Gut microbiome and attention deficit/hyperactivity disorder: a systematic review

Archaea methanogens are associated with cognitive performance through the shaping of gut microbiota, butyrate and histidine metabolism

The relationship between bacteria, cognitive function and obesity is well established, yet the role of archaeal species remains underexplored. We used shotgun metagenomics and neuropsychological tests to identify microbial species associated with cognition in a discovery cohort (IRONMET, n = 125). Interestingly, methanogen archaeas exhibited the strongest positive associations with cognition, particularly Methanobrevibacter smithii (M. smithii). Stratifying individuals by median-centered log ratios (CLR) of M. smithii (low and high M. smithii groups: LMs and HMs) revealed that HMs exhibited better cognition and distinct gut bacterial profiles (PERMANOVA p = 0.001), characterized by increased levels of Verrucomicrobia, Synergistetes and Lentisphaerae species and reduced levels of Bacteroidetes and Proteobacteria. Several of these species were linked to the cognitive test scores. These findings were replicated in a large-scale validation cohort (Aging Imageomics, n = 942). Functional analyses revealed an enrichment of energy, butyrate, and bile acid metabolism in HMs in both cohorts. Global plasma metabolomics by CIL LC-MS in IRONMET identified an enrichment of methylhistidine, phenylacetate, alpha-linolenic and linoleic acid, and secondary bile acid metabolism associated with increased levels of 3-methylhistidine, phenylacetylgluamine, adrenic acid, and isolithocholic acid in the HMs group. Phenylacetate and linoleic acid metabolism also emerged in the Aging Imageomics cohort performing untargeted HPLC-ESI-MS/MS metabolic profiling, while a targeted bile acid profiling identified again isolithocholic acid as one of the most significant bile acid increased in the HMs. 3-Methylhistidine levels were also associated with intense physical activity in a second validation cohort (IRONMET-CGM, n = 116). Finally, FMT from HMs donors improved cognitive flexibility, reduced weight, and altered SCFAs, histidine-, linoleic acid- and phenylalanine-related metabolites in the dorsal striatum of recipient mice. M. smithii seems to interact with the bacterial ecosystem affecting butyrate, histidine, phenylalanine, and linoleic acid metabolism with a positive impact on cognition, constituting a promising therapeutic target to enhance cognitive performance, especially in subjects with obesity.

Gut microbiome changes with micronutrient supplementation in children with attention-deficit/hyperactivity disorder: the MADDY study

Micronutrients have demonstrated promise in managing inattention and emotional dysregulation in children with attention-deficit/hyperactivity disorder (ADHD). One plausible pathway by which micronutrients improve symptoms is the gut microbiome. This study examines changes in fecal microbial composition and diversity after micronutrient supplementation in children with ADHD (N = 44) and highlights potential mechanisms responsible for the behavioral improvement, as determined by blinded clinician-rated global improvement response to micronutrients. Participants represent a sub-group of the Micronutrients for ADHD in Youth (MADDY) study, a double blind randomized controlled trial in which participants received micronutrients or placebo for 8 weeks, followed by an 8-week open extension. Stool samples collected at baseline, week 8, and week 16 were analyzed using 16S rRNA amplicon sequencing targeting the V4 hypervariable region. Pairwise compositional analyses investigated changes in fecal microbial composition between micronutrients versus placebo and responders versus non-responders. A significant change in microbial evenness, as measured by alpha diversity, and beta-diversity, as measured by Bray-Curtis, was observed following micronutrients supplementation. The phylum Actinobacteriota decreased in the micronutrients group compared to placebo. Two butyrate-producing bacterial families: Rikenellaceae and Oscillospiraceae, exhibited a significant increase in change following micronutrients between responders versus non-responders. These findings suggest that micronutrients modulated the composition of the fecal microbiota and identified specific bacterial changes associated with micronutrient responders.

Gut microbiome differences in children with Attention Deficit Hyperactivity Disorder and Autism Spectrum Disorder and effects of probiotic supplementation: A randomized controlled trial

BACKGROUND

Emerging evidence suggests a significant role of gut microbiota on neurodevelopmental disorders, including Attention Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD).

AIMS

Our study aimed to compare gut microbiota composition between these disorders and evaluate the effect of probiotic supplementation.

METHODS

We conducted a 12-week randomized, double-blind, placebo-controlled trial with 80 children aged 5-14 years (39 with ADHD, 41 with ASD). Baseline and post-intervention fecal samples were analyzed using 16S rRNA gene sequencing to identify changes in gut microbiota composition.

RESULTS

We identified 22 taxa differentiating ADHD and ASD (AUC = 0.939), characterised by increased presence of Clostridia, Ruminococcaceae, and Lachnospiraceae in ADHD, and Bacteroides, Bacilli and Actinobacteria in ASD. These differences remained after accounting for potential confounders. ASD children receiving probiotics had significant increases in Chao 1, Fisher's alpha, and Shannon indices whereas no significant differences in α and β-diversity were found in ADHD. In ADHD, bacteria with potential adverse effects were under-represented. In ASD, the abundance of Eggerthellaceae, and other taxa associated with gastrointestinal problems and anxiety was decreased.

CONCLUSION

Variations in gut microbiota may influence responses in ADHD and ASD. Probiotic supplementation favorably altered gut microbiota composition, offering insights for future therapeutic strategies targeting the microbiome in neurodevelopmental disorders.

WHAT THIS PAPER ADDS

Recent research underscores the role of gut microbiota in ADHD and ASD, indicating that diet can significantly influence microbiota composition and potentially manage these neurodevelopmental disorders. This study reveals distinct differences in gut microbiota composition between children with ADHD and ASD and demonstrates that probiotic supplementation can modulate specific microbial genera in each disorder. These findings pave the way for the development of innovative microbiome-targeted therapies, offering a new avenue for the treatment of neurodevelopmental disorders. Understanding this relationship is crucial for designing future interventions.

Preventive effect of quinoa polysaccharides on lipopolysaccharide-induced inflammation in mice through gut microbiota regulation

Inflammation significantly influences the development of gastrointestinal (GI) diseases such as inflammatory bowel diseases (IBD)and ulcerative colitis, which disrupts normal digestive functions, leading to tissue damage and various symptoms. This research explores the preventive effects of quinoa polysaccharides (QPS) on lipopolysaccharide (LPS)-induced systemic acute inflammation in mice and their mechanism of action. The findings revealed that QPS alleviated LPS-induced inflammation symptoms, enhanced the mice behavior score and their immune organ index, reduced pro-inflammatory cytokines (IL-6, TNF-α and IL-1β) levels, elevated the expression level of tight junction proteins (ZO-1, MUC2). Additionally, the levels of superoxide dismutase (SOD), malondialdehyde (MDA) and total antioxidant capacity (T-AOC) were improved via QPS administration. Further, our research suggested that QPS enhanced the diversity and abundance of gut microbiota compared to that of LPS mice, leading to an increase in the short-chain fatty acids in mice feces. Linear discriminant analysis (LDA) effect size (LEfSe) showed that QPS administration could lead to a range of gut biomarkers, promoting the enhancement of polysaccharide-metabolizing bacteria. The results of 16S rRNA sequencing indicated that QPS alleviates LPS-induced inflammation by enhancing the richness of beneficial bacteria such as Bacteroides and Lactobacillus. Linear discriminant analysis (LDA) effect size (LEfSe) showed that QPS administration could lead to a range of gut biomarkers, promoting the enhancement of polysaccharide-metabolizing bacteria. UPLC Q-TOF-MS was performed to analyze metabolites in the fecal samples. LPS administration significantly altered metabolite levels detected in mice feces in which some metabolites have decreased such as xanthosine and hypoxanthine while an increase in some metabolites in mice that received QPS, metabolomics analysis showed the beneficial effects of QPS primarily mediated via amino and bile acid-related metabolism pathways. Our research could offer the basis for further studies and applications of quinoa polysaccharides.

Abscisic Acid Rescues Behavior in Adult Female Mice in Attention Deficit Disorder with Hyperactivity Model of Dopamine Depletion by Regulating Microglia and Increasing Vesicular GABA Transporter Expression

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental syndrome typically diagnosed in childhood that may persist into adulthood. Its etiology encompasses both genetic and environmental factors, with genetic studies indicating catecholamine dysfunction and epidemiological evidence emphasizing neuroinflammation as a potential trigger. To investigate the roles of inflammation and development processes in ADHD, we conducted a longitudinal behavioral study using female Swiss mice with a dopamine deficit model. We explored the impact of neonatal dopaminergic lesions, treatment with abscisic acid (ABA)-an anti-inflammatory hormone-and developmental changes by comparing behavioral patterns in juvenile and adult mice. Postmortem analyses assessed neuroinflammation through microglial morphology, NLRP3, cytokine expression, and the excitatory/inhibitory (E/I) ratio in specific brain regions. Neonatal dopaminergic lesions induced hyperactivity and hypersensitivity in juvenile mice that persisted into adulthood. In adults, increased social interaction and memory impairment were observed in lesioned mice. Brain development mitigated impulsivity, while ABA treatment reduced locomotor activity, downregulated pain sensitivity, and influenced social interaction, although it did not completely resolve cognitive deficits in lesioned adult mice. In brain regions such as the anterior cingulate cortex (ACC), posterior insular cortex (pIC), and hippocampus, lesions significantly altered microglial morphology. In the ACC, lesions increased IL-1β and TNFα levels, decreased Arg1 mRNA levels, and disrupted the E/I balance. Importantly, ABA treatment restored microglial morphology, normalized IL-1β and Arg1 expression and upregulated vGAT levels. This study demonstrates that dopamine deficits lead to microglia alterations and E/I imbalance, contributing to ADHD symptoms. While some symptoms improve with brain development, targeting microglial health in specific brain regions emerges as a promising therapeutic approach for managing ADHD.

Odoribacter splanchnicus-A Next-Generation Probiotic Candidate

As an important intestinal microorganism, Odoribacter splanchnicus frequently appears in high-throughput sequencing analyses, although pure culture research on this microorganism is not as advanced. It is widely present in the mammalian gut and is closely associated with the health status of the host and the incidence of various diseases. In recent years, changes in the abundance of O. splanchnicus have been found to be positively or negatively correlated with health issues, such as obesity, metabolic syndrome, diabetes, and intestinal inflammation. It may exhibit a dual protective or promotional role in specific diseases. Thus, it may play an important role in regulating host metabolism, immune response, and intestinal homeostasis. Additional research has revealed that O. splanchnicus can synthesize various metabolites, especially short-chain fatty acids (SCFAs), which play a key role in promoting intestinal health, enhancing energy metabolism, improving insulin resistance, and regulating immune responses in the host. Therefore, O. splanchnicus is a strong candidate for "next-generation probiotics", and its potential probiotic function provides novel ideas for the development of functional foods and the prevention and treatment of metabolic and intestinal inflammatory diseases. These findings can help develop new biological treatment strategies and optimize health management plans.

The gut microbiota-immune-brain axis: Therapeutic implications

The microbiota-gut-brain axis has major implications for human health including gastrointestinal physiology, brain function, and behavior. The immune system represents a key pathway of communication along this axis with the microbiome implicated in neuroinflammation in health and disease. In this review, we discuss the mechanisms as to how the gut microbiota interacts with the brain, focusing on innate and adaptive immunity that are often disrupted in gut-brain axis disorders. We also consider the implications of these observations and how they can be advanced by interdisciplinary research. Leveraging an increased understanding of how these interactions regulate immunity has the potential to usher in a new era of precision neuropsychiatric clinical interventions for psychiatric, neurodevelopmental, and neurological disorders.

Improving Outcomes in Mental Health (IOMH)-an Australian longitudinal clinical study of families with children with neurodevelopmental problems: cohort profile

PURPOSE

Children with neurodevelopmental disorders (NDDs) such as autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD) face a range of challenges which impact their daily functioning and that of their family. NDDs are often associated with significant mental health problems which can influence the course. The Improving Outcomes in Mental Health cohort described in this article aims to investigate the risk factors for the persistence and severity of mental health problems in children with NDDs.

PARTICIPANTS

A total of 1084 families (primary caregivers and children) were recruited from the Child Development Program at the Children's Health Queensland Hospital and Health Service in Brisbane, Australia. 1471 caregivers (female n=1036) participated in the study, which included 382 families with 2 or more caregivers participating. The children were predominantly male (71%), with the average age of all children 5.6 years.

FINDINGS TO DATE

The most prevalent child clinical diagnoses were ASD and ADHD, with half of children receiving more than one diagnosis. Caregiver reports indicated that children were experiencing clinical levels of depression (30.8%) and anxiety (27.6%). Approximately 39% of caregivers scored in the subclinical or clinical range for at least one Diagnostic and Statistical Manual of Mental Disorders measure, the majority reporting depressive problems.

FUTURE PLANS

Future plans for this data set include analysis of environmental variables such as family structure, income, school achievements and leisure activities as risk factors for the persistence of mental health problems in children with NDDs. Genetic data will be used to provide insights into the heritability of mental illness and improve prediction.

Behavioural, cognitive, and neurophysiological effects of a synbiotic supplementation enriched with pigmented corn extract or cornstarch in drug-naïve children with attention-deficit hyperactivity disorder: A randomised, double-blind, comparison-controlled clinical trial

BACKGROUND & AIMS

Considerable interest has been recently given to the potential role of the gut-brain axis (GBA) -a two-way communication network between the gut microbiota and the central nervous system- in the pathogenesis of attention-deficit hyperactivity disorder (ADHD), suggesting the potential usefulness of probiotic and synbiotic supplementations. In light of the limited available evidence, synbiotic efficacy in ADHD children not taking medications should be clarified. This study aimed to investigate the efficacy of a synbiotic dietary supplementation on fatty acids levels as well as on microbiota composition, behaviour, cognition, and brain function in children with ADHD.

METHODS

A total of 41 drug-naïve school-aged children diagnosed with ADHD were enrolled in a 3-month randomised, double-blind, comparison-controlled clinical trial, receiving either a synbiotic mix (COMP group) or the same synbiotic mix enriched with an additional extract from pigmented corn (EXP group). Changes in levels of some specific short-chain and branched-chain fatty acids were considered as primary outcomes. Secondary outcome measures included gut microbiota profiling, Child Behaviour Checklist, Conners Parent Rating Scale-revised, computerised cognitive tasks, and haemodynamic response to a Go-NoGo task measured by fNIRS.

RESULTS

No superiority of the EXP synbiotic mix was observed. Analysis of fatty acids did not reveal any significant difference between groups. Children in the COMP group reported a slightly greater improvement than those in the EXP group in focused attention and in the haemodynamic response to a cognitive task.

CONCLUSIONS

This study shows that pigmented corn extract does not enhance the effects of the synbiotic supplementation in ADHD children in terms of fatty acid production, microbiota composition, clinical, cognitive and neurophysiological measures. However, a synbiotic mix of probiotics plus prebiotic acacia fibre and cornstarch could have some promising effects on ADHD symptoms, which warrants further research. Future studies should also continue to explore the potential of fNIRS for monitoring the effects of interventions that target the GBA.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT06005506.

Effect of Probiotics on the Symptomatology of Autism Spectrum Disorder and/or Attention Deficit/Hyperactivity Disorder in Children and Adolescents: Pilot Study

The aim of this study is to investigate the impact of using probiotics with strains related to dopamine and gamma-aminobutyric acid production on clinical features of autism spectrum disorder (ASD) and/or attention deficit/hyperactivity disorder (ADHD). This randomized, controlled trial involved 38 children with ADHD and 42 children with ASD, aged 5-16 years, who received probiotics (Lactiplantibacillus plantarum and Levilactobacillus brevis 109/cfu/daily) or placebo for 12 weeks. Parent-reported symptoms were assessed using Conners' 3rd-Ed and the Social Responsiveness Scale Test, 2nd-Ed (SRS-2), and children completed the Conners Continuous Performance Test, 3rd-Ed (CPT 3) or Conners Kiddie CPT, 2nd-Ed (K-CPT 2). Executive functions, quality of life and sleep patterns were also parent-assessed. Intention-to-treat analyses, controlling for sociodemographic and nutritional covariates, revealed no significant inter-group differences in parent-reported or neuropsychological data after the probiotic intervention. However, age-stratified analyses showed improved hyperactivity-impulsivity symptoms in younger children with ASD (Cohen's d = 1.245) and ADHD (Cohen's d = 0.692). Intra-group analyses supported these findings in the aforementioned age and intervention group for both diagnoses. An improvement in impulsivity for children with ASD was also observed in the intra-group analysis of the CPT commissions scores (probiotic: p = 0.001, Cohen's d = -1.216; placebo: p = 0.013, Cohen's d = -0.721). A better comfort score (quality of life) was shown in children with ASD (probiotic: p = 0.010, Cohen's d = 0.722; placebo: p = 0.099, Cohen's d = 0.456). The probiotics used, may improve hyperactivity-impulsivity in children with ASD or/and ADHD and quality of life in children with ASD. Further research is warranted to explore probiotics as an adjunctive therapeutic intervention for NDs.Trial registration: clinicaltrials.gov Identifier: NCT05167110.

Impact of psychostimulants on microbiota and short-chain fatty acids alterations in children with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD), a common neurodevelopmental disorder in children, is associated with alterations in gut microbiota and short-chain fatty acids (SCFAs), which are metabolites influencing the gut-brain axis. Evidence suggests that psychostimulant medications, widely used to manage ADHD symptoms, may also impact gut microbiota composition and SCFA levels. This study explores these potential effects by examining gut microbiota profiles and SCFA concentrations in unmedicated and medicated children with ADHD, compared to healthy controls. Fecal samples from 30 children aged 6-12 years (10 unmedicated ADHD, 10 medicated ADHD, and 10 healthy controls) were analyzed using 16 S rRNA sequencing and targeted metabolomics. Unmedicated ADHD children show distinct gut microbiota profiles, with lower level of Tyzzerella, Prevotellaceae, and Coriobacteriaceae, compared to controls. Notably, propionic acid levels were negatively associated with ADHD symptom severity, suggesting a potential biomarker role. Medicated ADHD children showed lower gut microbial diversity, unique taxa, and lower SCFA levels, compared to unmedicated children with ADHD. These findings suggest that gut microbiota and SCFAs may be linked to ADHD symptomatology, underscoring the importance of gut-brain interactions in ADHD. This study highlights the potential of gut health monitoring as part of future ADHD management strategies.

Feeding gut microbes to nourish the brain: unravelling the diet-microbiota-gut-brain axis

The prevalence of brain disorders, including stress-related neuropsychiatric disorders and conditions with cognitive dysfunction, is rising. Poor dietary habits contribute substantially to this accelerating trend. Conversely, healthy dietary intake supports mood and cognitive performance. Recently, the communication between the microorganisms within the gastrointestinal tract and the brain along the gut-brain axis has gained prominence as a potential tractable target to modulate brain health. The composition and function of the gut microbiota is robustly influenced by dietary factors to alter gut-brain signalling. To reflect this interconnection between diet, gut microbiota and brain functioning, we propose that a diet-microbiota-gut-brain axis exists that underpins health and well-being. In this Review, we provide a comprehensive overview of the interplay between diet and gut microbiota composition and function and the implications for cognition and emotional functioning. Important diet-induced effects on the gut microbiota for the development, prevention and maintenance of neuropsychiatric disorders are described. The diet-microbiota-gut-brain axis represents an uncharted frontier for brain health diagnostics and therapeutics across the lifespan.

The Role of Diet and the Gut Microbiota in Reactive Aggression and Adult ADHD-An Exploratory Analysis

Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental condition, of-ten persistent into adulthood and accompanied by reactive aggression. Associations of diet and the gut-microbiome with ADHD as well as emotional behaviors suggest potential clinical rele-vance of both. However, studies on diet and the gut-microbiome in human reactive aggression are lacking, and should investigate the interaction between diet and the gut-microbiome leading to behavioral changes to assess their potential clinical relevance. In this study, we investigated the interaction of diet and gut-microbiota with adult ADHD and reactive aggression in 77 adults with ADHD and 76 neurotypical individuals. We studied the relationships of ADHD and reactive ag-gression with dietary patterns, bacterial community and taxonomic differences of 16S-sequenced fecal microbiome samples, and potential mediating effects of bacterial genus abundance on signifi-cant diet-behavior associations. The key findings include: (1) An association of high-energy intake with reactive aggeression scores (pFDR = 4.01 × 10-02); (2) Significant associations of several genera with either reactive aggression or ADHD diagnosis with no overlap; and (3) No significant mediation effects of the selected genera on the association of reactive aggression with the high-energy diet. Our results suggest that diet and the microbiome are linked to reactive aggression and/or ADHD individually, and highlight the need to further study the way diet and the gut-microbiome inter-act.

Revealing the gut microbiome mystery: A meta-analysis revealing differences between individuals with autism spectrum disorder and neurotypical children

The brain-gut axis intricately links gut microbiota (GM) dysbiosis to the development or worsening of autism spectrum disorder (ASD). However, the precise GM composition in ASD and the effectiveness of probiotics are unclear. To address this, we performed a thorough meta-analysis of 28 studies spanning PubMed, PsycINFO, Web of Science, Scopus, and MEDLINE, involving 1,256 children with ASD and 1042 neurotypical children, up to February 2024. Using Revman 5.3, we analyzed the relative abundance of 8 phyla and 64 genera. While individuals with ASD did not exhibit significant differences in included phyla, they exhibited elevated levels of Parabacteroides, Anaerostipes, Faecalibacterium, Clostridium, Dorea, Phascolarctobacterium, Lachnoclostridium, Catenibacterium, and Collinsella along with reduced percentages of Barnesiella, Odoribacter, Paraprevotella, Blautia, Turicibacter, Lachnospira, Pseudomonas, Parasutterella, Haemophilus, and Bifidobacterium. Notably, discrepancies in Faecalibacterium, Clostridium, Dorea, Phascolarctobacterium, Catenibacterium, Odoribacter, and Bifidobacterium persisted even upon systematic exclusion of individual studies. Consequently, the GM of individuals with ASD demonstrates an imbalance, with potential increases or decreases in both beneficial and harmful bacteria. Therefore, personalized probiotic interventions tailored to ASD specifics are imperative, rather than a one-size-fits-all approach.

Exploration of the impact of dysbiosis in the gut microbiota on microbial composition in children's neurodevelopment

OBJECTIVE

To investigate the impact of gut microbiota dysbiosis on neurodevelopment in children.

METHODS

This study included 338 children aged 0-3 years admitted to our hospital from January to December 2022, The children were divided into a normal neurodevelopment group (169 cases) and a poor neurodevelopment group (169 cases). Basic personal information and clinical data were collected through a detailed questionnaire, and the microbial composition in fecal samples was analyzed using 16S rRNA gene sequencing.

RESULTS

Children in the poor neurodevelopment group showed a significant decrease in gut microbiota diversity compared to those in the normal neurodevelopment group (Shannon index, p < 0.05). The abundance of Bifidobacterium and Veillonella genera significantly decreased (p < 0.05), while the abundance of Streptococcus genus increased significantly (p < 0.05).

CONCLUSION

There is an association between gut microbiota dysbiosis and poor neurodevelopment in children. The increased abundance of Streptococcus genus and decreased abundance of Bifidobacterium and Veillonella genera in the gut microbiota may be potential risk factors for poor neurodevelopment in preterm infants. Future research should further explore the potential beneficial effects of gut microbiota modulation on neurodevelopment in children.

Association of bisphenol A with cognitive functions and functionality in adult attention deficit hyperactivity disorder

BACKGROUND

Bisphenol A (BPA) has been linked to attention-deficit/hyperactivity disorder (ADHD) symptoms, but the effects on cognitive functions and functionality in adult ADHD have not been investigated. We investigated the associations between serum BPA with cognitive functions and functionality in adult ADHD patients.

METHODS

The levels of BPA were measured in 45 adult ADHD patients and 45 well-matched healty controls. The relationship between plastic exposure and BPA was also evaluated. Stroop test and Wisconsin Card Sorting Test were applied for neurocognitive evaluation and participants were compared in basic cognitive functions including planning, organization, abstraction, problem solving, strategy development, set shifting, cognitive flexibility, variants of attention, information processing speed, the ability to change perceptual setup and response under interference. Sheehan disability scale was applied for functionality. The association of BPA with test scores was analyzed statistically.

RESULTS

Serum BPA levels in adult ADHD patients were found to be significantly higher than in healthy controls. There was no relationship between plastic exposure and BPA levels. BPA levels showed a significant effect on functionality in terms of work field. There were significant differences between the groups in terms of cognitive functions. However, no significant correlation was found between BPA levels and cognitive functions.

CONCLUSIONS

BPA is associated with ADHD and affects functionality in the field of work, but larger-scale further studies are needed for its effect on cognitive functions.

More than just a number: the gut microbiota and brain function across the extremes of life

Understanding the interrelationship between the gut microbiota and host physiology, although still in its relative infancy, has taken important steps forward over the past decade. In the context of brain disorders including those characterized by neurodevelopmental and neurodegenerative changes there have been important advances. However, initially research involved correlational analyses, had limited translational scope, and lacked functional assessments. Thus, largescale longitudinal clinical investigations that assess causation and underlying mechanisms via in depth analysis methods are needed. In neurodegeneration research, strong causal evidence now links the gut microbiome to Alzheimer's (AD), and Parkinson's Disease (PD), as supported by human-to-animal transplantation studies. Longitudinal interventions are being conducted in AD, PD, amyotrophic lateral sclerosis, Huntington's disease, and multiple sclerosis. Neurodevelopmental research has also seen a boon in microbiome-related clinical research including in autism, Attention-deficit/hyperactivity disorder, and schizophrenia, which is confirming prior animal model work regarding the key time-windows in the gut microbiome important for infant cognition. While recent research advances represent important progress, fundamental knowledge gaps and obstacles remain. Knowing how and why the gut microbiome changes at the extremes of life will develop our mechanistic understanding and help build the evidence base as we strive toward counteracting microbial missteps with precision therapeutic interventions.

The gut-microbiome in adult Attention-deficit/hyperactivity disorder - A Meta-analysis

Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental condition that persists into adulthood in the majority of individuals. While the gut-microbiome seems to be relevant for ADHD, the few publications on gut-microbial alterations in ADHD are inconsistent, in the investigated phenotypes, sequencing method/region, preprocessing, statistical approaches, and findings. To identify gut-microbiome alterations in adult ADHD, robust across studies and statistical approaches, we harmonized bioinformatic pipelines and analyses of raw 16S rRNA sequencing data from four adult ADHD case-control studies (N ADHD =312, N NoADHD =305). We investigated diversity and differential abundance of selected genera (logistic regression and ANOVA-like Differential Expression tool), corrected for age and sex, and meta-analyzed the study results. Converging results were investigated for association with hyperactive/impulsive and inattentive symptoms across all participants. Beta diversity was associated with ADHD diagnosis but showed significant heterogeneity between cohorts, despite harmonized analyses. Several genera were robustly associated with adult ADHD; e.g., Ruminococcus_torques_group (LogOdds=0.17, p fdr =4.42×10 -2 ), which was more abundant in adults with ADHD, and Eubacterium_xylanophilum_group (LogOdds= -0.12, p fdr =6.9 x 10 -3 ), which was less abundant in ADHD. Ruminococcus_torques_group was further associated with hyperactivity/impulsivity symptoms and Eisenbergiella with inattention and hyperactivity/impulsivity (p fdr <0.05). The literature points towards a role of these genera in inflammatory processes. Irreproducible results in the field of gut-microbiota research, due to between study heterogeneity and small sample sizes, stress the need for meta-analytic approaches and large sample sizes. While we robustly identified genera associated with adult ADHD, that might overall be considered beneficial or risk-conferring, functional studies are needed to shed light on these properties.

Microbiota and nutrition as risk and resiliency factors following prenatal alcohol exposure

Alcohol exposure in adulthood can result in inflammation, malnutrition, and altered gastroenteric microbiota, which may disrupt efficient nutrient extraction. Clinical and preclinical studies have documented convincingly that prenatal alcohol exposure (PAE) also results in persistent inflammation and nutrition deficiencies, though research on the impact of PAE on the enteric microbiota is in its infancy. Importantly, other neurodevelopmental disorders, including autism spectrum and attention deficit/hyperactivity disorders, have been linked to gut microbiota dysbiosis. The combined evidence from alcohol exposure in adulthood and from other neurodevelopmental disorders supports the hypothesis that gut microbiota dysbiosis is likely an etiological feature that contributes to negative developmental, including neurodevelopmental, consequences of PAE and results in fetal alcohol spectrum disorders. Here, we highlight published data that support a role for gut microbiota in healthy development and explore the implication of these studies for the role of altered microbiota in the lifelong health consequences of PAE.

The Role of Gut Microbiota in Various Neurological and Psychiatric Disorders-An Evidence Mapping Based on Quantified Evidence

Methods

We searched PubMed, Cochrane Library, and Epistemonikos to identify systematic reviews and meta-analysis (SRs). We searched for neurological diseases and psychiatric disorders, including Alzheimer's disease (AD), attention deficit hyperactivity disorder (ADHD), amyotrophic lateral sclerosis (ALS), autism spectrum disorder (ASD), anorexia nervosa (AN), bipolar disorder (BD), eating disorder (ED), generalized anxiety disorder (GAD), major depressive disorder (MDD), multiple sclerosis (MS), obsessive compulsive disorder (OCD), Parkinson's disease (PD), posttraumatic stress disorder (PTSD), spinal cord injury (SCI), schizophrenia, and stroke. We used A Measurement Tool to Assess Systematic Reviews (AMSTAR-2) to evaluate the quality of included SRs. We also created an evidence map showing the role of gut microbiota in neurological diseases and the certainty of the evidence.

Results

In total, 42 studies were included in this evidence mapping. Most findings were obtained from observational studies. According to the AMSTAR-2 assessment, 21 SRs scored "critically low" in terms of methodological quality, 16 SR scored "low," and 5 SR scored "moderate." A total of 15 diseases have been investigated for the potential association between gut microbiome alpha diversity and disease, with the Shannon index and Simpson index being the most widely studied. A total of 12 diseases were investigated for potential link between beta diversity and disease. At the phylum level, Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, and Verrucomicrobia were more researched. At the genus level, Prevotella, Coprococcus, Parabacteroides, Phascolarctobacterium, Escherichia Shigella, Alistipes, Sutteralla, Veillonella, Odoribacter, Faecalibacterium, Bacteroides, Bifidobacterium, Dialister, and Blautia were more researched. Some diseases have been found to have specific flora changes, and some diseases have been found to have common intestinal microbiological changes.

Conclusion

We found varied levels of evidence for the associations between gut microbiota and neurological diseases; some gut microbiota increased the risk of neurological diseases, whereas others showed evidence of benefit that gut microbiota might be promising therapeutic targets for such diseases.

Targeting Neuroinflammation with Abscisic Acid Reduces Pain Sensitivity in Females and Hyperactivity in Males of an ADHD Mice Model

Attention deficit/hyperactivity disorder (ADHD) is a neurodevelopmental syndrome characterized by dopaminergic dysfunction. In this study, we aimed to demonstrate that there is a link between dopaminergic deficit and neuroinflammation that underlies ADHD symptoms. We used a validated ADHD mice model involving perinatal 6-OHDA lesions. The animals received abscisic acid (ABA), an anti-inflammatory phytohormone, at a concentration of 20 mg/L (drinking water) for one month. We tested a battery of behavior tests, learning and memory, anxiety, social interactions, and pain thresholds in female and male mice (control and lesioned, with or without ABA treatment). Postmortem, we analyzed microglia morphology and Ape1 expression in specific brain areas related to the descending pain inhibitory pathway. In females, the dopaminergic deficit increased pain sensitivity but not hyperactivity. In contrast, males displayed hyperactivity but showed no increased pain sensitivity. In females, pain sensitivity was associated with inflammatory microglia and lower Ape1 levels in the anterior cingulate cortex (ACC) and posterior insula cortex (IC). In addition, ABA treatment alleviated pain sensitivity concomitant with reduced inflammation and normalized APE1. In males, ABA reduced hyperactivity but had no significant effect on inflammation in these areas. This is the first study proving a sex-dependent association between dopamine dysfunction and inflammation in specific brain areas, hence leading to different behavioral outcomes in a mouse model of ADHD. These findings provide new clues for potential treatments for ADHD.

An overview on neurobiology and therapeutics of attention-deficit/hyperactivity disorder

Attention-Deficit/Hyperactivity Disorder (ADHD) is a prevalent psychiatric condition characterized by developmentally inappropriate symptoms of inattention and/or hyperactivity/impulsivity, which leads to impairments in the social, academic, and professional contexts. ADHD diagnosis relies solely on clinical assessment based on symptom evaluation and is sometimes challenging due to the substantial heterogeneity of the disorder in terms of clinical and pathophysiological aspects. Despite the difficulties imposed by the high complexity of ADHD etiology, the growing body of research and technological advances provide good perspectives for understanding the neurobiology of the disorder. Such knowledge is essential to refining diagnosis and identifying new therapeutic options to optimize treatment outcomes and associated impairments, leading to improvements in all domains of patient care. This review is intended to be an updated outline that addresses the etiological and neurobiological aspects of ADHD and its treatment, considering the impact of the "omics" era on disentangling the multifactorial architecture of ADHD.

Is fecal microbiota transplantation a useful therapeutic intervention for psychiatric disorders? A narrative review of clinical and preclinical evidence

The therapeutic management of psychiatric disorders is currently confronted with a critical need to find new therapeutic interventions due to the high rates of non-responsivity or low responsivity in the key pathologies, e.g. schizophrenia spectrum disorders, alcohol use disorders, or major depressive disorder. The modulation of intestinal microbiota has been explored in various organic and psychiatric dysfunctions, with different degrees of success. However, this type of intervention may represent a helpful add-on at a conceptual level since it does not associate negative pharmacokinetics interactions, significant adverse events, or risk for non-adherence in the long term. Oral administration of pre-, pro-, or synbiotics, and especially the treatment with fecal microbiota transplantation (FMT), are methods still in their early research phase for patients with psychiatric disorders, therefore an exploration of data regarding the potential benefits and adverse events of FMT was considered necessary. In order to accomplish this purpose, the available results of research dedicated to each category of psychiatric disorders, starting with depressive and anxiety disorders, continuing with schizophrenia, substance use disorders, and finishing with disorders diagnosed during childhood, were presented in this paper. Seven clinical trials, 16 preclinical studies, three meta-analyses/systematic reviews, and six case reports, all of these representing ten distinct categories of psychiatric disorders or manifestations, have been reviewed. Mood disorders, anxiety disorders, and alcohol dependence have been the most extensively investigated clinical entities from the FMT efficacy and tolerability perspective, and reviewed data are generally promising. Based on the current status of research, FMT may be considered a helpful intervention in specific psychiatric pathologies. Still, this review showed that most of the information is derived from entirely preclinical studies. Therefore, clinical trials with sound methodology and more participants are needed to clarify FMT's benefits and risks in psychiatric disorders.

Eating Patterns and Dietary Interventions in ADHD: A Narrative Review

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental disorders in childhood, affecting ~7% of children and adolescents. Given its adverse health outcomes and high healthcare and societal costs, other treatment options beyond pharmacotherapy have been explored. Case-control studies have shown that dietary patterns may influence the risk of ADHD, and specific dietary interventions have been proposed as coadjuvant treatments in this disorder. These include nutritional supplements, gut microbiome-targeted interventions with biotics, and elimination diets. The purpose of this review is to examine which dietary patterns are most associated with ADHD and to summarize the existing evidence for the clinical use of dietary interventions. The literature showed that non-healthy dietary patterns were positively associated with ADHD, whereas healthy patterns were negatively associated. As for nutritional supplements, only vitamin D and vitamin D + magnesium appeared to improve ADHD symptoms when baseline levels of vitamin D were insufficient/deficient. Regarding biotics, evidence was only found for Lactobacillus rhamnosus GG and for multi-species probiotic supplementation. Elimination diets have scarce evidence and lead to nutritional deficiencies, so caution is advised. Overall, more robust scientific evidence is required for these dietary interventions to be implemented as part of ADHD therapy.