Environmental influence on neurodevelopmental disorders: Potential association of heavy metal exposure and autism

The Health-Related and Learning Performance Effects of Air Pollution and Other Urban-Related Environmental Factors on School-Age Children and Adolescents-A Scoping Review of Systematic Reviews

PURPOSE OF REVIEW

This scoping review aims to assess the impact of air pollution, traffic noise, heat, and green and blue space exposures on the physical and cognitive development of school-age children and adolescents. While existing evidence indicates adverse effects of transport-related exposures on their health, a comprehensive scoping review is necessary to consolidate findings on various urban environmental exposures' effects on children's development.

RECENT FINDINGS

There is consistent evidence on how air pollution negatively affects children's cognitive and respiratory health and learning performance, increasing their susceptibility to diseases in their adult life. Scientific evidence on heat and traffic noise, while less researched, indicates that they negatively affect children's health. On the contrary, green space exposure seems to benefit or mitigate these adverse effects, suggesting a potential strategy to promote children's cognitive and physical development in urban settings. This review underscores the substantial impact of urban exposures on the physical and mental development of children and adolescents. It highlights adverse health effects that can extend into adulthood, affecting academic opportunities and well-being beyond health. While acknowledging the necessity for more research on the mechanisms of air pollution effects and associations with heat and noise exposure, the review advocates prioritizing policy changes and urban planning interventions. This includes minimizing air pollution and traffic noise while enhancing urban vegetation, particularly in school environments, to ensure the healthy development of children and promote lifelong health.

Developmental iron exposure induces locomotor alterations in Drosophila: Exploring potential association with oxidative stress

Prenatal iron (Fe) exposure has been associated with learning and cognitive impairments, which may be linked to oxidative stress resulting from elevated Fe levels and harm to the vulnerable brain. Drosophila melanogaster has contributed to our understanding of molecular mechanisms involved in neurological conditions. This study aims to explore Fe toxicity during D. melanogaster development, assessing oxidative stress and investigating behaviors in flies that are related to neurological conditions in humans. To achieve this goal, flies were exposed to Fe during the developmental period, and biochemical and behavioral analyses were conducted. The results indicated that 20 mM Fe decreased fly hatching by 50 %. At 15 mM, Fe exposure increased lipid peroxidation, and GSH levels decreased starting from 5 mM of Fe. Superoxide Dismutase activity was enhanced at 15 mM, while Glutathione S-Transferase activity was inhibited from 5 mM. Although chronic Fe exposure did not alter acetylcholinesterase (AChE) activity, flies exhibited reduced locomotion, increased grooming, and antisocial behavior from 5 mM of Fe. This research highlights potential Fe toxicity risks during development and underscores the utility of D. melanogaster in unraveling neurological disorders, emphasizing its relevance for future research.

Manganese in autism spectrum disorder and attention deficit hyperactivity disorder: The state of the art

The objective of the present narrative review was to synthesize existing clinical and epidemiological findings linking manganese (Mn) exposure biomarkers to autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD), and to discuss key pathophysiological mechanisms of neurodevelopmental disorders that may be affected by this metal. Existing epidemiological data demonstrated both direct and inverse association between Mn body burden and ASD, or lack of any relationship. In contrast, the majority of studies revealed significantly higher Mn levels in subjects with ADHD, as well as direct relationship between Mn body burden with hyperactivity and inattention scores in children, although several studies reported contradictory results. Existing laboratory studies demonstrated that impaired attention and hyperactivity in animals following Mn exposure was associated with dopaminergic dysfunction and neuroinflammation. Despite lack of direct evidence on Mn-induced neurobiological alterations in patients with ASD and ADHD, a plethora of studies demonstrated that neurotoxic effects of Mn overexposure may interfere with key mechanisms of pathogenesis inherent to these neurodevelopmental disorders. Specifically, Mn overload was shown to impair not only dopaminergic neurotransmission, but also affect metabolism of glutamine/glutamate, GABA, serotonin, noradrenaline, thus affecting neuronal signaling. In turn, neurotoxic effects of Mn may be associated with its ability to induce oxidative stress, apoptosis, and neuroinflammation, and/or impair neurogenesis. Nonetheless, additional detailed studies are required to evaluate the association between environmental Mn exposure and/or Mn body burden and neurodevelopmental disorders at a wide range of concentrations to estimate the potential dose-dependent effects, as well as environmental and genetic factors affecting this association.

Melatonin is a Neuroprotective and Antioxidant Agent against Neurotoxicity Induced by an Intrahippocampal Injection of Nickel in Rats

The investigation into the hippocampal function and its response to heavy metal exposure is crucial for understanding the mechanisms underlying neurotoxicity, this can potentially inform strategies for mitigating the adverse effects associated with heavy metal exposure. Melatonin is an essential neuromodulator known for its efficacy as an antioxidant. In this study, we aimed to determine whether melatonin could protect against Nickel (Ni) neurotoxicity. To achieve this, we performed an intracerebral injection of Ni (300 µM NiCl2) into the right hippocampus of male Wistar rats, followed by melatonin treatment. Based on neurobehavioral and neurobiochemical assessments, our results demonstrate that melatonin efficiently enhances Ni-induced behavioral dysfunction and cognitive impairment. Specifically, melatonin treatment positively influences anxious behavior, significantly reduces immobility time in the forced swim test (FST), and improves learning and spatial memory abilities. Moreover, neurobiochemical assays revealed that melatonin treatment modulates the Ni-induced alterations in oxidative stress balance by increasing antioxidant enzyme activities, such as superoxide dismutase (SOD) and catalase (CAT). Additionally, we observed that melatonin significantly attenuated the increased levels of lipid peroxidation (LPO) and nitric oxide (NO). In conclusion, the data from this study suggests that melatonin attenuates oxidative stress, which is the primary mechanism responsible for Ni-induced neurotoxicity. Considering that the hippocampus is the main structure involved in the pathology associated with heavy metal intoxication, such as Ni, these findings underscore the potential therapeutic efficacy of melatonin in mitigating heavy metal-induced brain damage.

Health risk assessments of heavy metals and trace elements exposure in the breast milk of lactating mothers in the Northeastern Iran

Mother's breast milk is a natural and complete food for infants but can be a main source of exposure to toxic pollutants. These pollutants can negatively affect the health of the infant. Therefore, conducting biomonitoring surveys is essential to evaluate such health effects in toxicological research. This study aimed to estimate the probable health risks for infants exposed to essential and non-essential trace elements through breast milk ingestion. This descriptive-analytical, cross-sectional study was performed on 90 breastfeeding mothers referred to the health centers in Mashhad, Iran in January 2021. The health risk assessments (carcinogenic and non-carcinogenic risk) were estimated using chronic daily intake (CDI), hazard quotient (HQ), hazard index (HI), and lifetime carcinogenic risk (CR), which were recommended by the US Environmental Protection Agency (US EPA). The results of the HQ values of trace elements through ingestion exposure for arsenic (90%), copper (90%), zinc (40%), and iron (10%) exceeded the threshold of HQ, and arsenic (66.59%), copper (16.91%), and zinc (9.68%) and iron (4.57%) had the highest contribution to increasing the HI index. The average value of CR was 5. 08 × 10-3. Chromium and iron showed significant relationships (P<0.05) with education level and disease background in this study, and the concentration of chromium, iron, and zinc in the breast milk samples significantly changed during lactation stages (P<0.05). Overall, the risk of carcinogenicity through exposure to breast milk for infants was higher than the safety level of US EPA risk. Therefore, there could be a potential health risk of trace elements, particularly arsenic, copper, and zinc for infants in Mashhad, Iran through the consumption of mothers' breast milk. More efforts are required to control and reduce routes of receiving trace elements in breastfeeding mothers by the competent authorities.

Autism spectrum disorder: Cadmium and mercury concentrations in different biological samples, a systematic literature review and meta-analysis of human studies

The present study was conducted to investigate the differences in cadmium (Cd) and mercury (Hg) concentrations between children with autism spectrum disorder (ASD) and controls. In this systematic review and meta-analysis study, three thousand one hundred forty-five studies were collected from scientific databases including Web of Science, Scopus, PubMed, and Google Scholar from January 2000 to October 2022 and were investigated for eligibility. As a result, 37 studies published in the period from 2003 to 2022 met our inclusion criteria and were considered in the meta-analysis. The heterogeneity assumption was evaluated using the Chi-squared-based Q-test and I-squared (I2) statistics. The pooled estimates were shown in the forest plots with Hedges' g (95% confidence interval) values. The random effects model demonstrated that there is no significant difference in the blood (Hedges' g: 0.14, 95% CI: 0.45, 0.72, p > 0.05), hair (Hedges' g: 0.12, 95% CI: 0.26, 0.50, p > 0.05), and urinary (Hedges' g: 0.05, 95% CI: 0.86, 0.76, p > 0.05) Cd levels of the case group versus control subjects. Moreover, the pooled findings of studies showed no significant difference in the blood (Hedges' g: 1.69, 95% CI: 0.09, 3.48, p > 0.05), hair (Hedges' g: 3.42, 95% CI: 1.96, 8.80, p > 0.05), and urinary (Hedges' g: 0.49, 95% CI: 1.29 - 0.30, p > 0.05) Hg concentrations. The results demonstrated no significant differences in Hg and Cd concentrations in different biological samples of children with ASD compared to control subjects.

Modulation of gut microbiota with probiotics as a strategy to counteract endogenous and exogenous neurotoxicity

The existing data demonstrate that probiotic supplementation affords protective effects against neurotoxicity of exogenous (e.g., metals, ethanol, propionic acid, aflatoxin B1, organic pollutants) and endogenous (e.g., LPS, glucose, Aβ, phospho-tau, α-synuclein) agents. Although the protective mechanisms of probiotic treatments differ between various neurotoxic agents, several key mechanisms at both the intestinal and brain levels seem inherent to all of them. Specifically, probiotic-induced improvement in gut microbiota diversity and taxonomic characteristics results in modulation of gut-derived metabolite production with increased secretion of SFCA. Moreover, modulation of gut microbiota results in inhibition of intestinal absorption of neurotoxic agents and their deposition in brain. Probiotics also maintain gut wall integrity and inhibit intestinal inflammation, thus reducing systemic levels of LPS. Centrally, probiotics ameliorate neurotoxin-induced neuroinflammation by decreasing LPS-induced TLR4/MyD88/NF-κB signaling and prevention of microglia activation. Neuroprotective mechanisms of probiotics also include inhibition of apoptosis and oxidative stress, at least partially by up-regulation of SIRT1 signaling. Moreover, probiotics reduce inhibitory effect of neurotoxic agents on BDNF expression, on neurogenesis, and on synaptic function. They can also reverse altered neurotransmitter metabolism and exert an antiamyloidogenic effect. The latter may be due to up-regulation of ADAM10 activity and down-regulation of presenilin 1 expression. Therefore, in view of the multiple mechanisms invoked for the neuroprotective effect of probiotics, as well as their high tolerance and safety, the use of probiotics should be considered as a therapeutic strategy for ameliorating adverse brain effects of various endogenous and exogenous agents.

Interaction between Per- and Polyfluorinated Substances (PFAS) and Acetaminophen in Disease Exacerbation-Focusing on Autism and the Gut-Liver-Brain Axis

This review presents a new perspective on the exacerbation of autism spectrum disorder (ASD) by per- and polyfluoroalkyl substances (PFAS) through the gut-liver-brain axis. We have summarized evidence reported on the involvement of the gut microbiome and liver inflammation that led to the onset and exacerbation of ASD symptoms. As PFAS are toxicants that particularly target liver, this review has comprehensively explored the possible interaction between PFAS and acetaminophen, another liver toxicant, as the chemicals of interest for future toxicology research. Our hypothesis is that, at acute dosages, acetaminophen has the ability to aggravate the impaired conditions of the PFAS-exposed liver, which would further exacerbate neurological symptoms such as lack of social communication and interest, and repetitive behaviors using mechanisms related to the gut-liver-brain axis. This review discusses their potential interactions in terms of the gut-liver-brain axis and signaling pathways that may contribute to neurological diseases.

Exposure to different PM2.5 extracts induces gliosis and changes behavior in male rats similar to autism spectrum disorders features

Epidemiological studies have documented that exposure to fine particulate matter (PM2.5) could affect neurodevelopment, thereby leading to autism spectrum disorders (ASD). Nevertheless, there is little laboratory data to support this epidemiological evidence. In the current study, we carried out a series of experiments to assess whether developmental exposures to different extracts of PM2.5 can result in ASD-like behavioral, biochemical, and immunohistochemical characteristics in male rat offspring. PM2.5 samples were collected daily for a year, and monthly composites were extracted with an acetone-hexane mixture. The extracts were analyzed for their chemical constituents. Three groups of rats were exposed to the different PM2.5 extracts during pre- and postnatal periods. All exposed groups of rats exhibited typical behavioral features of ASD, including increased repetitive and depression-related behaviors. We also found microglia and astrocytes activation and decreased concentrations of oxytocin (OXT) in the brain regions of exposed rats compared with control rats. Comparing the current results with a prior study, the induced biological effects followed a sequence of whole particles of PM2.5 > organic extract > inorganic extract. These findings indicated that exposure to PM2.5 can elicit ASD-like features in rats and raise concerns about particulate matter as a possible trigger for the induction of ASD in humans; therefore, mitigating the contents of the PAHs and metals could reduce the PM2.5 neurotoxicity.

Mercury and Autism Spectrum Disorder: Exploring the Link through Comprehensive Review and Meta-Analysis

Mercury (Hg) is a non-essential trace metal with unique neurochemical properties and harmful effects on the central nervous system. In this study, we present a comprehensive review and meta-analysis of peer-reviewed research encompassing five crucial clinical matrices: hair, whole blood, plasma, red blood cells (RBCs), and urine. We assess the disparities in Hg levels between gender- and age-matched neurotypical children (controls) and children diagnosed with autism spectrum disorder (ASD) (cases). After applying rigorous selection criteria, we incorporated a total of 60 case-control studies into our meta-analysis. These studies comprised 25 investigations of Hg levels in hair (controls/cases: 1134/1361), 15 in whole blood (controls/cases: 1019/1345), 6 in plasma (controls/cases: 224/263), 5 in RBCs (controls/cases: 215/293), and 9 in urine (controls/cases: 399/623). This meta-analysis did not include the data of ASD children who received chelation therapy. Our meta-analysis revealed no statistically significant differences in Hg levels in hair and urine between ASD cases and controls. In whole blood, plasma, and RBCs, Hg levels were significantly higher in ASD cases compared to their neurotypical counterparts. This indicates that ASD children could exhibit reduced detoxification capacity for Hg and impaired mechanisms for Hg excretion from their bodies. This underscores the detrimental role of Hg in ASD and underscores the critical importance of monitoring Hg levels in ASD children, particularly in early childhood. These findings emphasize the pressing need for global initiatives aimed at minimizing Hg exposure, thus highlighting the critical intersection of human-environment interaction and neurodevelopment health.

Kindergarten dust heavy metal(loid) exposure associates with growth retardation in children

Heavy metal contamination from electronic waste recycling sites is present in dust found in indoor kindergartens located in e-waste recycling areas, and its potential impact on child health is a significant concern. The association between heavy metal(loid)s and the child developmental indicators is still unclear. In 2019 and 2020, we enrolled 325 and 319 children in an e-waste recycling town, respectively. Corresponding 61 and 121 dust samples were collected from roads, houses, and kindergartens in the two years. The median concentrations of metals, including Cr, Ni, Cu, Zn, and Pb exceeded the allowable limits. The highest amount of cumulative enrichment (cEF) was observed in indoor kindergarten dust (cEF = 112.3400), followed by house dust (cEF = 76.6950) and road dust (cEF = 39.7700). Children residing in the e-waste town had below-average height and weight compared to their Chinese peers. Based on linear regression analysis, the daily intake of Cd, V, Mn, and Pb in indoor kindergarten dust was found to be negatively associated with head circumference (HeC) (P < 0.05). Similarly, the daily intake of As, Cd, and Ba in indoor kindergarten dust was found to be negatively associated with chest circumference (ChC) (P < 0.05). In addition, the daily intake of As, Cd, and Ba in indoor kindergarten dust was negatively correlated with body mass index (BMI), as per the results of the study (P < 0.05). Cross-product term analysis revealed a negative correlation between daily intake of heavy metal(loid)s and HeC, ChC, and BMI, with age and sex serving as influencing factors. In conclusion, exposure to heavy metal(loid)s in indoor kindergarten dust increases the risk of growth retardation and developmental delay in children.

Hippocampal and peripheral blood DNA methylation signatures correlate at the gene and pathway level in a mouse model of autism

Autism spectrum disorders (ASD) are polygenic multifactorial disorders influenced by environmental factors. ASD-related differential DNA methylation has been found in human peripheral tissues, such as placenta, paternal sperm, buccal epithelium, and blood. However, these data lack direct comparison of DNA methylation levels with brain tissue from the same individual to determine the extent that peripheral tissues are surrogates for behavior-related disorders. Here, whole genome methylation profiling at all the possible sites throughout the mouse genome (>25 million) from both brain and blood tissues revealed novel insights into the systemic contributions of DNA methylation to ASD. Sixty-six differentially methylated regions (DMRs) share the same genomic coordinates in these two tissues, many of which are linked to risk genes for neurodevelopmental disorders and intellectual disabilities (e.g. Prkch, Ptn, Hcfc1, Mid1, and Nfia). Gene ontological pathways revealed a significant number of common terms between brain and blood (N = 65 terms), and nearly half (30/65) were associated with brain/neuronal development. Furthermore, seven DMR-associated genes among these terms contain methyl-sensitive transcription factor sequence motifs within the DMRs of both tissues; four of them (Cux2, Kcnip2, Fgf13, and Mrtfa) contain the same methyl-sensitive transcription factor binding sequence motifs (HES1/2/5, TBX2 and TFAP2C), suggesting DNA methylation influences the binding of common transcription factors required for gene expression. Together, these findings suggest that peripheral blood is a good surrogate tissue for brain and support that DNA methylation contributes to altered gene regulation in the pathogenesis of ASD.

Necroptosis in the developing brain: role in neurodevelopmental disorders

Cell death is vital to various organismal developmental processes including brain development. Apoptosis, the most recognized programmed cell death, has been linked to several developmental processes and implicated in pruning cells to provide the ultimate tissue integrity. However, more recently, other forms of non-apoptotic programmed cell death have been identified, of which necroptosis is of predominant interest. Necroptosis is a regulated form of necrosis, activated under apoptotic-deficient conditions. Tumour necrosis factor (TNF) is a major activator of necroptosis, and the process is mediated by several kinases including receptor-interacting protein kinase (RIPK) and mixed lineage kinase domain-like protein (MLKL). Potential roles for necroptosis during brain development have been muted. Necroptosis has been implicated in mediating neurological disorders, and contributing to the severity of these disorders. Here we will review the literature on the role of necroptosis in neurodevelopment, summarizing its molecular mechanisms and highlighting potential implications for disorders of the developing brain.

Efficacy of Faecal Microbiota Transplantation for the Treatment of Autism in Children: Meta-Analysis of Randomised Controlled Trials

Objective

Evidence-based research methods were applied to assess the efficacy of faecal microbiota transplantation (FMT) for the treatment of autism in children.

Methods

We searched the Chinese Biomedical Literature, CNKI, Wanfang, PubMed, Embase, Web of Science, and the Cochrane Library databases to collect randomised controlled trials on faecal microbiota transplantation for the treatment of autism in children. The search included studies published from the creation of the respective database to 5 April 2022. Literature screening, data extraction, and quality evaluation were implemented by three investigators according to the inclusion and exclusion criteria. The meta-analysis was performed using the RevMan 5.1 software.

Results

Nine studies with population-based subjects and four studies with animal-based subjects were included. Five papers were screened for the meta-analysis. The results showed that FMT markedly reduced Autism Behaviour Checklist (ABC) scores in children with autism spectrum disorder (weighted mean difference (WMD) = -14.96; 95% confidence intervals (CI), -21.68 to -8.24; P < 0.001; I ² = 0%). FMT also reduced Childhood Autism Rating Scale (CARS) scores (WMD = -6.95; 95% CI, -8.76 to -5.14; P < 0.001; I ² = 28.1%).

Conclusion

Our results indicate that FMT can benefit children with autism by reducing ABC and CARS scores, but more high-quality studies are needed to verify these results.

The role of environmental trace element toxicants on autism: A medical biogeochemistry perspective

Since genetic factors alone cannot explain most cases of Autism, the environmental factors are worth investigating as they play an essential role in the development of some cases of Autism. This research is a review paper that aims to clarify the role of the macro elements (MEs), Trace elements (TEs) and ultra-trace elements (UTEs) on human health if they are greater or less than the normal range. Aluminium (Al), cadmium Cd), lead (Pb), chromium (Cr), zinc (Zn), copper (Cu), nickel (Ni), arsenic (As), mercury (Hg), manganese (Mn), and iron (Fe) have been reviewed. Exposure to toxicants has a chemical effect that may ultimately lead to autism spectrum disorder (ASD). The Cr, As and Al are found in high concentrations in the blood of an autistic child when compared to normal child reference values. The toxic metals, particularly aluminium, are primarily responsible for difficulties in socialization and language skills disabilities. Zinc and copper are important elements in regulating the gene expression of metallothioneins (MTs), and zinc deficiency may be a risk factor for ASD pathogenesis. Autistics frequently have zinc deficiency combined with copper excess; as part of the treatment protocol, it is critical to monitor zinc and copper levels in autistic people, particularly those with zinc deficiency. Zinc deficiency is linked to epileptic seizures, which are common in autistic patients. Higher serum manganese and copper significantly characterize people who have ASD. Autistic children have significantly decreased lead and cadmium in urine, whereas they have significantly higher urine Cr. A higher level of As and Hg was found in the ASD individual's blood.

Analysis of Whole Blood and Urine Trace Elements in Children with Autism Spectrum Disorders and Autistic Behaviors

The relationship between trace elements and neurological development is an emerging research focus. We performed a case-control study to explore (1) the differences of 13 trace elements chromium (Cr), manganese (Mn), cobalt (Co), zinc (Zn), arsenic (As), selenium (Se), molybdenum (Mo), cadmium (Cd), stannum (Sn), stibium (Sb), mercury (Hg), titanium (TI), and plumbum (Pb) concentration in whole blood and urine between autism spectrum disorder (ASD) children and their typical development peers, and (2) the association between the 13 trace elements and core behaviors of ASD. Thirty ASD subjects (cases) and 30 age-sex-matched healthy subjects from Baise City, Guangxi Zhuang Autonomous Region, China, were recruited. Element analysis was carried out by inductively coupled plasma-optical emission spectrometry. Autistic behaviors were assessed using Autism Behavior Checklist (ABC), Childhood Autism Rating Scale (CARS), and Children Neuropsychological and Behavior Scale (CNBS). The whole blood concentrations of Mo (p = 0.004), Cd (0.007), Sn (p = 0.003), and Pb (p = 0.037) were significantly higher in the ASD cases than in the controls. Moreover, Se (0.393), Hg (0.408), and Mn (- 0.373) concentrations were significantly correlated between whole blood and urine levels in ASD case subjects. There were significant correlations between whole blood Sb (0.406), Tl (0.365), Mo (- 0.4237), Mn (- 0.389), Zn (0.476), and Se (0.375) levels and core behaviors of ASD. Although the mechanism of trace element imbalance in ASD is unclear, these data demonstrate that core behaviors of ASD may be affected by certain trace elements. Further studies are recommended for exploring the mechanism of element imbalance and providing corresponding clinical treatment measures.

The different trends in the burden of neurological and mental disorders following dietary transition in China, the USA, and the world: An extension analysis for the Global Burden of Disease Study 2019

Introduction

The highly processed western diet is substituting the low-processed traditional diet in the last decades globally. Increasing research found that a diet with poor quality such as western diet disrupts gut microbiota and increases the susceptibility to various neurological and mental disorders, while a balanced diet regulates gut microbiota and prevents and alleviates the neurological and mental disorders. Yet, there is limited research on the association between the disease burden expanding of neurological and mental disorders with a dietary transition.

Methods

We compared the disability-adjusted life-years (DALYs) trend by age for neurological and mental disorders in China, in the United States of America (USA), and across the world from 1990 to 2019, evaluated the dietary transition in the past 60 years, and analyzed the association between the burden trend of the two disorders with the changes in diet composition and food production.

Results

We identified an age-related upward pattern in disease burden in China. Compared with the USA and the world, the Chinese neurological and mental disorders DALY percent was least in the generation over 75 but rapidly increased in younger generations and surpassed the USA and/or the world in the last decades. The age-related upward pattern in Chinese disease burdens had not only shown in the presence of cardiovascular diseases, neoplasms, and diabetes mellitus but also appeared in the presence of depressive disorders, Parkinson's disease, Alzheimer's disease and other dementias, schizophrenia, headache disorders, anxiety disorders, conduct disorders, autism spectrum disorders, and eating disorders, successively. Additionally, the upward trend was associated with the dramatic dietary transition including a reduction in dietary quality and food production sustainability, during which the younger generation is more affected than the older. Following the increase in total calorie intake, alcohol intake, ratios of animal to vegetal foods, and poultry meat to pulses, the burdens of the above diseases continuously rose. Then, following the rise of the ratios of meat to pulses, eggs to pulses, and pork to pulses, the usage of fertilizers, the farming density of pigs, and the burdens of the above disease except diabetes mellitus were also ever-increasing. Even the usage of pesticides was positively correlated with the burdens of Parkinson's disease, schizophrenia, cardiovascular diseases, and neoplasms. Contrary to China, the corresponding burdens of the USA trended to reduce with the improvements in diet quality and food production sustainability.

Discussion

Our results suggest that improving diet quality and food production sustainability might be a promising way to stop the expanding burdens of neurological and mental disorders.

Early exposure to agricultural pesticides and the occurrence of autism spectrum disorder: a systematic review

Abstract Objective: The aim of this study was to evaluate the influence of early exposure to agricultural pesticides and their relationship with autism spectrum disorder. Data source: This systematic review was registered at PROSPERO as CRD42020204842. The subject was systematically analyzed on PubMed, Scopus, and Web of Science databases until April 2021. Only studies with humans with early exposure to agricultural pesticides and diagnosis of autism were included. Exclusion criteria were studies on pesticides for domestic or veterinary use and late exposure. There were no language and time restriction. The quality analysis of the studies used the Newcastle-Ottawa Scale. Data synthesis: Six case-control studies were included; three of them measured the route of exposure by maternal biomarkers and the others by the residence address. The studies had scores between moderate and high in the quality assessment tool. It was found high rates of association between early exposure to agricultural pesticides and autism and detection limit above the quantification for a sample of polychlorinated biphenyls, hexachlorobenzene, and dichlorodiphenyldichloroethylene. Conclusions: There is evidence concerning the exposure to agricultural pesticides in early life and the development of the autism spectrum disorder; however, more studies are required to better understand their possible association.

Insights into the role of intracellular calcium signaling in the neurobiology of neurodevelopmental disorders

Calcium (Ca²⁺) comprises a critical ionic second messenger in the central nervous system that is under the control of a wide array of regulatory mechanisms, including organellar Ca²⁺ stores, membrane channels and pumps, and intracellular Ca²⁺-binding proteins. Not surprisingly, disturbances in Ca²⁺ homeostasis have been linked to neurodegenerative disorders, such as Alzheimer's and Parkinson's diseases. However, aberrations in Ca²⁺ homeostasis have also been implicated in neuropsychiatric disorders with a strong neurodevelopmental component including autism spectrum disorder (ASD) attention-deficit hyperactivity disorder (ADHD) and schizophrenia (SCZ). While plasma membrane Ca²⁺ channels and synaptic Ca²⁺-binding proteins have been extensively studied, increasing evidence suggests a prominent role for intracellular Ca²⁺ stores, such as the endoplasmic reticulum (ER), in aberrant neurodevelopment. In the context of the current mini-review, we discuss recent findings implicating critical intracellular Ca²⁺-handling regulators such as the sarco-ER Ca²⁺ ATPase 2 (SERCA2), ryanodine receptors (RyRs), inositol triphosphate receptors (IP₃Rs), and parvalbumin (PVALB), in the emergence of ASD, SCZ, and ADHD.

Inductively coupled plasma mass spectrometry based urine metallome to construct clinical decision models for autism spectrum disorder

BACKGROUND

The global prevalence of autism spectrum disorder (ASD) is on the rise, and high levels of exposure to toxic heavy metals may be associated with this increase. Urine analysis is a noninvasive method for investigating the accumulation and excretion of heavy metals. The aim of this study was to identify ASD-associated urinary metal markers.

METHODS

Overall, 70 children with ASD and 71 children with typical development (TD) were enrolled in this retrospective case-control study. In this metallomics investigation, inductively coupled plasma mass spectrometry was performed to obtain the urine profile of 27 metals.

RESULTS

Children with ASD could be distinguished from children with TD based on the urine metal profile, with ASD children showing an increased urine metal Shannon diversity. A metallome-wide association analysis was used to identify seven ASD-related metals in urine, with cobalt, aluminum, selenium, and lithium significantly higher, and manganese, mercury, and titanium significantly lower in the urine of children with ASD than in children with TD. The least absolute shrinkage and selection operator (LASSO) machine learning method was used to rank the seven urine metals in terms of their effect on ASD. On the basis of these seven urine metals, we constructed a LASSO regression model for ASD classification and found an area under the receiver operating characteristic curve of 0.913. We also constructed a clinical prediction model for ASD based on the seven metals that were different in the urine of children with ASD and found that the model would be useful for the clinical prediction of ASD risk.

CONCLUSIONS

The study findings suggest that altered urine metal concentrations may be an important risk factor for ASD, and we recommend further exploration of the mechanisms and clinical treatment measures for such alterations.

Hydrogen Sulfide (H2S) Signaling as a Protective Mechanism against Endogenous and Exogenous Neurotoxicants

In view of the significant role of H₂S in brain functioning, it is proposed that H₂S may also possess protective effects against adverse effects of neurotoxicants. Therefore, the objective of the present review is to discuss the neuroprotective effects of H₂S against toxicity of a wide spectrum of endogenous and exogenous agents involved in the pathogenesis of neurological diseases as etiological factors or key players in disease pathogenesis. Generally, the existing data demonstrate that H₂S possesses neuroprotective effects upon exposure to endogenous (amyloid β, glucose, and advanced-glycation end-products, homocysteine, lipopolysaccharide, and ammonia) and exogenous (alcohol, formaldehyde, acrylonitrile, metals, 6-hydroxydopamine, as well as 1-methyl-4-phenyl- 1,2,3,6- tetrahydropyridine (MPTP) and its metabolite 1-methyl-4-phenyl pyridine ion (MPP)) neurotoxicants. On the one hand, neuroprotective effects are mediated by S-sulfhydration of key regulators of antioxidant (Sirt1, Nrf2) and inflammatory response (NF-κB), resulting in the modulation of the downstream signaling, such as SIRT1/TORC1/CREB/BDNF-TrkB, Nrf2/ARE/HO-1, or other pathways. On the other hand, H₂S appears to possess a direct detoxicative effect by binding endogenous (ROS, AGEs, Aβ) and exogenous (MeHg) neurotoxicants, thus reducing their toxicity. Moreover, the alteration of H₂S metabolism through the inhibition of H₂S-synthetizing enzymes in the brain (CBS, 3-MST) may be considered a significant mechanism of neurotoxicity. Taken together, the existing data indicate that the modulation of cerebral H₂S metabolism may be used as a neuroprotective strategy to counteract neurotoxicity of a wide spectrum of endogenous and exogenous neurotoxicants associated with neurodegeneration (Alzheimer's and Parkinson's disease), fetal alcohol syndrome, hepatic encephalopathy, environmental neurotoxicant exposure, etc. In this particular case, modulation of H₂S-synthetizing enzymes or the use of H₂S-releasing drugs should be considered as the potential tools, although the particular efficiency and safety of such interventions are to be addressed in further studies.

Maternal lead exposure induces sex-dependent cerebellar glial alterations and repetitive behaviors

Lead (Pb) is one of the most prevalent heavy metals we encounter daily. Although there are many reports regarding their toxic effects on humans, the effects of exposure to low lead concentrations throughout the pregnancy period on the offspring are not fully elucidated yet. This study aimed to investigate the cellular mechanisms that occur in response to lead exposure. To this end, we administered lead-containing water to pregnant mice from the day of conception till delivery or till day 28 postnatally. Furthermore, we performed neurodevelopmental disorder-related behavior tests and RNA-sequencing analysis. We used both genders for all experiments because neurodevelopmental disorders usually show several sex-dependent differences. The results revealed increased levels of gliosis in the cerebella of lead-exposed pups compared to those in littermates belonging to the control group. Additionally, we observed altered behaviors of male mice in the autism spectrum disorder-related tests. RNA-sequencing results revealed changes in gamma-aminobutyric acid (GABA) signaling in the lead-exposed mouse model. Specifically, the lead-exposed male mice showed decreased monoamine oxidase B and increased levels of diamine oxidase enzyme, which is related to the synthesis of GABA in astrocytes. These findings demonstrate sex-dependent basal developmental changes in glial cells and an increased prevalence of autistic-like behaviors in the young pups of mothers exposed to lead during pregnancy.

Exposure to multiple metals and the risk of dyslexia - A case control study in Shantou, China

Environmental heavy metal exposure has been considered to be the risk factor for neurodevelopmental disorders in children. However, the available data on the associations between multiple metals exposure and the risk of dyslexia in China are limited. The purpose of our study was to examine the associations between urinary metal concentrations and Chinese dyslexia risk. A total of 56 Chinese dyslexics and 60 typically developing children were recruited. The urinary concentration of 13 metals were measured by inductively coupled plasma-mass spectrometer (ICP-MS). Binary logistic regression and the Probit extension of Bayesian kernel machine regression (BKMR-P) were used to explore the associations between multiple metal exposure and the risk of Chinese dyslexia. Our results indicated that Co, Zn and Pb were significantly associated with Chinese dyslexia in the multiple-metal exposure model. After adjusting the covariates, a positive association was observed between Pb and the risk of Chinese dyslexia, with the odds ratio (OR) in the highest quartiles of 6.81 (95%CI: 1.07-43.19; p-trend = 0.024). Co and Zn were negatively associated with the risk of Chinese dyslexia. Compared to the lowest quartile, the ORs of Co and Zn in the highest quartile are 0.13 (95%CI: 0.02-0.72; p-trend = 0.026) and 0.18 (95%CI: 0.04-0.88; p-trend = 0.038), respectively. In addition, BKMR-P analysis indicated that with the cumulative level across Co, Zn and Pb increased, the risk of Chinese dyslexia gradually declined and then rebounded, albeit non-significantly, and Pb was the major contributor in this association. In general, the urinary concentrations of Co, Zn and Pb were significantly associated with Chinese dyslexia. More prospective studies are needed to confirm the health effects of multiple metals exposure in children with Chinese dyslexia.

Multiple exposure to methylmercury aggravates DNA damage in the BTBR T + Itpr3 tf/J autistic mouse model: the role of DNA repair efficiency

Environmental and genetic factors have been recognized to play major roles in the pathogenesis of autism. Here we examined the BTBR T⁺Itpr3^tf/J (BTBR) mice's susceptibility, an autistic model, to the genotoxic effects and DNA repair dysregulation of methylmercury. Micronuclei formation and oxidative DNA damage were analyzed using the micronucleus/fluorescence in situ hybridization test and modified comet assay, respectively. The results showed higher centromeric-positive micronuclei and oxidative DNA damage in BTBR mice exposed to methylmercury than the unexposed mice, which indicates that mutagenesis aggravated in BTBR mice after methylmercury exposure. Lipid peroxides in BTBR mice were significantly elevated, with a decrease in reduced/oxidized glutathione ratio after methylmercury exposure, indicating an augmenting oxidant-antioxidant imbalance. The expression of several genes involved in DNA repair was markedly altered in BTBR mice after methylmercury exposure as evaluated via PCR array and RT-PCR analyses. Declining of the antioxidant defense and dysregulation in DNA repair process after methylmercury exposure may explain the aggravated genotoxic susceptibility of BTBR mice. Thus, autistic individuals exposed to methylmercury must be under regular medical follow-up through standard timetabled medical laboratory inquiry to allow for early recognition of any mutagenic changes. Additionally, strategies that elevate cellular antioxidants/DNA repair efficiency may counteract methylmercury-induced genotoxicity.

Environmental Influences on the Behavioural and Emotional Outcomes of Children: A Network Analysis

Background: Intellectual developmental disorders are a serious source of health morbidity with negative consequences for adults as well as children. However, there is limited evidence on the environmental, trace element, behavioural, and emotional outcomes in children. Here, we investigated whether there is any association between child behaviour and emotional outcomes and micronutrients using network analysis. Methods: A cross-sectional study was conducted in 9-year-old children within a Pacific Island Families study birth cohort. Elemental concentration was determined in children’s toenails after acid digestion and analysed using inductively coupled plasma mass spectrometry. We used network analysis to identify closely associated trace elements and tested the directions and strength of these trace elements. MANCOVA were used to identify the significant associations between individual elements and the behavioural/emotional function of the children using the children behaviour checklist (CBCL). At the final step, quantile regression analysis was used to assess and quantify the identified associations between CBCL function scores and manganese, adjusted by sex, ethnicity, and standardized BMI. Results: Three major nutrient networks were identified. In the Mn network, Mn was strongly positively associated with Al (0.63) and Fe (r = 0.65) and moderately associated with Pb (r = 0.45) and Sb (r = 0.42). Al was also strongly associated with Fe (r = 0.9). Children in the second or third clinical group, with an elevated externalized CBCL score, had a much higher mean and median level of Mn as compared to the normal range group. The aggression score was significantly associated with Mn concentration and sex. Higher Mn concentrations were associated with a higher aggression score. A 1 ug/g unit increase in Mn was associated with a 2.44-fold increase (95% confidence interval: 1.55–4.21) in aggression score, and boys had higher median aggression score than girls (difference: 1.7, 95% CI: 0.9–2.8). Attention and rule breaking scores were both significantly associated with Mn concentration. Higher Mn concentrations were associated with higher attention behaviour problem and rule breaking scores. A 1 ug/g unit increase in Mn was found to be associated with a 1.80-fold increase (95% confidence interval: 1.37–2.82) in attention score, and a 1.46-fold increase (95% confidence interval: 1.01–1.74) in the rule breaking score. Thought score was not significantly associated with Mn concentration (p = 0.13) but was significantly lower in boys (p = 0.004). Conclusions: Exceeding Mn levels is potentially toxic and has been identified to be associated with worse externalized children’s behavioural health and emotional well-being. Future studies are necessary to find the exposure paths so that advice shall be provided to family and care providers in public health and environmental protection.

Altered Blood Brain Barrier Permeability and Oxidative Stress in Cntnap2 Knockout Rat Model

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by three core symptoms, specifically impaired social behavior, stereotypic/repetitive behaviors, and sensory/communication deficits. Although the exact pathophysiology of ASD is still unknown, host genetics, oxidative stress, and compromised blood brain barrier (BBB) have been implicated in predisposition to ASD. With regards to genetics, mutations in the genes such as CNTNAP2 have been associated with increased susceptibility of developing ASD. Although some studies observed conflicting results suggesting no association of CNTNAP2 with ASD, other investigations correlated this gene with autism. In addition, CNTNAP2 mediated signaling is generally considered to play a role in neurological disorders due to its critical role in neurodevelopment, neurotransmission, and synaptic plasticity. In this investigation, we studied BBB integrity and oxidative stress in Cntnap2^−/− rats. We observed that the BBB permeability was significantly increased in Cntnap2^−/− rats compared to littermate wild-type (WT) animals as determined by FITC-dextran and Evans blue assay. High levels of thiobarbituric acid reactive substances and lower amounts of reduced glutathione were observed in brain homogenates of Cntnap2^−/− rats, suggesting oxidative stress. Brain sections from Cntnap2^−/− rats showed intense inducible nitric oxide synthase immunostaining, which was undetectable in WT animals. Quantification of nitric oxide in brain homogenates revealed significantly high levels in Cntnap2^−/− rats compared to the control group. As increased permeability of the BBB and oxidative stress have been observed in ASD individuals, our results suggest that Cntnap2^−/− rats have a high construct and face validity and can be explored to develop effective therapeutic modalities.

Parental Occupational Exposure and Neurodevelopmental Disorders in Offspring: a Systematic Review and Meta-analysis

PURPOSE OF REVIEW

Parental occupational exposures might be associated with neurodevelopmental disorders (NDDs) in offspring. We aimed to conduct a systematic review and meta-analysis to summarize and synthesize the current literature and to estimate the pooled magnitude of the underlying association(s) between parental occupational exposures and subsequent risk of NDDs.

RECENT FINDINGS

In the meta-analysis of 20 included studies, significant associations were found between parental occupational exposure to pesticides or solvents and the risk of attention deficit hyperactivity disorder in offspring. Prenatal occupational exposure to pesticides was significantly associated with motor development or cognition disorders in children. Furthermore, some evidence showed that metals might have a role in the development of autism spectrum disorders. Further studies need to identify the level of parental occupational exposures that can be significantly associated with NDDs. Moreover, utilizing standardized outcome and exposure scales is recommended to incorporate paternal, maternal, and parental as well as both prenatal and postnatal exposure in future studies.

Prenatal Exposure to Metals and Neurodevelopment in Infants at Six Months: Rio Birth Cohort Study of Environmental Exposure and Childhood Development (PIPA Project)

The PIPA Project is a prospective birth cohort study based in Rio de Janeiro, Brazil, whose pilot study was carried out between October 2017 and August 2018. Arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg) concentrations were determined in maternal (n = 49) and umbilical cord blood (n = 46). The Denver Developmental Screening Test II (DDST-II) was applied in 50 six-month-old infants. Metals were detected in 100% of the mother and newborn samples above the limits of detection. Maternal blood lead concentrations were higher in premature newborns (GM: 5.72 µg/dL; p = 0.05). One-third of the infants (n = 17–35.4%) exhibited at least one fail in the neurodevelopment evaluation (fail group). Maternal blood arsenic concentrations were significantly (p = 0.03) higher in the “fail group” (GM: 11.85 µg/L) compared to infants who did not fail (not fail group) (GM: 8.47 µg/L). Maternal and umbilical cord blood arsenic concentrations were higher in all Denver Test’s domains in the “fail group”, albeit non-statistically significant, showing a tendency for the gross motor domain and maternal blood (p = 0.07). These findings indicate the need to further investigate the toxic effects of prenatal exposure to metals on infant neurodevelopment.

The combined effects of nucleotide-binding domain-like receptor protein 3 polymorphisms and levels of blood lead on developmental delays in preschool children

Nucleotide-binding domain-like receptors protein 3 (NLRP3) inflammasomes are associated with neuroinflammation and multiple NLRP3 genes regulate NLRP3 expression. Our study aimed to investigate the association of NLRP3 polymorphisms with developmental delay in preschool children. We also explored whether NLRP3 polymorphisms modified the effects of total urinary arsenic and blood cadmium and lead to developmental delays. A total of 178 children with developmental delays and 88 healthy children were analyzed for urinary arsenic concentrations and red blood cell lead and cadmium concentrations. We examined the genotypes of fifteen common single-nucleotide polymorphisms in NLRP3. We observed that levels of total urinary arsenic and blood lead were significantly associated with developmental delay. The NLRP3rs10754555 CG versus CC/GG, NLRP3rs12048215 AG versus AA/GG, and NLRP3rs12137901 TC/TT versus CC genotype showed a lower odds of developmental delay, with the odds ratio (OR) and 95% confidence interval (CI) = 0.38 (0.19-0.75), 0.52 (0.27-0.99), and 0.33 (0.12-0.90), respectively. Children with the NLRP3rs10754555 CC/GG genotype and high blood lead levels had a significant multiplicative interaction with developmental delay [OR (95% CI) = 9.74 (3.59-26.45)]. This study found evidence that suggested the joint effects of NLRP3rs10754555 CC/GG genotype and high blood lead levels on developmental delays.

Early-life lead exposure induces long-term toxicity in the central nervous system: From zebrafish larvae to juveniles and adults

Lead induced neurotoxicity has been extensively investigated. However, the potential connections between early-life lead exposure and the frequently observed aberrant neurobehavior in juveniles and adults remain unclear. In this study, zebrafish model was used to explore the immediate and long-term effects of early-life exposure to environmental levels of lead on the central nervous system, and the cellular and molecular mechanisms underlying the consequent abnormal neurobehavior. Lead exposed zebrafish larvae exhibited neurologic damage and defective neurobehavior. Consistent with clinical studies, despite being raised in lead-free conditions, the juvenile and adult fish experienced lead exposure earlier, presented ADHD-like symptoms, and the adult fish exhibited remarkably affected vitality and shoaling behavior. Their anxiety levels were elevated, whereas their social interaction, as well as learning and memory were strongly depressed. The expression profiles of key genes involved in neurodevelopment and neurotransmitter systems were significantly modulated, in similar patterns as in the larval stage. Notably, the density of neurons was decreased and varicosities in neuronal axons were frequently observed in the lead-exposed groups. It's tempting to speculate that the disruption of early neurodevelopment as well as the prolonged modulation of neuromorphic and neurotransmitter systems contribute to the lead-induced neurobehavioral disorders observed in juveniles and adulthood.

Increased serum levels of cadmium are associated with an elevated risk of cardiovascular disease in adults

Previous studies have determined the effects of exposure to certain heavy metals on cardiovascular disease (CVD); however, the association between cadmium exposure and CVD in adults remains unclear. The relationship between serum levels of cadmium and the risk of CVD was studied by analyzing available data from 38,223 different participants of the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2016. After adjusting for all covariates, we found that higher serum cadmium concentrations were positively related to both the overall risk of CVD (odds ratio (OR): 1.45; 95% confidence interval (CI): 1.22, 1.72; p for trend <0.001) and the risks of its subtypes, including congestive heart failure, coronary heart disease, heart attack, and stroke. Elevated cadmium levels were associated with increased levels of lipids and inflammatory factors, including blood triglycerides, total cholesterol, white blood cells (WBCs), and C-reactive protein (CRP). Our study provided epidemiological evidence that cadmium may increase the risk of CVD by elevating blood lipids and inflammation.

Childhood exposure to metal(loid)s in industrial and urban areas along the Persian Gulf using toenail tissue as a biomarker

Metal(loid)s (MLs) with natural or anthropogenic sources may cause adverse health effects in children. This study aimed to compare the childhood exposure to ΣMLs (essential, non-essential and toxic) in an industrial and an urban area in Southwest Iran using toenail tissue as a biomarker. The present study was carried out with school children in the age range of 7-12 years, who were living in an industrial area in the petrochemical and gas area (PGA) of the Central District of Asaluyeh County and in an urban area (UA) located in the Kaki District. A total of 270 boys and girls were recruited in January to April 2019. The ICP-MS was used for determination of the studied MLs. A multi-linear regression model was constructed to assess the effect of residence area on toenail ML levels. A significantly higher level of ΣMLs in toenail from the PGA was observed compared to the level in the UA (8.839 vs. 7.081 μg/g, β = -0.169 and p < 0.05). However, all of the 15 MLs studied were detected in the toenail samples from both study sites. Significant differences for the mean Cr (β = -0.563), Fe (β = -0.968), Mn (β = -0.501), Ni (β = -0.306), and Pb (β = -0.377) levels were found between toenail samples from the study areas (p < 0.05), with higher levels in the PGA. The results of this study suggest that children in industrial area are prone to a greater risk for ML exposures compared with those living in a non-industrial urban area.

Brain dysfunction in tubular and tubulointerstitial kidney diseases

Kidney function has two important elements: glomerular filtration and tubular function (secretion and reabsorption). A persistent decrease in glomerular filtration rate (GFR), with or without proteinuria, is diagnostic of chronic kidney disease (CKD). While glomerular injury or disease is a major cause of CKD and usually associated with proteinuria, predominant tubular injury, with or without tubulointerstitial disease, is typically non-proteinuric. CKD has been linked with cognitive impairment, but it is unclear how much this depends on a reduced GFR, altered tubular function or the presence of proteinuria. Since CKD is often accompanied by tubular and interstitial dysfunction, we explore here for the first time the potential role of the tubular and tubulointerstitial compartments in cognitive dysfunction. To help address this issue, we have selected a group of primary tubular diseases with preserved GFR, in which to review the evidence for any association with brain dysfunction. Cognition, mood, neurosensory, and motor disturbances are not well characterized in tubular diseases, possibly because they are subclinical and less prominent than other clinical manifestations. The available literature suggests that brain dysfunction in tubular and tubulointerstitial diseases is usually mild and is more often seen in disorders of water handling. Brain dysfunction may occur when severe electrolyte and water disorders in young children persist over a long period of time before the diagnosis is made. We have chosen as examples to highlight this topic, Bartter and Gitelman syndromes and nephrogenic diabetes insipidus. We discuss current published findings, some unanswered questions, and propose topics for future research.

Exposure to lead on expression levels of brain immunoglobulins, inflammatory cytokines, and brain-derived neurotropic factor in fetal and postnatal mice with autism-like characteristics

Autism spectrum disorders (ASD) are neurodevelopmental disorders, and their incidence is increasing worldwide. Increased exposure to environmental metal lead (Pb) has been proposed as a risk factor associated with ASD. In the present study, BTBR T+ tf/J (BTBR) mice with ASD-like behavioral characteristics and control FVB mice were exposed gestationally and/or neonatally to Pb, and compared with highly social FVB mice to investigate neuroimmunological abnormalities. IgG1 and IgG2a levels in fetal brains from BTBR dams exposed to Pb (BTBR-Pb) were significantly higher than those of BTBR-controls (BTBR-C). However, this change did not occur in FVB mice exposed to Pb. The IgG1:IgG2a ratio was higher in both fetal and postnatal brains of BTBR mice compared to FVB animals regardless of Pb exposure. The IL-4:IFN-γ ratio was elevated in BTBR-Pb relative to BTBR-C mice, but this ratio was not markedly affected following Pb exposure in FVB animals. These findings suggest the potential for a Pb-driven predominant T_H2-like reactivity profile in brain microenvironment present in BTBR mice. Brain-derived neurotrophic factor was decreased in fetal and postnatal BTBR-Pb brains relative to BTBR-C brains but not in FVB-Pb relative to FVB-C mice. Taken together, data demonstrate that Pb exposure might contribute to developmental brain abnormalities associated with ASD, particularly in individuals with genetic susceptibility to ASD.

ERK/MAPK signalling in the developing brain: Perturbations and consequences

The extracellular regulated kinase/microtubule-associated protein kinase (ERK/MAPK) signalling pathway transduces signals that cause an alteration in the ongoing metabolic pathways and modifies gene expression patterns; thus, influencing cellular behaviour. ERK/MAPK signalling is essential for the proper development of the nervous system from neural progenitor cells derived from the embryonic mesoderm. Several signalling molecules that regulate the well-coordinated process of neurodevelopment transduce developmental information through the ERK/MAPK signalling pathway. The ERK/MAPK is a potential novel therapeutic target in several neurodevelopmental disorders, however, despite years of study, there is still significant uncertainty about the exact mechanism by which the ERK/MAPK signalling pathway elicits specific responses in neurodevelopment. Here, we will review the evidence highlighting the role of ERK/MAPK signalling in neurodevelopment. We will also discuss the structural implication and behavioural deficits associated with perturbed ERK/MAPK signalling pathway in cortical development, whilst examining its contribution to the neuropathology of several neurodevelopmental disorders, such as Autism Spectrum Disorder, Schizophrenia, Fragile X, and Attention Deficit Hyperactive Disorder.

Neurodevelopmental Disorders (NDD) Caused by Genomic Alterations of the Ubiquitin-Proteasome System (UPS): the Possible Contribution of Immune Dysregulation to Disease Pathogenesis

Over thirty years have passed since the first description of ubiquitin-positive structures in the brain of patients suffering from Alzheimer’s disease. Meanwhile, the intracellular accumulation of ubiquitin-modified insoluble protein aggregates has become an indisputable hallmark of neurodegeneration. However, the role of ubiquitin and a fortiori the ubiquitin-proteasome system (UPS) in the pathogenesis of neurodevelopmental disorders (NDD) is much less described. In this article, we review all reported monogenic forms of NDD caused by lesions in genes coding for any component of the UPS including ubiquitin-activating (E1), -conjugating (E2) enzymes, ubiquitin ligases (E3), ubiquitin hydrolases, and ubiquitin-like modifiers as well as proteasome subunits. Strikingly, our analysis revealed that a vast majority of these proteins have a described function in the negative regulation of the innate immune response. In this work, we hypothesize a possible involvement of autoinflammation in NDD pathogenesis. Herein, we discuss the parallels between immune dysregulation and neurodevelopment with the aim at improving our understanding the biology of NDD and providing knowledge required for the design of novel therapeutic strategies.

Perturbed MAPK signaling in ASD: Impact of metal neurotoxicity

The mitogen-activated protein kinase (MAPK) pathways are intracellular signaling pathways necessary for regulating various physiological processes, including neurodevelopment. The developing brain is vulnerable to toxic substances, and metals, such as lead, mercury, nickel, manganese, and others, have been proven to induce disturbances in the MAPK signaling pathway. Since a well-regulated MAPK is necessary for normal neurodevelopment, perturbation of the MAPK pathway results in neurodevelopmental disorders, including autism spectrum disorder (ASD). ASD affects brain parts responsible for communication, cognition, social interaction, and other patterned behaviors. Several studies have addressed the role of metals in the etiopathogenesis of ASD. Here, we briefly review the MAPK signaling pathway and its role in neurodevelopment. Furthermore, we highlight the role of metal toxicity in the development of ASD and how perturbed MAPK signaling may result in ASD.

Prenatal Folic Acid Supplements and Offspring’s Autism Spectrum Disorder: A Meta-analysis and Meta-regression

We systematically reviewed the evidence on the association between maternal folic acid supplementation and the risk of offspring’s autism spectrum disorders (ASD). A total of 10 studies with 23 sub-studies (9795 ASD cases) were included. Folic acid supplementation during early pregnancy was associated with a lower risk of offspring’s ASD [OR 0.57, 95% CI 0.41–0.78]. The consumption of a daily amount of at least 400 μg folic acid from dietary sources and supplements, was associated with a reduced risk of offspring ASD [OR 0.55, 95% CI 0.36–0.83]. Critical effective maternal folic acid supplementation strategies, such as intake timing and intake dosage, may aid the reduction in the risk of offspring ASD. This meta-analysis provided new insights for the prevention of offspring’s ASD.

Neuroprotective Effects of Quercetin in Pediatric Neurological Diseases

Oxidative stress is a crucial event underlying several pediatric neurological diseases, such as the central nervous system (CNS) tumors, autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). Neuroprotective therapy with natural compounds used as antioxidants has the potential to delay, ameliorate or prevent several pediatric neurological diseases. The present review provides an overview of the most recent research outcomes following quercetin treatment for CNS tumors, ASD and ADHD as well as describes the potential in vitro and in vivo ameliorative effect on oxidative stress of bioactive natural compounds, which seems like a promising future therapy for these diseases. The neuroprotective effects of quercetin against oxidative stress can also be applied in the management of several neurodegenerative disorders with effects such as anti-cancer, anti-inflammatory, anti-viral, anti-obesity and anti-microbial. Therefore, quercetin appears to be a suitable adjuvant for therapy against pediatric neurological diseases.