High levels of homocysteine and low serum paraoxonase 1 arylesterase activity in children with autism

Alterations in Antioxidant Status and Erythrocyte Properties in Children with Autism Spectrum Disorder

Erythrocytes are responsible for the transport of oxygen within the organism, which is particularly important for nerve tissues. Erythrocyte quality has been shown to be deteriorated in oxidative stress conditions. In this study, we measured the same series of oxidative stress markers in plasma and erythrocytes to compare the differences between neurotypical children (controls) and children with autism spectrum disorder (ASD). We also focused on erythrocyte properties including their deformability, osmotic resistance, Na,K-ATPase activity, nitric oxide levels and free radical levels in children with ASD and controls. Greater oxidative damage to proteins and lipids was observed in the erythrocytes than in the plasma of ASD subjects. Additionally, antioxidant enzymes were more active in plasma samples from ASD children than in their erythrocytes. Significantly higher nitric oxide level and Na,K-ATPase enzyme activity were detected in erythrocytes of ASD individuals in comparison with the controls. Changes in oxidative status could at least partially contribute to the deterioration of erythrocyte morphology, as more frequent echinocyte formation was detected in ASD individuals. These alterations are most probably responsible for worsening the erythrocyte deformability observed in children with ASD. We can conclude that abnormalities in antioxidant status and erythrocyte properties could be involved in the pathomechanisms of ASD and eventually contribute to its clinical manifestations.

Dietary pattern in autism increases the need for probiotic supplementation: A comprehensive narrative and systematic review on oxidative stress hypothesis

Autism spectrum disorders (ASDs) are associated with specific dietary habits, including limited food selection and gastrointestinal problems, resulting in an altered gut microbiota. Autistic patients have an elevated abundance of certain gut bacteria associated with increased oxidative stress in the gastrointestinal tract. Probiotic supplementation has been shown to decrease oxidative stress in a simulated gut model, but the antioxidant effects of probiotics on the oxidative stress of the gut in autistic patients have not been directly studied. However, it is speculated that probiotic supplementation may help decrease oxidative stress in the gastrointestinal tract of autistic patients due to their specific dietary habits altering the microbiota. PubMed, Scopus and Web of Science databases and Google Scholar were searched up to May 2023. This systematic-narrative review aims to present the latest evidence regarding the changes in eating habits of autistic children which may further increase the gut microbiota induced oxidative stress. Additionally, this review will assess the available literature on the effects of probiotic supplementation on oxidative stress parameters.

Folate in maternal rheumatoid arthritis-filial autism spectrum disorder continuum

Rheumatoid Arthritis (RA) is an inflammatory autoimmune disease that affects women three times more than men. Epidemiological studies found that the incidence of Autism Spectrum Disorder (ASD), a neurological and developmental disorder, in children born to mothers suffering from RA is higher compared with the control population. Considering that the pathogenesis of ASD could be traced back to pregnancy and in uterine conditions, and the evidence of reduced folate levels in the brain of ASD-affected children, we aimed to study the role of folate, as an important nutritional factor during pregnancy, in associating maternal RA to ASD development in the offspring. Folate balance during RA could be influenced twice, initially during the immune activation associated with disease onset, and later during the treatment with anti-folate drugs, with a potential consequence of folate deficiency. Maternal folate deficiency during pregnancy could increase homocysteine levels, oxidative stress, and global DNA hypomethylation, all known risk factors in ASD pathogenesis. These effects could be intensified by genetic polymorphisms in the folate system, which were also found as genetic risk factors for both RA and ASD. The available evidence suggests that folate level as an important factor during RA, pregnancy and ASD could have pathological and therapeutical significance and should be carefully monitored and investigated in the RA-pregnancy-ASD axis.

Amino Acids, B Vitamins, and Choline May Independently and Collaboratively Influence the Incidence and Core Symptoms of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a developmental disorder of variable severity, characterized by difficulties in social interaction, communication, and restricted or repetitive patterns of thought and behavior. In 2018, the incidence of ASD was 2.4 times higher than estimated in 2000. Behavior and brain development abnormalities are present in the complex disorder of ASD. Nutritional status plays a key role in the incidence and severity of the core symptoms of ASD. The aim of this study was to review the available peer-reviewed studies that evaluated the relationship between amino acids, choline, B vitamins, and ASD incidence and/or severity of symptoms. Through examining plasma profiles, urine samples, and dietary intake, researchers found that low choline, abnormal amino acid, and low B vitamin levels were present in children with ASD compared to those without ASD. The evidence supports the need for future research that implements simultaneous supplementation of all essential nutrients in individuals with ASD and among prenatal mothers. Future evidence could lead to scientific breakthroughs, ultimately reducing the rates of ASD incidence and severity of symptoms by applying nutritional interventions in at-risk populations.

Improvement of the Clinical and Psychological Profile of Patients with Autism after Methylcobalamin Syrup Administration

(1) Background: Autism, also known as autism-spectrum disorder, is a pervasive developmental disorder affecting social skills and psychological status in particular. The complex etiopathogenesis of autism limits efficient therapy, which leads to problems with the normal social integration of the individual and causes severe family distress. Injectable methylcobalamin was shown to improve the clinical status of patients via enhanced cell oxidative status and/or methylation capacity. Here we tested the efficiency of a syrup form of methylcobalamin in treating autism. (2) Methods: Methylcobalamin was administered daily at 500 µg dose to autistic children and young adults (n = 25) during a 200-day period. Clinical and psychological status was evaluated by parents and psychologists and plasma levels of reduced and oxidized glutathione, vitamin B12, homocysteine, and cysteine were determined before the treatment, and at day 100 and day 200 of the treatment. (3) Results: Good patient compliance was reported. Methylcobalamin treatment gradually improved the overall clinical and psychological status, with the highest impact in the social domain, followed by the cognitive, behavioral and communication characteristics. Changes in the clinical and psychological status were strongly associated with the changes in the level of reduced glutathione and reduced/oxidized glutathione ratio. (4) Conclusion: A high dose of methylcobalamin administered in syrup form ameliorates the clinical and psychological status of autistic individuals, probably due to the improved oxidative status.

Vascular inflammation and impaired reverse cholesterol transport and lipid metabolism in obese children and adolescents

BACKGROUND AND AIMS

Childhood obesity is associated to complications such as insulin resistance and dyslipidemia. High density lipoproteins (HDL) constitute the only lipoprotein fraction with ateroprotective properties. The aim of the present study was to analyze inflammatory markers, carbohydrate metabolism, lipid profile and HDL functionality in obese children and adolescents compared to healthy controls.

METHODS AND RESULTS

Twenty obese children and adolescents (Body mass index z score >3.0) (9-15 years old) and 20 age and sex similar controls were included in the study. Triglyceride (TG), total cholesterol (TC), HDL-C, LDL-C, apolipoproteins (apo) A-I and B, glucose and insulin levels were quantified. Lipid indexes and HOMA-IR were calculated. Cholesterol efflux (CEC), lipoprotein associated phospholipase A₂ (Lp-PLA₂), lecithin-cholesterol acyl transferase (LCAT) and cholesteryl ester transfer protein, plus paraoxonase and arylesterase (ARE) activities were evaluated. Obese children and adolescents showed significantly higher TG [69 (45-95) vs 96 (76-121); p < 0.05], non-HDL-C [99 ± 34 vs 128 ± 26; p < 0.01], TC/HDL-C [2.8 ± 0.6 vs 4.7 ± 1.5; p < 0.01], TG/HDL-C [1.1 (1.0-1.8) vs 2,2 (1.4-3.2); p < 0.01], and HOMA-IR [1.5 (1.1-1.9) vs. 2.6 (2.0-4.5); p < 0.01] values, plus Lp-PLA₂ activity [8.3 ± 1.9 vs 7.1 ± 1.7 umol/ml.h; p < 0,05] in addition to lower HDL-C [57 ± 10 vs 39 ± 9; p < 0.01], apo A-I [143 ± 25 vs 125 ± 19; p < 0.05], and CEC [6.4 (5.1-6.8) vs. 7.8 (5.7-9.5); p < 0.01] plus LCAT [12.6 ± 3.3 vs 18.7 ± 2.6; p < 0.05] and ARE [96 ± 19 vs. 110 ± 19; p < 0.05] activities. Lp-PLA₂ activity correlated with LDL-C (r = 0.72,p < 0.01), non-HDL-C (r = 0.76,p < 0.01), and apo B (r = 0.60,p < 0.01). LCAT activity correlated with triglycerides (r = -0.78,p < 0.01), HDL-C (r = 0.64,p < 0.01), and apo A-I (r = 0.62, p < 0.05). ARE activity correlated with HDL-C (r = 0.32,p < 0.05) and apoA-I (r = 0.43,p < 0.01). CEC was negatively associated with BMI z-score (r = -0.36,p < 0.05), and triglycerides (r = -0.28,p < 0.05), and positively with LCAT activity (r = 0.65,p < 0.05). In multivariate analysis, BMI z-score was the only parameter significantly associated to CEC (r2 = 0.43, beta = -0.38, p < 0.05).

CONCLUSION

The obese group showed alterations in carbohydrate and lipid metabolism, which were associated to the presence of vascular specific inflammation and impairment of HDL atheroprotective capacity. These children and adolescents would present qualitative alterations in their lipoproteins which would determine higher risk of suffering premature cardiovascular disease.

Oxidative Stress in Autism Spectrum Disorder-Current Progress of Mechanisms and Biomarkers

Autism spectrum disorder (ASD) is a type of neurodevelopmental disorder that has been diagnosed in an increasing number of children around the world. Existing data suggest that early diagnosis and intervention can improve ASD outcomes. However, the causes of ASD remain complex and unclear, and there are currently no clinical biomarkers for autism spectrum disorder. More mechanisms and biomarkers of autism have been found with the development of advanced technology such as mass spectrometry. Many recent studies have found a link between ASD and elevated oxidative stress, which may play a role in its development. ASD is caused by oxidative stress in several ways, including protein post-translational changes (e.g., carbonylation), abnormal metabolism (e.g., lipid peroxidation), and toxic buildup [e.g., reactive oxygen species (ROS)]. To detect elevated oxidative stress in ASD, various biomarkers have been developed and employed. This article summarizes recent studies about the mechanisms and biomarkers of oxidative stress. Potential biomarkers identified in this study could be used for early diagnosis and evaluation of ASD intervention, as well as to inform and target ASD pharmacological or nutritional treatment interventions.

Analysis of association between components of the folate metabolic pathway and autism spectrum disorder in eastern Indian subjects

BACKGROUND

Folate has a pivotal role in maintaining different cellular processes including DNA integrity and neurotransmitter levels. Further, folate deficiency was reported in subjects with neuropsychiatric disorders including autism spectrum disorder (ASD).

METHODS AND RESULTS

We recruited ASD probands following the Diagnostic and Statistical Manual of Mental Disorder-IV/-5. Severity was assessed by the Childhood Autism Rating Scale2-Standard Test (CARS2-ST). Functional SNPs in reduced folate carrier1 (rs1051266), methylenetetrahydrofolate dehydrogenase (rs2236225), methylenetetrahydrofolate methyltransferase (rs1805087), methylenetetrahydrofolate reductase (rs1801133 and rs1801131), cystathionine-beta- synthase (rs5742905), and serine hydroxymethyltransferase (rs1979277) genes were analyzed in the ASD probands (N = 203), their parents and controls (N = 250) by PCR/TaqMan based methods. Plasma homocysteine and vitamin B12 levels were examined by Enzyme-Linked ImmunoSorbent Assay. Statistical analysis revealed higher frequencies of rs1051266 and rs1805087 "A" alleles (P = 8.233e-005 and P = 0.010 respectively) and rs1051266 "AA" genotype (P = 0.02) in the ASD probands. Gender based stratified analysis revealed higher frequency of rs1051266 "AA" in the male probands (P = 0.001) while frequencies of rs1805087 "A" (P = 0.001) and "AA" (P < 0.05), and rs2236225 "CC" (P = 0.03) were higher in the females. The case-control analysis also exhibited a significant difference in the occurrence of biallelic and triallelic haplotypes. rs1051266 "A", rs1979277 "T" and rs5742905 "C" alleles showed biased parental transmission (P = 0.02). CARS2-ST scores were higher in the presence of rs5742905 "T" while scores were lower in the presence of rs1979277 "T" and rs1051266 "A". ASD probands showed vitamin B12 deficiency.

CONCLUSION

Based on these observations, we infer that components needed for proper folate metabolism may influence ASD severity in this population.

Alterations in Gut Vitamin and Amino Acid Metabolism are Associated with Symptoms and Neurodevelopment in Children with Autism Spectrum Disorder

Metabolic disturbance may be implicated in the pathogenesis of autism. This study aimed to investigate the gut metabolomic profiles of autistic children and to analyze potential interaction between gut metabolites with autistic symptoms and neurodevelopment levels. We involved 120 autistic and 60 neurotypical children. Autistic symptoms and neurodevelopment levels were assessed. Fecal samples were analyzed using untargeted liquid chromatography-tandem mass spectrometry methods. Our results showed the metabolic disturbances of autistic children involved in multiple vitamin and amino acid metabolism pathways, with the strongest enrichment identified for tryptophan metabolism, retinol metabolism, cysteine-methionine metabolism, and vitamin digestion and absorption. Differential gut metabolites were correlated to autistic symptoms and neurodevelopment levels. Our findings improved the understanding of the perturbations of metabolome networks in autism.

Sulfur amino acid metabolism and related metabotypes of autism spectrum disorder: A review of biochemical evidence for a hypothesis

There are multiple lines of evidence for an impaired sulfur amino acid (SAA) metabolism in autism spectrum disorder (ASD). For instance, the concentrations of methionine, cysteine and S-adenosylmethionine (SAM) in body fluids of individuals with ASD is significantly lower while the concentration of S-adenosylhomocysteine (SAH) is significantly higher as compared to healthy individuals. Reduced methionine and SAM may reflect impaired remethylation pathway whereas increased SAH may reflect reduced S-adenosylhomocysteine hydrolase activity in the catabolic direction. Reduced SAM/SAH ratio reflects an impaired methylation capacity. We hypothesize multiple mechanisms to explain how the interplay of oxidative stress, neuroinflammation, mercury exposure, maternal use of valproate, altered gut microbiome and certain genetic variants may lead to these SAA metabotypes. Furthermore, we also propose a number of mechanisms to explain the metabolic consequences of abnormal SAA metabotypes. For instance in the brain, reduced SAM/SAH ratio will result in melatonin deficiency and hypomethylation of a number of biomolecules such as DNA, RNA and histones. In addition to previously proposed mechanisms, we propose that impaired activity of "radical SAM" enzymes will result in reduced endogenous lipoic acid synthesis, reduced molybdenum cofactor synthesis and impaired porphyrin metabolism leading to mitochondrial dysfunction, porphyrinuria and impaired sulfation capacity. Furthermore depletion of SAM may also lead to the disturbed mTOR signaling pathway in a subgroup of ASD. The proposed "SAM-depletion hypothesis" is an inclusive model to explain the relationship between heterogeneous risk factors and metabotypes observed in a subset of children with ASD.

Reevaluation of Serum Arylesterase Activity in Neurodevelopmental Disorders

Organophosphate compounds (OPs) interfere with neurodevelopment and are neurotoxic for humans and animals. They are first biotransformed to the more toxic oxon form, and then hydrolyzed to specific metabolites by the enzyme paraoxonase/arylesterase, encoded by the gene PON1 located on human chr. 7q21.3. In autism spectrum disorder (ASD) and in attention-deficit/hyperactivity disorder (ADHD), a correlation between OP exposure and disease onset has been reported. In this case-control study, we aimed to replicate our previous work showing reduced levels of serum PON1 arylesterase activity in Italian and Caucasian-American ASD samples, and to extend our analysis to other neurodevelopmental disorders, namely ADHD and developmental language disorder (DLD), also known as specific language impairment (SLI). The arylesterase activity, measured using standard spectrophotometric methods, is significantly reduced in the ADHD, and not in the ASD sample compared with the controls. Our previous results seemingly stem from spuriously high arylesterase levels in the former control sample. Finally, genotyping SNPs rs705379 and rs662 using TDI-FP, a significant effect of rs705379 alleles on the serum arylesterase activity is observed in all of the subgroups tested, regardless of diagnosis, as well as a lack of association between PON1 gene polymorphisms and ASD/ADHD susceptibility in the Italian population. In summary, the serum arylesterase activity is reduced in children and adolescents with ADHD, and this reduction is not due to the functional PON1 gene variants assessed in this study. Based on previous literature, it may more likely reflect enhanced oxidative stress than specific genetic underpinnings.

Association Study of MTHFR C677T Polymorphism and Birth Body Mass With Risk of Autism in Chinese Han Population

Objective: To explore the association of the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism with birth body mass and risk of autism in Chinese Han population. Methods: A total 1,505 Chinese Han autism patients were recruited, using the Diagnostic and Statistical Manual of Mental Disorders, 4th revised version (DSM-IV-R) diagnostic criteria for autism, and 1,308 sex-matched healthy controls were also enrolled for the study. All the participants' birth body masses were counted according to the medical records. The MTHFR C677T genotypes were detected using the polymerase chain reaction-restrict fragment length polymorphism (PCR-RFLP) method. The association between C677T polymorphism, birth body mass, and risk of autism were analyzed using the chi-square tests. Results: The present study found that the MTHFR 677T was significantly associated with risk of autism [P = 0.004, odds ratio (OR) = 1.18, 95% CI = 1.02-1.29). The autism children more frequently showed low birth body mass (<2.5 kg) than healthy control subjects (8.6 vs. 5.3%, P = 0.001, OR = 1.67, 95% CI = 1.24-2.26). The interactive effects between MTHFR 677T and low birth body mass (P = 0.0001, OR = 2.18, 95% CI = 1.44-3.32) were also significantly associated with risk of autism. Conclusions: The MTHFR C677T polymorphism and low birth body mass may be associated with risk of autism in Chinese Han population.

High KEAP1, NRF2 and Low HO-1 Serum Levels in Children with Autism

Introduction

The purpose of our study was to investigate heme oxygenase-1 (HO-1), nuclear factor erythroid-2-related factor 2 (NRF2), and kelch-like ECH-associated protein 1 (KEAP1) levels in children with autism spectrum disorder (ASD) and to reveal their association with the severity of autism.

Methods

This study measured serum HO-1, KEAP1, and NRF2 levels in 43 patients with ASD (aged 3-12 years) and in 41 age- and gender-matched healthy controls. ASD severity was rated using the Childhood Autism Rating Scale (CARS). HO-1, KEAP1, and NRF2 levels were determined in the biochemistry laboratory using the ELISA technique.

Results

HO-1 levels were significantly lower in patients aged 3-12 years compared to controls aged 3-12, while KEAP1 and NRF2 levels were significantly higher (p=0.020, p<0.001, and p=0.017, respectively). No correlation was determined between ASD severity on the basis of total CARS scores and HO-1, KEAP1 or NRF2 (p>0.05).

Conclusion

This study suggests that oxidative stress is higher in children with ASD and that HO-1 levels are insufficient to achieve oxidative balance.

The role of glutathione redox imbalance in autism spectrum disorder: A review

The role of glutathione in autism spectrum disorder (ASD) is emerging as a major topic, due to its role in the maintenance of the intracellular redox balance. Several studies have implicated glutathione redox imbalance as a leading factor in ASD, and both ASD and many other neurodevelopmental disorders involve low levels of reduced glutathione (GSH), high levels of oxidized glutathione (GSSG), and abnormalities in the expressions of glutathione-related enzymes in the blood or brain. Glutathione metabolism, through its impact on redox environment or redox-independent mechanisms, interferes with multiple mechanisms involved in ASD pathogenesis. Glutathione-mediated regulation of glutamate receptors [e.g., N-methyl-d-aspartate (NMDA) receptor], as well as the role of glutamate as a substrate for glutathione synthesis, may be involved in the regulation of glutamate excitotoxicity. However, the interaction between glutathione and glutamate in the pathogenesis of brain diseases may vary from synergism to antagonism. Modulation of glutathione is also associated with regulation of redox-sensitive transcription factors nuclear factor kappa B (NF-κB) and activator protein 1 (AP-1) and downstream signaling (proinflammatory cytokines and inducible enzymes), thus providing a significant impact on neuroinflammation. Mitochondrial dysfunction, as well as neuronal apoptosis, may also provide a significant link between glutathione metabolism and ASD. Furthermore, it has been recently highlighted that glutathione can affect and modulate DNA methylation and epigenetics. Review analysis including research studies meeting the required criteria for analysis showed statistically significant differences between the plasma GSH and GSSG levels as well as GSH:GSSG ratio in autistic patients compared with healthy individuals (P = 0.0145, P = 0.0150 and P = 0.0202, respectively). Therefore, the existing data provide a strong background on the role of the glutathione system in ASD pathogenesis. Future research is necessary to investigate the role of glutathione redox signaling in ASD, which could potentially also lead to promising therapeutics.

Blood homocysteine levels in children with autism spectrum disorder: An updated systematic review and meta-analysis

Results of studies on peripheral blood levels of homocysteine (Hcy) in children with autism spectrum disorder (ASD) are inconsistent, and conclusions from two previous meta-analyses on this subject published in 2012 are already outdated. Therefore, we conducted an updated systematic review and meta-analysis to quantitatively summarize the peripheral blood Hcy data in children with ASD compared with healthy controls (HC). We searched PubMed, EMBASE, PsycINFO, PsycARTICLES, Web of Science, and Cochrane Library databases from inception to September 2019 for eligible studies, with no language restriction. Using random-effects model, we computed summary statistics. Thirty-one studies (3304 participants including 1641 cases) were included. The pooled results showed that the peripheral blood Hcy levels were significantly elevated in children with ASD when compared to HC (Hedges's g = 0.56, 95% CI = 0.36 to 0.76, P < 0.001). By sensitivity analyses, we confirmed that our results were quite robust. Additionally, no publication bias was observed in this meta-analysis. In conclusion, our study support the association of increased circulating Hcy levels with ASD in children, and the involvement of Hcy in the occurrence of ASD. However, in view of the significant between-study heterogeneity, the conclusions should be interpreted cautiously and more investigation is required.

Oxidative Stress in Autism Spectrum Disorder

According to the United States Centers for Disease Control and Prevention (CDC), as of July 11, 2016, the reported average incidence of children diagnosed with an autism spectrum disorder (ASD) was 1 in 68 (1.46%) among 8-year-old children born in 2004 and living within the 11 monitoring sites' surveillance areas in the United States of America (USA) in 2012. ASD is a multifaceted neurodevelopmental disorder that is also considered a hidden disability, as, for the most part; there are no apparent morphological differences between children with ASD and typically developing children. ASD is diagnosed based upon a triad of features including impairment in socialization, impairment in language, and repetitive and stereotypic behaviors. The increasing incidence of ASD in the pediatric population and the lack of successful curative therapies make ASD one of the most challenging disorders for medicine. ASD neurobiology is thought to be associated with oxidative stress, as shown by increased levels of reactive oxygen species and increased lipid peroxidation, as well as an increase in other indicators of oxidative stress. Children with ASD diagnosis are considered more vulnerable to oxidative stress because of their imbalance in intracellular and extracellular glutathione levels and decreased glutathione reserve capacity. Several studies have suggested that the redox imbalance and oxidative stress are integral parts of ASD pathophysiology. As such, early assessment and treatment of antioxidant status may result in a better prognosis as it could decrease the oxidative stress in the brain before it can induce more irreversible brain damage. In this review, many aspects of the role of oxidative stress in ASD are discussed, taking into account that the process of oxidative stress may be a target for therapeutic interventions.

Higher Levels of Low Molecular Weight Sulfur Compounds and Homocysteine Thiolactone in the Urine of Autistic Children

In this study, the levels of concentration of homocysteine thiolactone (HTL), cysteine (Cys), and cysteinylglycine (CysGly) in the urine of autistic and non-autistic children were investigated and compared. HTL has never been analyzed in autistic children. The levels of low molecular weight sulfur compounds in the urine of both groups were determined by validated methods based on high-performance liquid chromatography with spectrofluorometric and diode-array detectors. The statistical data show a significant difference between the examined groups. Children with autism were characterized by a significantly higher level of HTL (p = 5.86 × 10⁻⁸), Cys (p = 1.49 × 10⁻¹⁰) and CysGly (p = 1.06 × 10⁻⁸) in urine compared with the control group. A difference in the p-value of <0.05 is statistically significant. Higher levels of HTL, Cys, and CysGly in the urine of 41 children with autism, aged 3 to 17, were observed. The obtained results may indicate disturbances in the metabolism of methionine, Cys, and glutathione in some autistic patients. These preliminary results suggest that further research with more rigorous designs and a large number of subjects is needed.

Homocysteine: Its Possible Emerging Role in At-Risk Population Groups

Increased plasma homocysteine is a risk factor for several pathological disorders. The present review focused on the role of homocysteine (Hcy) in different population groups, especially in risk conditions (pregnancy, infancy, old age), and on its relevance as a marker or etiological factor of the diseases in these age groups, focusing on the nutritional treatment of elevated Hcy levels. In pregnancy, Hcy levels were investigated in relation to the increased risk of adverse pregnancy outcomes such as small size for gestational age at birth, preeclampsia, recurrent abortions, low birth weight, or intrauterine growth restriction. In pediatric populations, Hcy levels are important not only for cardiovascular disease, obesity, and renal disease, but the most interesting evidence concerns study of elevated levels of Hcy in autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD). Finally, a focus on the principal pathologies of the elderly (cardiovascular and neurodegenerative disease, osteoporosis and physical function) is presented. The metabolism of Hcy is influenced by B vitamins, and Hcy-lowering vitamin treatments have been proposed. However, clinical trials have not reached a consensus about the effectiveness of vitamin supplementation on the reduction of Hcy levels and improvement of pathological condition, especially in elderly patients with overt pathologies, suggesting that other dietary and non-dietary factors are involved in high Hcy levels. The importance of novel experimental designs focusing on intra-individual variability as a complement to the typical case-control experimental designs and the study of interactions between different factors it should be emphasized.

Frontocingulate Dysfunction Is Associated with Depression and Decreased Serum PON1 in Methamphetamine-Dependent Patients

INTRODUCTION

Studies have been reported that frequent use of methamphetamine (MA) is associated with brain function impairment, mood disorders and excessive free radical production accompanied by the decreased level of the antioxidant response elements, but no study investigated their correlations simultaneously. In the current study, the correlation of brain function, depression and anxiety levels, and the serum levels of PON1 (an antioxidant) in MA-dependent patients were investigated.

METHODS

Nineteen active MA abusers and 18 control subjects performed color-word Stroop task during fMRI and the state of their depression, anxiety, and stress were measured by the Depression, Anxiety and Stress Scale-21 Items (DASS-21) questionnaire. Their blood samples were collected to measure the level of PON1 by the human enzyme-linked immunosorbent assay (ELISA) kit and its correlation with the measured variables was studied.

RESULTS

Analysis of fMRI findings showed frontocingulate dysfunction in Stroop effect condition, including left anterior cingulate cortex, paracingulate gyrus, superior frontal gyrus, and frontal pole in MA-dependent patients, which was associated with a higher level of depression and decreased level of serum PON1 in these patients.

DISCUSSION

The results of the current study showed that MA-dependency is associated with frontocingulate dysfunction, decreased serum PON1 concentration, and increased depression/anxiety, which is worth to be more studied to elucidate their roles in the pathophysiology of MA addiction.

Importance of Nutrition Intervention in Autistic Patients

Along with the issues of inflated social and financial burden associated with autism spectrum disorder (ASD), specific treatment for this disorder has also not been developed. Having a thorough look at previous trials done to treat autism, we find that nutrition intervention had been used frequently as a complementary form of therapy. Indeed, an early diagnosis of nutrition deficiency and metabolic disorders done concomitantly with accurate therapeutic interventions can be a cornerstone for improving cognitive and behavioral aptitudes of people with autism. Several studies have showed that increasing the intake of specific nutrients can reduce the symptoms and comorbidities associated with autism. Consequently, nutrition intervention and appropriate supplementation can be crucial in managing and treating autism. This paper will discuss recent literature on the significance of metabolic aspects in autistic disorder and highlight the influence of nutrition intervention on the symptoms of autism.

An association study of severity of intellectual disability with peripheral biomarkers of disabled children in a rehabilitation home, Kolkata, India

The current investigation has identified the biomarkers associated with severity of disability and correlation among plethora of systemic, cellular and molecular parameters of intellectual disability (ID) in a rehabilitation home. The background of study lies with the recent clinical evidences which identified complications in ID. Various indicators from blood and peripheral system serve as potential surrogates for disability related changes in brain functions. ID subjects (Male, age 10 ± 5 yrs, N = 45) were classified as mild, moderate and severe according to the severity of disability using standard psychometric analysis. Clinical parameters including stress biomarkers, neurotransmitters, RBC morphology, expressions of inflammatory proteins and neurotrophic factor were estimated from PBMC, RBC and serum. The lipid peroxidation of PBMC and RBC membranes, levels of serum glutamate, serotonin, homocysteine, ROS, lactate and LDH-A expression increased significantly with severity of ID whereas changes in RBC membrane β-actin, serum BDNF, TNF-α and IL-6 was found non-significant. Structural abnormalities of RBC were more in severely disabled children compared to mildly affected ones. The oxidative stress remained a crucial factor with severity of disability. This is confirmed not only by RBC alterations but also with other cellular dysregulations. The present article extends unique insights of how severity of disability is correlated with various clinical, cellular and molecular markers of blood. This unique study primarily focuses on the strong predictors of severity of disability and their associations via brain-blood axis.

The concomitant lower concentrations of vitamins B6, B9 and B12 may cause methylation deficiency in autistic children

Autism spectrum disorder (ASD) is characterized by severe and persistent difficulties in social communication and social interaction at multiple levels. Recently, metabolic disorders have been associated with most cases of patients with ASD. The aim of this study was to investigate, through a new and more sophisticated mass technique, such as UHPLC-mass spectrometry (Q-exactive analyzer), alteration in metabolisms analyzing ASD children urine samples from children showing simultaneous vitamin B6, B9 and B12 deficiencies. This in order to study how these concurrent deficiencies may influence some phenotypic aspects of autistic disorder. Thus, urinary metabolic patterns specific to ASD were explored at an early age in 60 children with ASD, showing lower three vitamins levels, and 60 corresponding controls (age group 3-8, M: F=42:18). The results showed significant block of cystathionine formation with consequent accumulation of homocysteine. A lower glutathione levels (GSH), with reduction of essential intracellular reducing environment required for normal immune function, detoxification capacity and redox-sensitive enzyme activity. Increased concentration of 5-methyltetrahydrofolate, which leads to a lower availability of methyl group and significant decrease in urinary methionine and S-adenosyl-L-methionine (SAM) concentrations, the major methyl donor. The latter justify the well-known reduction in protein and DNA methylation reported in autistic children. As a final consideration, the concomitant deficiencies of all three B vitamins, recorded in a significant number of autistic children, suggests that intestinal dysbiosis in these patients may be the main cause of a reduction in their absorption, in addition to the genetic mutation of a specific gene.

Redox Mechanisms in Neurodegeneration: From Disease Outcomes to Therapeutic Opportunities

SIGNIFICANCE

Once considered to be mere by-products of metabolism, reactive oxygen, nitrogen and sulfur species are now recognized to play important roles in diverse cellular processes such as response to pathogens and regulation of cellular differentiation. It is becoming increasingly evident that redox imbalance can impact several signaling pathways. For instance, disturbances of redox regulation in the brain mediate neurodegeneration and alter normal cytoprotective responses to stress. Very often small disturbances in redox signaling processes, which are reversible, precede damage in neurodegeneration. Recent Advances: The identification of redox-regulated processes, such as regulation of biochemical pathways involved in the maintenance of redox homeostasis in the brain has provided deeper insights into mechanisms of neuroprotection and neurodegeneration. Recent studies have also identified several post-translational modifications involving reactive cysteine residues, such as nitrosylation and sulfhydration, which fine-tune redox regulation. Thus, the study of mechanisms via which cell death occurs in several neurodegenerative disorders, reveal several similarities and dissimilarities. Here, we review redox regulated events that are disrupted in neurodegenerative disorders and whose modulation affords therapeutic opportunities.

CRITICAL ISSUES

Although accumulating evidence suggests that redox imbalance plays a significant role in progression of several neurodegenerative diseases, precise understanding of redox regulated events is lacking. Probes and methodologies that can precisely detect and quantify in vivo levels of reactive oxygen, nitrogen and sulfur species are not available.

FUTURE DIRECTIONS

Due to the importance of redox control in physiologic processes, organisms have evolved multiple pathways to counteract redox imbalance and maintain homeostasis. Cells and tissues address stress by harnessing an array of both endogenous and exogenous redox active substances. Targeting these pathways can help mitigate symptoms associated with neurodegeneration and may provide avenues for novel therapeutics. Antioxid. Redox Signal. 30, 1450-1499.

Autistic traits and components of the folate metabolic system: an explorative analysis in the eastern Indian ASD subjects

Objectives: Proper metabolism of the folate is crucial for maintaining DNA integrity, chromosome structure, methylation, as well as gene expression, and thus, folate is speculated to contribute to the etiology of different disorders. Since the etiology of autism spectrum disorder (ASD) is believed to be influenced by both genetic and environmental factors, we hypothesized that functional single nucleotide polymorphisms (SNPs) affecting folate metabolic pathway may have a causal role in the etiology of ASD. Methods: We analyzed three SNPs, rs2071010, rs2298444 and rs1801198 (in the folate receptor 1, folate receptor 2 and transcobalamin 2, respectively), in 867 ethnically matched subjects including 206 ASD probands and 286 controls. Plasma vitamin B₆ and folate were measured in age-matched probands and controls. Results: ASD probands showed a higher frequency of rs2298444 'A' allele (P = 0.01) and genotypes with 'A' allele (P = 0.03) when compared with the controls. rs1801198 'C' allele and 'CG' genotype also showed higher occurrence in the probands (P = 0.009 and 0.005, respectively). Gender-based stratified analysis revealed a significant higher frequency of rs2298444 'A' allele (P = 0.003), genotypes with rs2298444 'A' allele (P = 0.003) and rs1801198 CG (P = 0.001) in the male probands. Studied variants also showed statistically significant associations with ASD-associated traits measured by the Childhood Autism Rating Scale. ASD subjects exhibited gross deficiency in vitamin B₆ level when compared with age-matched controls (P < 0.001), which correlated with risk genetic variants. Discussion: We infer from this pioneering study on eastern Indian subjects that vitamin B₆ deficiency, along with risk gene variants, may affect ASD-associated symptoms, warranting further investigation in large cohorts.

Comparison of serum B12, folate and homocysteine concentrations in children with autism spectrum disorder or attention deficit hyperactivity disorder and healthy controls

OBJECTIVE

We aimed to investigate the serum concentrations of vitamin B12, folate and homocysteine in children diagnosed with attention deficit hyperactivity disorder (ADHD) or autism spectrum disorder (ASD) and healthy controls.

MATERIALS AND METHODS

Serum vitamin B12, folate and homocysteine concentrations were measured in 118 children (48 children diagnosed with ADHD, 35 children diagnosed with ASD and 35 healthy controls). Symptom severity in the ADHD and ASD groups was evaluated by the Childhood Autism Rating Scale and Turgay-DSM-IV-Based Screening and Assessment Scale for Disruptive Behavior Disorders. Multivariate analysis of covariance was used to evaluate the effects of diagnosis and gender on biochemical parameters.

RESULTS

The ADHD and ASD groups and the healthy controls differed significantly regarding vitamin B12 and homocysteine concentrations, but not folate levels. Patients with ASD had the lowest vitamin B12 and the highest homocysteine levels. Vitamin B12 levels correlated negatively with hyperactivity and/orimpulsivity and oppositionality symptoms in children with ADHD. There were no relationships between psychometric evaluations and laboratory measurements in children with ASD. Gender did not affect vitamin concentrations.

CONCLUSION

Previous studies found that vitamin B12 was reduced while homocysteine was elevated among patients with ADHD and ASDs. Our results also support those reported previously. Oppositionality and hyperactivity and/orimpulsivity may be related to vitamin B12 and homocysteine levels in children with ADHD. Further studies are required to define the role of these parameters and effects on the etiology and clinical manifestations of ASD and ADHD.

PON1 DNA methylation and neurobehavior in Mexican-American children with prenatal organophosphate exposure

PON1 is a multifunctional enzyme involved in oxidative stress and detoxification of some organophosphate (OP) pesticides. It has been associated with nervous system diseases like Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, and autism. We previously found that PON1 susceptible genotypes were associated with lower IQ scores in children. Epigenetic marks, such as DNA methylation, can regulate gene expression. Yet, data on whether DNA methylation may influence the relationship between PON1 levels and neurobehavior are limited. In this study, we used Illumina 450K and EPIC BeadChip arrays to assess PON1 DNA methylation in blood specimens collected from children (n = 238) at birth (cord blood) and age 7 years and examined their relationship with cognitive outcomes. The Wechsler Intelligence Scale for Children was used to assess Full Scale IQ and four composite measures (Verbal Comprehension, Perceptual Reasoning, Working Memory, and Processing Speed Indexes) in 7-year-old children. We observed a consistent yet nonsignificant inverse relationship of methylation at several CpG sites close to the PON1 transcription start site with Full Scale IQ and other composite measures of cognition. We also found an inverse relationship between cord blood methylation at cg15887283 with working memory and a positive association of 7-year-old methylation at cg22798737 with processing speed, independent of OP exposure. However, none of the associations remained significant after accounting for multiple comparisons. This study provides some evidence of the role DNA methylation may play in the known relationship between PON1 and neurobehavior in children, however it appears to be only suggestive and warrants additional research.

The Levels of Vitamin D, Vitamin D Receptor, Homocysteine and Complex B Vitamin in Children with Autism Spectrum Disorders

Objective

Autism spectrum disorder (ASD) is a complex neurodevelopmental syndrome with an increasingly prevalent etiology, yet not fully understood. It has been thought that vitamin D, complex B vitamin levels and homocysteine are associated with environmental factors and are important in ASD. The aim of this study was to examine serum vitamin D, vitamin D receptor (VDR), homocysteine, vitamin B6, vitamin B12 and folate levels in ASD.

Methods

In this study, serum vitamin D and VDR, homocysteine, vitamins B6, B12 and folate levels were determined in 60 patients with ASD (aged 3 to 12 years) and in 45 age-gender matched healthy controls. In addition, calcium, phosphorus and alkaline phosphatase, which are associated with vitamin D metabolism, were measured from serum in both groups. ASD severity was evaluted by the Childhood Autism Rating Scale (CARS).

Results

Serum vitamin D and VDR were substantially reduced in patients with ASD in comparision to control group. However, homocysteine level was significantly higher and vitamin B6, vitamin B12 and folate were also reduced in patients with ASD. Total CARS score showed a positive association with homocysteine and a negative correlation with vitamins D,B6, B12, folate and VDR.

Conclusion

This comprehensive study, which examines many parameters has shown that low serum levels of vitamins D, B6, B12, folate and VDR as well as high homocysteine are important in the etiopathogenesis of ASD. However, further studies are required to define the precise mechanism(s) of these parameters and their contributions to the etiology and treatment of ASD.

Genetics and epigenetics of autism: A Review

Autism is a developmental disorder that starts before age 3 years, and children with autism have impairment in both social interaction and communication, and have restricted, repetitive, and stereotyped patterns of behavior, interests, and activities. There is a strong heritable component of autism and autism spectrum disorder (ASD) as studies have shown that parents who have a child with ASD have a 2-18% chance of having a second child with ASD. The prevalence of autism and ASD have been increasing during the last 3 decades and much research has been carried out to understand the etiology, so as to develop novel preventive and treatment strategies. This review aims at summarizing the latest research studies related to autism and ASD, focusing not only on the genetics but also some epigenetic findings of autism/ASD. Some promising areas of research using transgenic/knockout animals and some ideas related to potential novel treatment and prevention strategies will be discussed.

Periconceptional folate deficiency leads to autism-like traits in Wistar rat offspring

BACKGROUND

Folates in their role as key one carbon donors, are essential for two major pathways: the synthesis of DNA and RNA precursors and DNA methylation. A growing body of evidence from epidemiological studies indicates a possible association between nutritional and functional deficiency in folates and Autism Spectrum Disorders (ASD). However, there are no available behavioral animal studies on periconceptional one‑carbon donor deficiency during gestation and the autistic phenotype.

OBJECTIVE

The objective of this study was to determine if the periconceptional alteration of one‑carbon metabolism induced with a folate deficient diet would affect the behaviour of rat offspring.

METHODS

Female Wistar rats were divided in two groups: control (basal diet, in compliance with standards of regular laboratory diets), or exposed during one month before breeding until Gestational Day 15 to a modified diet with no added folic acid (0.2mg/kg of food), reduced choline (750mg/kg of food), and added 1% SST (a non-absorbable antibiotic used to inhibit folate synthesis by gut bacteria). We administered behavioral tests to offspring, i.e., open field (P20), social interactions (P25), marble burying (P30), elevated plus maze (P35), and prepulse inhibition of the acoustic startle reflex (sensorimotor gating) (P45). Blood homocysteine levels were used to confirm the deficit in one‑carbon donors.

RESULTS

Compared to controls, offspring with the periconceptional deficit in folate showed: (i) congenital body malformations; (ii) reduced social interactions, with a ~30% decrease in social sniffing behavior; (iii) reduced exploration of the open arm by 50% in the elevated plus maze test, indicating increased anxiety; (iv) a ~160% increased number of marbles buried, indicating repetitive behaviors; and (v) altered sensorimotor gating, with a global 50% decrease in startle inhibition.

CONCLUSION

Maternal periconceptional deficit in folate provokes alterations in the behavior of offspring relevant to the autistic-like phenotype.

Individuals with autism have higher 8-Iso-PGF2α levels than controls, but no correlation with quantitative assay of Paraoxonase 1 serum levels

Autism spectrum disorder (ASD) represents a very large set of neurodevelopmental issues with diverse clinical outcomes. Various hypotheses have been put forth for the etiology of autism spectrum disorder, including issues pertaining to oxidative stress. In this study, we conducted measurements of serum 8-Iso-Prostaglanding F2 α (8-iso-PGF2α, which is the results of non-enzimatically mediated polyunsaturated fatty acid oxidation) in a population of individuals with autism and a control group of age and sex matched controls. A quantitative assay of Paraoxonase 1 (PON1) was conducted. Data regarding comorbidities, structural MRI scans, medication, intelligence quotient (IQ) and Childhood Autism Rating Scale scores (CARS) were also included in our study. Our results show that patients diagnosed with autism have higher levels of 8-iso-PGF2α than their neurotypical counterparts. Levels of this particular metabolite, however, do not correlate with quantitative serum levels of Paraoxonase 1, which has been shown to be altered in individuals with autism. Neither 8-iso-PGF2α nor quantitative levels of PON1 provide any meaningful correlation with clinical or neuroimaging data in this study group. Future research should focus on providing data regarding PON 1 phenotype, in addition to standard quantitative measurements, in relation to 8-iso-PGF2α as well as other clinical and structural brain findings.

Lactonase Activity and Lipoprotein-Phospholipase A2 as Possible Novel Serum Biomarkers for the Differential Diagnosis of Autism Spectrum Disorders and Rett Syndrome: Results from a Pilot Study

Rett syndrome (RTT) and autism spectrum disorders (ASDs) are not merely expression of brain dysfunction but also reflect the perturbation of physiological/metabolic homeostasis. Accordingly, both disorders appear to be associated with increased vulnerability to toxicants produced by redox imbalance, inflammation, and pollution, and impairment of systemic-detoxifying agents could play a role in the exacerbation of these detrimental processes. To check this hypothesis, the activities of two mechanistically related blood-based enzymes, paraoxonase-1 (arylesterase, paraoxonase, and lactonase), and lipoprotein-associated phospholipase A₂ (Lp-PLA₂) were measured in the serum of 79 ASD and 95 RTT patients, and 77 controls. Lactonase and Lp-PLA₂ showed a similar trend characterized by significantly lower levels of both activities in ASD compared to controls and RTT (p < 0.001 for all pairwise comparisons). Noteworthy, receiving operator curve (ROC) analysis revealed that lactonase and, mostly, Lp-PLA₂ were able to discriminate between ASD and controls (lactonase: area under curve, AUC = 0.660; Lp-PLA₂, AUC = 0.780), and, considering only females, between ASD and RTT (lactonase, AUC = 0.714; Lp-PLA₂, AUC = 0.881). These results suggest that lactonase and, especially, Lp-PLA₂ activities might represent novel candidate biomarkers for ASD.

New Perspective on Impact of Folic Acid Supplementation during Pregnancy on Neurodevelopment/Autism in the Offspring Children - A Systematic Review

It has been conclusively established that folic acid supplementation prior to and during early pregnancy (up to 12 weeks of gestation) can prevent neural tube defects (NTDs). We hypothesized that folate effects may extend from neuro-structural defects to alterations in neuro-behavioural and emotional skills including autism spectrum disorders (ASDs) and other developmental disorders. The objective of this review was to comprehensively evaluate evidence on the impact of folic acid on neurodevelopment other than NTDs. We conducted an online search of relevant literature compiled by the National Library of Medicine from Medline and EMBASE (searched on Dec 31, 2014: http://www.ncbi.nlm.nih.gov/entrez/query/fcgi and http://www.elsevier.com/online-tools/embase). We first created 3 files (search restricted to English literature) using the following key words: 1) folate or folic acid (171322 papers identified by this search); 2) maternal or pregnancy or pregnant or gestation or gestational or prenatal or antenatal or periconception or periconceptional (1349219 papers identified by this search); and 3) autism or autism spectrum disorders or developmental delay or development or neurodevelopment or mental or cognitive or language or personal-social or gross motor or fine motor or behaviour or intellectual or intelligence or Bayley Scale (8268145 papers identified by this search). We then merged the 3 files and reviewed the papers that addressed these three issues simultaneously. A total of 22 original papers that examined the association between folic acid supplementation in human pregnancy and neurodevelopment/autism were identified after the screening, with 15 studies showing a beneficial effect of folic acid supplementation on neurodevelopment/autism, 6 studies showed no statistically significant difference, while one study showed a harmful effect in > 5 mg folic acid supplementation/day during pregnancy. Folic acid supplementation in pregnancy may have beneficial effects on the neurodevelopment of children beyond its proven effect on NTDs.

Body fluid levels of neuroactive amino acids in autism spectrum disorders: a review of the literature

A review of studies on the body fluid levels of neuroactive amino acids, including glutamate, glutamine, taurine, gamma-aminobutyric acid (GABA), glycine, tryptophan, d-serine, and others, in autism spectrum disorders (ASD) is given. The results reported in the literature are generally inconclusive and contradictory, but there has been considerable variation among the previous studies in terms of factors such as age, gender, number of subjects, intelligence quotient, and psychoactive medication being taken. Future studies should include simultaneous analyses of a large number of amino acids [including d-serine and branched-chain amino acids (BCAAs)] and standardization of the factors mentioned above. It may also be appropriate to use saliva sampling to detect amino acids in ASD patients in the future—this is noninvasive testing that can be done easily more frequently than other sampling, thus providing more dynamic monitoring.

A Study of Single Nucleotide Polymorphisms of the SLC19A1/RFC1 Gene in Subjects with Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a group of neurodevelopmental disorders with complex genetic etiology. Recent studies have indicated that children with ASD may have altered folate or methionine metabolism, suggesting that the folate–methionine cycle may play a key role in the etiology of ASD. SLC19A1, also referred to as reduced folate carrier 1 (RFC1), is a member of the solute carrier group of transporters and is one of the key enzymes in the folate metabolism pathway. Findings from multiple genomic screens suggest the presence of an autism susceptibility locus on chromosome 21q22.3, which includes SLC19A1. Therefore, we performed a case-control study in a Japanese population. In this study, DNA samples obtained from 147 ASD patients at the Kanazawa University Hospital in Japan and 150 unrelated healthy Japanese volunteers were examined by the sequence-specific primer-polymerase chain reaction method pooled with fluorescence correlation spectroscopy. p < 0.05 was considered to represent a statistically significant outcome. Of 13 single nucleotide polymorphisms (SNPs) examined, a significant p-value was obtained for AA genotype of one SNP (rs1023159, OR = 0.39, 95% CI = 0.16–0.91, p = 0.0394; Fisher’s exact test). Despite some conflicting results, our findings supported a role for the polymorphism rs1023159 of the SLC19A1 gene, alone or in combination, as a risk factor for ASD. However, the findings were not consistent after multiple testing corrections. In conclusion, although our results supported a role of the SLC19A1 gene in the etiology of ASD, it was not a significant risk factor for the ASD samples analyzed in this study.

Plasma phthalate and bisphenol a levels and oxidant-antioxidant status in autistic children

Phthalates and bisphenol A (BPA) are endocrine disruting chemicals (EDCs) that are suggested to exert neurotoxic effects. This study aimed to determine plasma phthalates and BPA levels along with oxidant/antioxidant status in autistic children [n=51; including 12 children were diagnosed with "Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS)]. Plasma levels of BPA, di (2-ethylhexyl)-phthalate (DEHP) and its main metabolite mono (2-ethylhexyl)-phthalate (MEHP); thiobarbituric acid reactive substance (TBARS) and carbonyl groups; erythrocyte glutathione peroxidase (GPx1), thioredoxin reductase (TrxR), catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR) activities and glutathione (GSH) and selenium levels were measured. Plasma BPA levels of children with PDD-NOS were significantly higher than both classic autistic children and controls (n=50). Carbonyl, selenium concentrations and GPx1, SOD and GR activities were higher (p<0.05); CAT activity was markedly lower in study group. BPA exposure might be associated with PDD-NOS. Intracellular imbalance between oxidant and antioxidant status might facilitate its neurotoxicity.

Increased homocysteine levels correlate with the communication deficit in children with autism spectrum disorder

The clinical significance of high levels of homocysteine in autism spectrum disorder (ASD) is unknown. An experimental study was conducted in order to evaluate the concentration of homocysteine in children with ASD and typically developing children and to analyse any relationships with the severity of core symptoms of ASD and other clinical features (drugs, co-morbidities, gender, age, diet). Core symptoms of autism were evaluated by DSM-IV criteria. Homocysteine, glutathione, methionine, 3-nitrotyrosine were measured in urine. The increase in homocysteine concentration was significantly and directly correlated with the severity of the deficit in communication skills, but was unrelated to deficit in socialisation or repetitive/restricted behaviour. Urinary homocysteine concentration may be a possible biomarker for communication deficits in ASD and a potential diagnostic tool useful to evaluate new treatment options since no treatment for core symptoms of ASD are available.

Active ribosomal genes, translational homeostasis and oxidative stress in the pathogenesis of schizophrenia and autism

BACKGROUND

Infantile autism and schizophrenia are severe multifactorial disorders with a pronounced genetic predisposition. Their pathogeneses are often associated with oxidative stress in the brain. Previously, we established that a cell's resistance to oxidative stress depended on the copy number of transcriptionally active genes for rRNA (ribosomal genes) in the cell's genome. The feature is measured cytogenetically in cultured lymphocytes derived from patients. It varies from 120 up to 190 copies per diploid genome, with an arithmetic mean of 150±4 (SE) copies in a healthy population (n=239), being considerably lower, according to our previous results, in a sample of patients with rheumatoid arthritis (n=49), another multifactorial disease with a proven significant role of oxidative stress in its pathogenesis: from 115 to 165 copies, with a mean of 140±4 (SE). Conversely, a sample of schizophrenic patients (n=42) previously showed a higher value of copy number of active rRNA genes compared with a healthy population: from 145 to 190 copies, with a mean of 170±4. This fact is of special interest in the context of the well-known, but still unexplained phenomenon of the reduced comorbidity rate of schizophrenia and rheumatoid arthritis.

RESULTS

The copy number of active ribosomal genes was estimated in a sample of autistic children (n=51). In contrast with the schizophrenic patients studied previously, we found that the values were significantly lower than those in the healthy population: from 125 to 160 copies, with a mean of 142±5. In this work, we suggest a mathematical model of the oxidative stress dynamics on the basis of Lotka-Volterra's approach to predator-prey interactions. In our model, the 'prey' represents reactive oxygen species, whereas the 'predator' simulates molecules of the antioxidant enzymes. The rate of biosynthesis of the latter is limited by the number of ribosomes available, which, in turn, is determined by the copy number of active rRNA genes. Analysis of the model showed the existence of a unique equilibrium point that makes biological sense. The reactive oxygen species level oscillatory approaches this equilibrium value, which inversely depends on the copy number of active rRNA genes.

DISCUSSION

Our findings confirm the hypothesis of disturbance of the 'translational homeostasis' in the pathogeneses of autism and schizophrenia, and would help explain why oxidative stress markers are discovered in most autism studies, whereas similar reports related to schizophrenia are far less consistent.

Nutritional status of individuals with autism spectrum disorders: do we know enough?

The incidence of individuals with autism spectrum disorders (ASDs) is on the rise; therefore, well-timed screening is important. Given that this is a nutritionally vulnerable population, it is imperative to conduct a detailed nutritional assessment so that timely and intensive interventions can be recommended. This review article summarizes the research, focusing on the nutritional status of individuals with ASDs based on their anthropometric measurements, biomarkers, and dietary assessments. Research examining anthropometric measurements reveals an abnormally accelerated rate of growth among children with autism but shows inconsistent findings on the prevalence of overweight/obesity in comparison with typically growing children. Although dysregulated amino acid metabolism, increased homocysteine, and decreased folate, vitamins B-6 and B-12, and vitamin D concentrations have been proposed as possible biomarkers for an early diagnosis of ASDs, research investigating their association with age, gender, severity, and other comorbid psychiatric/nonpsychiatric disorders is lacking. There is consensus that children with autism have selective eating patterns, food neophobia, limited food repertoire, and sensory issues. Although inadequate micronutrient but adequate macronutrient intakes are increasingly reported, there are inconsistent results about the extent and type of nutrient deficiencies. Identification and development of nutritional assessment indicators that serve as early warning signs during routine practice beginning at birth and extending throughout the child's growth are necessary. With this population aging, there is also a dire need to study the adult population. A more vigorous role by nutrition professionals is warranted because management of potential comorbidities and contributory factors may be particularly problematic.

Multifactorial Origin of Neurodevelopmental Disorders: Approaches to Understanding Complex Etiologies

A significant body of evidence supports the multifactorial etiology of neurodevelopmental disorders (NDDs) affecting children. The present review focuses on early exposure to environmental chemicals as a risk factor for neurodevelopment, and presents the major lines of evidence derived from epidemiological studies, underlying key uncertainties and research needs in this field. We introduce the exposome concept that, encompassing the totality of human environmental exposures to multiple risk factors, aims at explaining individual vulnerability and resilience to early chemical exposure. In this framework, we synthetically review the role of variable gene backgrounds, the involvement of epigenetic mechanisms as well as the function played by potential effect modifiers such as socioeconomic status. We describe laboratory rodent studies where the neurodevelopmental effects of environmental chemicals are assessed in the presence of either a “vulnerable” gene background or adverse pregnancy conditions (i.e., maternal stress). Finally, we discuss the need for more descriptive and “lifelike” experimental models of NDDs, to identify candidate biomarkers and pinpoint susceptible groups or life stages to be translated to large prospective studies within the exposome framework.

Bisphenol A induces oxidative stress and mitochondrial dysfunction in lymphoblasts from children with autism and unaffected siblings

Autism is a behaviorally defined neurodevelopmental disorder. Although there is no single identifiable cause for autism, roles for genetic and environmental factors have been implicated in autism. Extensive evidence suggests increased oxidative stress and mitochondrial dysfunction in autism. In this study, we examined whether bisphenol A (BPA) is an environmental risk factor for autism by studying its effects on oxidative stress and mitochondrial function in the lymphoblasts. When lymphoblastoid cells from autistic subjects and age-matched unaffected sibling controls were exposed to BPA, there was an increase in the generation of reactive oxygen species (ROS) and a decrease in mitochondrial membrane potential in both groups. A further subdivision of the control group into two subgroups-unaffected nontwin siblings and twin siblings-showed significantly higher ROS levels without any exposure to BPA in the unaffected twin siblings compared to the unaffected nontwin siblings. ROS levels were also significantly higher in the autism vs the unaffected nontwin siblings group. The effect of BPA on three important mtDNA genes-NADH dehydrogenase 1, NADH dehydrogenase 4, and cytochrome b-was analyzed to observe any changes in the mitochondria after BPA exposure. BPA induced a significant increase in the mtDNA copy number in the lymphoblasts from the unaffected siblings group and in the unaffected twin siblings group vs the unaffected nontwin siblings. In all three genes, the mtDNA increase was seen in 70% of the subjects. These results suggest that BPA exposure results in increased oxidative stress and mitochondrial dysfunction in the autistic subjects as well as the age-matched sibling control subjects, particularly unaffected twin siblings. Therefore, BPA may act as an environmental risk factor for autism in genetically susceptible children by inducing oxidative stress and mitochondrial dysfunction.