing reproducibility and interpretability of microbiota-gut-brain studies on human neurocognition and intermediary microbial metabolites

In this commentary, we point to guidelines for performing human neuroimaging studies and their reporting in microbiota-gut-brain (MGB) articles. Moreover, we provide a view on interpretational issues in MGB studies, with a specific focus on gut microbiota–derived metabolites. Thus, extending the target article, we provide recommendations to the field to increase reproducibility and relevance of this type of MGB study.

Human gut microbiome changes during a 10 week Randomised Control Trial for micronutrient supplementation in children with attention deficit hyperactivity disorder

It has been widely hypothesized that both diet and the microbiome play a role in the regulation of attention-deficit/hyperactivity disorder (ADHD) behaviour. However, there has been very limited scientific investigation into the potential biological connection. We performed a 10-week pilot study investigating the effects of a broad spectrum micronutrient administration on faecal microbiome content, using 16S rRNA gene sequencing. The study consisted of 17 children (seven in the placebo and ten in the treatment group) between the ages of seven and 12 years, who were diagnosed with ADHD. We found that micronutrient treatment did not drive large-scale changes in composition or structure of the microbiome. However, observed OTUs significantly increased in the treatment group, and showed no mean change in the placebo group. The differential abundance and relative frequency of Actinobacteria significantly decreased post- micronutrient treatment, and this was largely attributed to species from the genus Bifidobacterium. This was compensated by an increase in the relative frequency of species from the genus Collinsella. Further research is required to establish the role that Bifidobacterium contribute towards neuropsychiatric disorders; however, these findings suggest that micronutrient administration could be used as a safe, therapeutic method to modulate Bifidobacterium abundance, which could have potential implications for modulating and regulating ADHD behaviour. Our pilot study provides an initial observation into this area of research, and highlights an interesting avenue for further investigation in a larger cohort. Furthermore, these novel results provide a basis for future research on the biological connection between ADHD, diet and the microbiome.

Insular resting state functional connectivity is associated with gut microbiota diversity

The gut microbiota has recently gained attention as a possible modulator of brain activity. A number of reports suggest that the microbiota may be associated with neuropsychiatric conditions such as major depressive disorder, autism and anxiety. The gut microbiota is thought to influence the brain via vagus nerve signalling, among other possible mechanisms. The insula processes and integrates these vagal signals. To determine if microbiota diversity and structure modulate brain activity, we collected faecal samples and examined insular function using resting state functional connectivity (RSFC). Thirty healthy participants (non-smokers, tobacco smokers and electronic cigarette users, n = 10 each) were studied. We found that the RSFC between the insula and several regions (frontal pole left, lateral occipital cortex right, lingual gyrus right and cerebellum 4, 5 and vermis 9) were associated with bacterial microbiota diversity and structure. In addition, two specific bacteria genera, Prevotella and Bacteroides, were specifically different in tobacco smokers and also associated with insular connectivity. In conclusion, we show that insular connectivity is associated with microbiome diversity, structure and at least two specific bateria genera. Furthemore, this association is potentially modulated by tobacco smoking, although the sample sizes for the different smoking groups were small and this result needs validation in a larger cohort. While replication is necessary, the microbiota is a readily accessible therapeutic target for modulating insular connectivity, which has previously been shown to be abnormal in anxiety and tobacco use disorders.

Relationship between Antioxidant Status and Attention Deficit Hyperactivity Disorder Among Children

Background:

Attention deficit hyperactivity disorder (ADHD) is one of the prevalent neuropsychiatric disorders in childhood. In general, diagnoses of ADHD include inattention, hyperactivity, and impulsivity. Recent studies have reported increased oxidative stress in psychiatric disorders such as ADHD, but the results are conflicting. This research aimed to study the relationship between antioxidant status and ADHD in children of 6–13 years old.

Methods:

From schools, 32 ADHD students whose diseases were diagnosed by child and adolescence psychiatrist based on Diagnostic and Statistical Manual of Mental Disorders-IV index were recruited; moreover, 32 healthy subjects, which according to the medical history questionnaire of psychiatric disorder had not had chronic disease, were selected. Total antioxidant capacity (TAC), catalase (CAT), glutathione (GSH), and malondiadehyde (MDA) were measured. General information, health history, and medication history were collected. All participants completed a 168-item food frequency questionnaire. Dietary intakes of antioxidants were obtained through this questionnaire.

Results:

There was no significant difference between mean of energy intake and Zn, Se, vitamin E, C, and β-carotene as antioxidants between the two groups. The mean of serum TAC, GSH level, and CAT level in the patients were significantly lower than the healthy group (P < 0.001), but the mean of MDA was not significantly different between the two groups (P = 0.18).

Conclusions:

The result of this study indicates that, in ADHD, the serum levels of GSH, CAT, and TAC decrease; the level of antioxidant in the serum has been compromised to fight oxidative stress. More perspective studies with large sample sizes are essential to confirm these findings.

Stress, depression, diet, and the gut microbiota: human-bacteria interactions at the core of psychoneuroimmunology and nutrition

Humans and their gut bacteria have evolved multiple ways to communicate with and regulate one another. Psychological stress and depression can promote consumption of highly palatable foods, influencing which gut bacteria thrive. Additionally, stress and depression can reshape the gut bacteria's composition through stress hormones, inflammation, and autonomic alterations. In turn, the gut bacteria release metabolites, toxins, and neurohormones that can alter eating behavior and mood. Some bacterial species may encourage dysregulated eating. The gut bacteria may also upregulate stress responsiveness and heighten the risk for depression, which probiotic supplementation may attenuate. This review focuses on human studies to address the bidirectional links among diet, stress, and the gut bacteria, and their impact on immune function and health.

Man and the Microbiome: A New Theory of Everything?

The gut microbiome is implicated in the pathophysiology of a wide range of psychological disorders. Preclinical studies have provided us with key insights into the mechanisms by which the microbiome influences bidirectional gut-brain communication. There are many signaling pathways involved, including the hypothalamic-pituitary-adrenal axis, immune modulation, tryptophan and serotonin metabolism, bile acid transformation, microbial production of neuroactive compounds, and regulation of the endocannabinoid system. The complex and widespread influence of the microbiome on many physiological and psychological processes has generated a keen interest in its therapeutic potential for depression, anxiety, autism, and other psychiatric disorders. It has been shown that the microbiome composition of people suffering with such conditions differs significantly from that of healthy controls, and although the area is in its infancy, interventional studies that alter a person's microbiome through the use of probiotics, prebiotics, or dietary change can alleviate psychopathological symptoms.

Making Sense of … the Microbiome in Psychiatry

Microorganisms can be found almost anywhere, including in and on the human body. The collection of microorganisms associated with a certain location is called a microbiota, with its collective genetic material referred to as the microbiome. The largest population of microorganisms on the human body resides in the gastrointestinal tract; thus, it is not surprising that the most investigated human microbiome is the human gut microbiome. On average, the gut hosts microbes from more than 60 genera and contains more cells than the human body. The human gut microbiome has been shown to influence many aspects of host health, including more recently the brain.Several modes of interaction between the gut and the brain have been discovered, including via the synthesis of metabolites and neurotransmitters, activation of the vagus nerve, and activation of the immune system. A growing body of work is implicating the microbiome in a variety of psychological processes and neuropsychiatric disorders. These include mood and anxiety disorders, neurodevelopmental disorders such as autism spectrum disorder and schizophrenia, and even neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Moreover, it is probable that most psychotropic medications have an impact on the microbiome.Here, an overview will be provided for the bidirectional role of the microbiome in brain health, age-associated cognitive decline, and neurological and psychiatric disorders. Furthermore, a primer on the common microbiological and bioinformatics techniques used to interrogate the microbiome will be provided. This review is meant to equip the reader with a primer to this exciting research area that is permeating all areas of biological psychiatry research.

The Gut-Brain Axis and the Microbiome: Mechanisms and Clinical Implications

BACKGROUND & AIMS

Based largely on results from preclinical studies, the concept of a brain gut microbiome axis has been established, mediating bidirectional communication between the gut, its microbiome, and the nervous system. Limited data obtained in human beings suggest that alterations in these interactions may play a role in several brain gut disorders.

METHODS

We reviewed the preclinical and clinical literature related to the topic of brain gut microbiome interactions.

RESULTS

Well-characterized bidirectional communication channels, involving neural, endocrine, and inflammatory mechanisms, exist between the gut and the brain. Communication through these channels may be modulated by variations in the permeability of the intestinal wall and the blood-brain barrier. Brain gut microbiome interactions are programmed during the first 3 years of life, including the prenatal period, but can be modulated by diet, medications, and stress throughout life. Based on correlational studies, alterations in these interactions have been implicated in the regulation of food intake, obesity, and in irritable bowel syndrome, even though causality remains to be established.

CONCLUSIONS

Targets within the brain gut microbiome axis have the potential to become targets for novel drug development for brain gut disorders.

Stress matters: Randomized controlled trial on the effect of probiotics on neurocognition

Probiotics are microorganisms that provide health benefits when consumed. In animals, probiotics reverse gut microbiome-related alterations in depression-like symptoms, in cognition, and in hormonal stress response. However, in humans, a causal understanding of the gut-brain link in emotion and cognition is lacking. Additionally, whether the effects of probiotics on neurocognition are visible only in presence of stress, remains unclear. We investigated the effects of a multispecies probiotic (Ecologic^®Barrier) on specific neurocognitive measures of emotion reactivity, emotion regulation, and cognitive control using fMRI. Critically, we also tested whether probiotics can buffer against the detrimental effects of acute stress on working memory. In a double blind, randomized, placebo-controlled, between-subjects intervention study, 58 healthy participants were tested once before and once after a 28-day intervention.

Without stress induction, probiotics did not affect brain, behavioral, or related self-report measures. However, relative to placebo, the probiotics group did show a significant stress-related increase in working memory performance after supplementation. This change was associated with intervention-related neural changes in frontal cortex during cognitive control exclusively in the probiotics group. Overall, our results show neurocognitive effects of a multispecies probiotic in healthy women only under challenging situations, buffering against the detrimental effects of stress on cognition.

•

We ran a randomized placebo-controlled fMRI study with a multispecies probiotic.

•

Probiotics did not affect neurocognitive measures of emotion and cognitive control.

•

Probiotics did affect stress-related working memory and neural correlates.

•

Probiotics in healthy individuals can support cognition under stress.

Microbiome-The Missing Link in the Gut-Brain Axis: Focus on Its Role in Gastrointestinal and Mental Health

The central nervous system (CNS) and the human gastrointestinal (GI) tract communicate through the gut-brain axis (GBA). Such communication is bi-directional and involves neuronal, endocrine, and immunological mechanisms. There is mounting data that gut microbiota is the source of a number of neuroactive and immunocompetent substances, which shape the structure and function of brain regions involved in the control of emotions, cognition, and physical activity. Most GI diseases are associated with altered transmission within the GBA that are influenced by both genetic and environmental factors. Current treatment protocols for GI and non-GI disorders may positively or adversely affect the composition of intestinal microbiota with a diverse impact on therapeutic outcome(s). Alterations of gut microbiota have been associated with mood and depressive disorders. Moreover, mental health is frequently affected in GI and non-GI diseases. Deregulation of the GBA may constitute a grip point for the development of diagnostic tools and personalized microbiota-based therapy. For example, next generation sequencing (NGS) offers detailed analysis of microbiome footprints in patients with mental and GI disorders. Elucidating the role of stem cell⁻host microbiome cross talks in tissues in GBA disorders might lead to the development of next generation diagnostics and therapeutics. Psychobiotics are a new class of beneficial bacteria with documented efficacy for the treatment of GBA disorders. Novel therapies interfering with small molecules involved in adult stem cell trafficking are on the horizon.

Connection between gut microbiome and brain development in preterm infants

Dysbiosis of the gut microbiome in preterm infants predisposes the neonate to various major morbidities including neonatal necrotizing enterocolitis and sepsis in the neonatal intensive care unit, and adverse neurological outcomes later in life. There are parallel early developmental windows for the gut microbiota and the nervous system during prenatal to postnatal of life. Therefore, preterm infants represent a unique population in which optimization of initial colonization and microbiota development can affect brain development and enhance neurological outcomes. In this review, we will first discuss the factors affecting the assembly of neonatal gut microbiota and the contribution of dysbiosis in preterm infants to neuroinflammation and neurodevelopmental disorders. We then will discuss the emerging pathways connecting the gut microbiome and brain development. Further we will discuss the significance of current models for alteration of the gut microbiome (including humanized gnotobiotic models and exposure to antibiotics) to brain development and functions. Understanding the role of early optimization of the microbiome in brain development is of paramount importance for developing microbiome-targeted therapies and protecting infants from prematurity-related neurodevelopmental diseases.

Increased zonulin is associated with hyperactivity and social dysfunctions in children with attention deficit hyperactivity disorder

BACKGROUND

In attention deficit hyperactivity disorder (ADHD), deteriorations of brain gut axis has been shown in previous studies. One area where the most important challenges are seen in ADHD is social functioning. Zonulin is a protein found in the intestinal intraepithelial component; it has been shown that the level of zonulin increases when intestinal permeability is impaired. Changes in intestinal function were shown in ADHD. Zonulin has been shown to be associated with social impairment in children with autism spectrum disorder. In this study, it was aimed to evaluate the relationship between the ADHD symptoms and zonulin in children with ADHD. Secondarily relation of zonulin and difficulties in social functioning was examined in these children.

METHODS

Forty children diagnosed with ADHD and forty-one healthy children similar age and gender to ADHD group and their mothers were included in the study. Children without any chronic systemic immunological or infectious diseases were included in the case and control group. The ADHD symptoms were scored by the DuPaul ADHD scale and the social functioning of the children was assessed by the Social Responsiveness Scale (SRS). Serum zonulin levels were analyzed by enzyme-linked immunosorbent assay.

RESULTS

Children with ADHD had higher serum zonulin levels and were more impaired in social functioning compared to controls. The level of zonulin was independently predicted with hyperactivity symptoms and SRS scores in regression analysis.

CONCLUSION

In this sample of children with ADHD, elevated zonulin levels were associated with increased symptoms of hyperactivity and impairment of social functioning.

Gut-Brain Psychology: Rethinking Psychology From the Microbiota-Gut-Brain Axis

Mental disorders and neurological diseases are becoming a rapidly increasing medical burden. Although extensive studies have been conducted, the progress in developing effective therapies for these diseases has still been slow. The current dilemma reminds us that the human being is a superorganism. Only when we take the human self and its partner microbiota into consideration at the same time, can we better understand these diseases. Over the last few centuries, the partner microbiota has experienced tremendous change, much more than human genes, because of the modern transformations in diet, lifestyle, medical care, and so on, parallel to the modern epidemiological transition. Existing research indicates that gut microbiota plays an important role in this transition. According to gut-brain psychology, the gut microbiota is a crucial part of the gut-brain network, and it communicates with the brain via the microbiota-gut-brain axis. The gut microbiota almost develops synchronously with the gut-brain, brain, and mind. The gut microbiota influences various normal mental processes and mental phenomena, and is involved in the pathophysiology of numerous mental and neurological diseases. Targeting the microbiota in therapy for these diseases is a promising approach that is supported by three theories: the gut microbiota hypothesis, the "old friend" hypothesis, and the leaky gut theory. The effects of gut microbiota on the brain and behavior are fulfilled by the microbiota-gut-brain axis, which is mainly composed of the nervous pathway, endocrine pathway, and immune pathway. Undoubtedly, gut-brain psychology will bring great enhancement to psychology, neuroscience, and psychiatry. Various microbiota-improving methods including fecal microbiota transplantation, probiotics, prebiotics, a healthy diet, and healthy lifestyle have shown the capability to promote the function of the gut-brain, microbiota-gut-brain axis, and brain. It will be possible to harness the gut microbiota to improve brain and mental health and prevent and treat related diseases in the future.

Reliability of a participant-friendly fecal collection method for microbiome analyses: a step towards large sample size investigation

Background

The effects of gut microbiota on human traits are expected to be small to moderate and adding the complexity of the human diseases, microbiome research demands big sample sizes. Fecal samples for such studies are mostly self-collected by participants at home. This imposes an extra level of complexity as sample collection and storage can be challenging. Effective, low-burden collection and storage methods allowing fecal samples to be transported properly and ensuring optimal quality and quantity of bacterial DNA for upstream analyses are necessary. Moreover, accurate assessment of the microbiome composition also depends on bacterial DNA extraction method. The aim of this study was to evaluate the reliability and efficiency of the OMNIgene•GUT kit as a participant-fecal friendly collection method (storage at room temperature for 24 h (O24h) or 7 days (O7d)) in comparison to the standard collection method (Fresh, storage at 4 °C for less than 24 h) in terms of amount of variability and information content accounting for two common DNA extraction methods.

Results

Fourteen fecal samples were collected from healthy individuals (7 males, 7 females). Collection and storage methods did not differ significantly in terms of DNA concentration and Shannon diversity index. Phylum relative abundance showed significant differences for Bacteroidetes, Actinobacteria and Cyanobacteria. The differences were observed between control (Fresh) and O24h methods, but not between Fresh and O7d. These differences were not seen when performing bacterial DNA quantification based on three bacterial groups: Bacteroides spp., Bifidobacterium spp. and Clostridium cluster IV, which represent three major phyla: Bacteroidetes, Actinobacteria and Firmicutes respectively. The two DNA extraction methods differ in terms of DNA quantity, quality, bacterial diversity and bacterial relative abundance. Furthermore, principal component analysis revealed differences in microbial structure, which are driven by the DNA extraction methods more than the collection/storage methods.

Conclusion

Our results have highlighted the potential of using the OMNIgene•GUT kit for collection and storage at ambient temperature, which is convenient for studies aiming to collect large samples by giving participants the possibility to send samples by post. Importantly, we revealed that the choice of DNA extraction method have an impact on the microbiome profiling.

Electronic supplementary material

The online version of this article (10.1186/s12866-018-1249-x) contains supplementary material, which is available to authorized users.

Diet Can Impact Microbiota Composition in Children With Autism Spectrum Disorder

Diet is one of the most influential environmental factors in determining the composition of the gastrointestinal microbiota. Microbial dysbiosis in children with Autism Spectrum Disorder (ASD) and the impact of some bacterial taxa on symptoms of ASD has been recognized. Children with ASD are often described as picky eaters with low intake of fiber-rich foods, including fruits and vegetables. However, the impact of diet on the microbiota composition in children with ASD is largely unknown. Herein, fecal samples, 3 day food diaries and the Youth and Adolescence Food Frequency questionnaire (YAQ) were collected from children with ASD (ASD; n = 26) and unaffected controls (CONT; n = 32). Children's ASD symptoms were determined using the Pervasive Developmental Disorder Behavior Inventory Screening Version (PDDBI-SV). Differences in the microbiota composition at the phyla, order, family, and genus level between ASD and CONT were observed. Microbiota composition of children with ASD was investigated in relation to feeding behavior, nutrient and food group intake as well as dietary patterns derived from the YAQ. In children with ASD, two distinct dietary patterns (DP) were associated with unique microbial profiles. DP1, characterized by higher intakes of vegetables, legumes, nuts and seeds, fruit, refined carbohydrates, and starchy vegetables, but lower intakes of sweets, was associated with lower abundance of Enterobacteriaceae, Lactococcus, Roseburia, Leuconostoc, and Ruminococcus. DP2, characterized by low intakes of vegetables, legumes, nuts and seeds and starchy vegetables, was associated with higher Barnesiellaceae and Alistipes and lower Streptophyta, as well as higher levels of propionate, isobutyrate, valerate, and isovalerate. Peptostreptococcaceae and Faecalibacterium predicted social deficit scores in children with ASD as measured by the PDDBI-SV. Diet-associated microbial profiles were related to GI symptoms, but no significant interaction between nutrition and microbiota in predicting social deficit scores were observed. In conclusion, dietary patterns associated with fecal microbiota composition and VFA concentrations in children with ASD were identified. Future studies using a larger sample size and measuring other behaviors associated with ASD are needed to investigate whether dietary intake may be a modifiable moderator of ASD symptoms.

A Gut Feeling: A Hypothesis of the Role of the Microbiome in Attention-Deficit/Hyperactivity Disorders

Attention-deficit/hyperactivity disorder (ADHD) is a neurologic disorder characterized by hyperactivity/impulsivity and/or inattentiveness, with genetic and environmental factors contributing to the disorder. With the growing recognition of the microbiome’s role in many neurological disorders, the authors propose that it may also be implicated in ADHD. Here, we describe several evolving areas of research to support this hypothesis. First, a unique composition of gut bacteria has been identified and linked to behaviors in ADHD. Second, our research found an increased incidence of 2 gastrointestinal symptoms (constipation and flatulence) in children with ADHD, as compared to controls. Finally, emerging data may be interpreted to suggest that immune dysregulation in ADHD be associated with an altered microbiome, low-grade inflammation, and gastrointestinal dysfunction. Although more studies are needed to elucidate exact mechanisms and causality, we propose that an altered microbiome, gastrointestinal symptoms, and immune dysregulation may be associated with the ADHD phenotypes.

Associations between attention-deficit/hyperactivity disorder symptoms and dietary habits in elementary school children

OBJECTIVE

The aim of the present study was to investigate the associations between dietary habits and attention deficit/hyperactivity disorder (ADHD) symptoms in elementary school children.

METHODS

The parents of 16,831 participating children assessed the ADHD symptoms of their children by responding to the Korean version of the ADHD rating scale (K-ARS). Parents also responded to the food habit questionnaire, which consists of 8 items regarding the eating pace, the frequency of overeating, and patterns of eating six types of food: fast food, soft drinks, instant noodles, fruit and vegetables, and milk.

RESULTS

K-ARS scores were positively associated with higher consumption of foods categorized as unhealthy, including fast food, soft drinks, and instant noodles, and negatively associated with higher consumption of fruit and vegetables categorized as healthy foods. K-ARS scores were also higher in the groups who overate more frequently and ate faster or slower compared to other family members.

CONCLUSION

Our findings may provide useful clinical information for dietary interventions in children with ADHD.

Rationale for Dietary Antioxidant Treatment of ADHD

Increasing understanding arises regarding disadvantages of stimulant medication in children with ADHD (Attention-Deficit Hyperactivity Disorder). This review presents scientific findings supporting dietary antioxidant treatment of ADHD and describes substantial alterations in the immune system, epigenetic regulation of gene expression, and oxidative stress regulation in ADHD. As a result, chronic inflammation and oxidative stress could develop, which can lead to ADHD symptoms, for example by chronic T-cell-mediated neuroinflammation, as well as by neuronal oxidative damage and loss of normal cerebral functions. Therefore, modulation of immune system activity and oxidant-antioxidant balance using nutritional approaches might have potential in ADHD treatment. The use of natural antioxidants against oxidative conditions is an emerging field in the management of neurodegenerative diseases. Dietary polyphenols, for example, have antioxidant capacities as well as immunoregulatory effects and, therefore, appear appropriate in ADHD therapy. This review can stimulate the development and investigation of dietary antioxidant treatment in ADHD, which is highly desired.

Gut microbiota profiles in treatment-naïve children with attention deficit hyperactivity disorder

BACKGROUNDS

Although increasing evidence suggests a role for the gut microbiota in neurodevelopment, the actual structure and composition of microbiota in children with attention-deficit/hyperactivity disorder (ADHD) remain unclear.

METHODS

Thus, the present study aimed to define the characteristics of gut microbiota in treatment-naive children with ADHD and to assess their relationship with the severity of ADHD symptoms. High-throughput pyrosequencing was used to investigate the microbiota composition in fecal matter from 51 children with ADHD and 32 healthy controls (HC).

RESULTS

An operational taxonomical unit (OTU)-level analysis revealed a significant decrease in the fractional representation of Faecalibacterium in children with ADHD compared to HC. In individuals with ADHD, the abundance of Faecalibacterium was negatively associated with parental reports of ADHD symptoms. However, there was no significant difference in alpha diversity between the ADHD and control groups.

CONCLUSIONS

This present findings support the involvement of microbiota alteration in psychiatric diseases and Faecalibacterium may represent a potential novel marker of gut microbiota in ADHD. Future studies are needed to validate these findings and to elucidate the temporal and causal relationships between these variables.

Intestinal Microbiota Influences Non-intestinal Related Autoimmune Diseases

The human body is colonized by millions of microorganisms named microbiota that interact with our tissues in a cooperative and non-pathogenic manner. These microorganisms are present in the skin, gut, nasal, oral cavities, and genital tract. In fact, it has been described that the microbiota contributes to balancing the immune system to maintain host homeostasis. The gut is a vital organ where microbiota can influence and determine the function of cells of the immune system and contributes to preserve the wellbeing of the individual. Several articles have emphasized the connection between intestinal autoimmune diseases, such as Crohn's disease with dysbiosis or an imbalance in the microbiota composition in the gut. However, little is known about the role of the microbiota in autoimmune pathologies affecting other tissues than the intestine. This article focuses on what is known about the role that gut microbiota can play in the pathogenesis of non-intestinal autoimmune diseases, such as Grave's diseases, multiple sclerosis, type-1 diabetes, systemic lupus erythematosus, psoriasis, schizophrenia, and autism spectrum disorders. Furthermore, we discuss as to how metabolites derived from bacteria could be used as potential therapies for non-intestinal autoimmune diseases.

Poor cognitive ageing: Vulnerabilities, mechanisms and the impact of nutritional interventions

BACKGROUND

Ageing is a highly complex process marked by a temporal cascade of events, which promote alterations in the normal functioning of an individual organism. The triggers of normal brain ageing are not well understood, even less so the factors which initiate and steer the neuronal degeneration, which underpin disorders such as dementia. A wealth of data on how nutrients and diets may support cognitive function and preserve brain health are available, yet the molecular mechanisms underlying their biological action in both normal ageing, age-related cognitive decline, and in the development of neurodegenerative disorders have not been clearly elucidated.

OBJECTIVES

This review aims to summarise the current state of knowledge of vulnerabilities that predispose towards dysfunctional brain ageing, highlight potential protective mechanisms, and discuss dietary interventions that may be used as therapies. A special focus of this paper is on the impact of nutrition on neuroprotection and the underlying molecular mechanisms, and this focus reflects the discussions held during the 2nd workshop 'Nutrition for the Ageing Brain: Functional Aspects and Mechanisms' in Copenhagen in June 2016. The present review is the most recent in a series produced by the Nutrition and Mental Performance Task Force under the auspice of the International Life Sciences Institute Europe (ILSI Europe).

CONCLUSION

Coupling studies of cognitive ageing with studies investigating the effect of nutrition and dietary interventions as strategies targeting specific mechanisms, such as neurogenesis, protein clearance, inflammation, and non-coding and microRNAs is of high value. Future research on the impact of nutrition on cognitive ageing will need to adopt a longitudinal approach and multimodal nutritional interventions will likely need to be imposed in early-life to observe significant impact in older age.

Anterior cingulate cortex glutamate and its association with striatal functioning during cognitive control

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by structural, functional and neurochemical alterations of the fronto-striatal circuits and by deficits in cognitive control. In particular, ADHD has been associated with impairments in top-down fronto-striatal glutamate-signalling. However, it is unknown whether fronto-striatal glutamate is related to cognitive control dysfunction. Here we explored whether and how anterior cingulate cortex (ACC) glutamate relates to striatal BOLD-responses during cognitive control. We used proton magnetic resonance spectroscopy to evaluate glutamate-to-creatine ratios in 62 participants (probands with ADHD n=19, unaffected siblings n=24 and typical controls n=19, mean age=20.4). Spectra were collected from the ACC and the dorsal striatum and glutamate-to-creatine ratios were extracted. Thirty-two participants additionally took part in a functional magnetic resonance imaging (fMRI) Stroop task to investigate neural responses during cognitive control. Given small sample sizes we report all effects with p<0.10 along with effect sizes. ADHD subjects showed decreased glutamate-to-creatine ratios in the ACC (F=3.81, p=0.059, η_p²=0.104; medium to large effect-size) compared with controls. Importantly, decreased ACC glutamate-to-creatine ratios were associated with increased striatal BOLD-responses during cognitive control (rho=-0.41, p=0.019; medium effect-size), independent of diagnosis. Increased striatal responses tended to be associated with more errors during the task and more hyperactivity/impulsivity symptoms (rho=0.34, p=0.058 and rho=0.33, p=0.068, respectively); the latter two being correlated too (rho=0.37, p=0.037), all with medium effect sizes. Our results suggest that ACC glutamate in ADHD might be associated with striatal (dys)functioning during the Stroop task, supporting the role of fronto-striatal glutamate in cognitive control.

Identification and Antimicrobial Susceptibility Testing of Anaerobic Bacteria: Rubik's Cube of Clinical Microbiology?

Anaerobic bacteria have pivotal roles in the microbiota of humans and they are significant infectious agents involved in many pathological processes, both in immunocompetent and immunocompromised individuals. Their isolation, cultivation and correct identification differs significantly from the workup of aerobic species, although the use of new technologies (e.g., matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, whole genome sequencing) changed anaerobic diagnostics dramatically. In the past, antimicrobial susceptibility of these microorganisms showed predictable patterns and empirical therapy could be safely administered but recently a steady and clear increase in the resistance for several important drugs (β-lactams, clindamycin) has been observed worldwide. For this reason, antimicrobial susceptibility testing of anaerobic isolates for surveillance purposes or otherwise is of paramount importance but the availability of these testing methods is usually limited. In this present review, our aim was to give an overview of the methods currently available for the identification (using phenotypic characteristics, biochemical testing, gas-liquid chromatography, MALDI-TOF MS and WGS) and antimicrobial susceptibility testing (agar dilution, broth microdilution, disk diffusion, gradient tests, automated systems, phenotypic and molecular resistance detection techniques) of anaerobes, when should these methods be used and what are the recent developments in resistance patterns of anaerobic bacteria.