Redox metabolism abnormalities in autistic children associated with mitochondrial disease

Advanced glycation endproducts, dityrosine and arginine transporter dysfunction in autism - a source of biomarkers for clinical diagnosis

Background

Clinical chemistry tests for autism spectrum disorder (ASD) are currently unavailable. The aim of this study was to explore the diagnostic utility of proteotoxic biomarkers in plasma and urine, plasma protein glycation, oxidation, and nitration adducts, and related glycated, oxidized, and nitrated amino acids (free adducts), for the clinical diagnosis of ASD.

Methods

Thirty-eight children with ASD (29 male, 9 female; age 7.6 ± 2.0 years) and 31 age-matched healthy controls (23 males, 8 females; 8.6 ± 2.0 years) were recruited for this study. Plasma protein glycation, oxidation, and nitration adducts and amino acid metabolome in plasma and urine were determined by stable isotopic dilution analysis liquid chromatography-tandem mass spectrometry. Machine learning methods were then employed to explore and optimize combinations of analyte data for ASD diagnosis.

Results

We found that children with ASD had increased advanced glycation endproducts (AGEs), N_ε-carboxymethyl-lysine (CML) and N_ω-carboxymethylarginine (CMA), and increased oxidation damage marker, dityrosine (DT), in plasma protein, with respect to healthy controls. We also found that children with ASD had increased CMA free adduct in plasma ultrafiltrate and increased urinary excretion of oxidation free adducts, alpha-aminoadipic semialdehyde and glutamic semialdehyde. From study of renal handling of amino acids, we found that children with ASD had decreased renal clearance of arginine and CMA with respect to healthy controls. Algorithms to discriminate between ASD and healthy controls gave strong diagnostic performance with features: plasma protein AGEs—CML, CMA—and 3-deoxyglucosone-derived hydroimidazolone, and oxidative damage marker, DT. The sensitivity, specificity, and receiver operating characteristic area-under-the-curve were 92%, 84%, and 0.94, respectively.

Conclusions

Changes in plasma AGEs were likely indicative of dysfunctional metabolism of dicarbonyl metabolite precursors of AGEs, glyoxal and 3-deoxyglucosone. DT is formed enzymatically by dual oxidase (DUOX); selective increase of DT as an oxidative damage marker implicates increased DUOX activity in ASD possibly linked to impaired gut mucosal immunity. Decreased renal clearance of arginine and CMA in ASD is indicative of increased arginine transporter activity which may be a surrogate marker of disturbance of neuronal availability of amino acids. Data driven combination of these biomarkers perturbed by proteotoxic stress, plasma protein AGEs and DT, gave diagnostic algorithms of high sensitivity and specificity for ASD.

Electronic supplementary material

The online version of this article (10.1186/s13229-017-0183-3) contains supplementary material, which is available to authorized users.

Comparison of Treatment for Metabolic Disorders Associated with Autism:Reanalysis of Three Clinical Trials

Autism spectrum disorder (ASD) affects about 1 in 45 individuals in the United States, yet effective treatments are yet to be defined. There is growing evidence that ASD is associated with abnormalities in several metabolic pathways, including the inter-connected folate, methylation and glutathione pathways. Several treatments that can therapeutically target these pathways have been tested in preliminary clinical trials. The combination of methylcobalamin (mB12) with low-dose folinic acid (LDFA) and sapropterin, a synthetic form of tetrahydrobiopterin (BH4) have been studied in open-label trials while high-dose folinic acid has been studied in a double-blind placebo controlled trial. All of these treatments have the potential to positively affect folate, methylation and glutathione pathways. Although the effect of mB12/LDFA and BH4 on methylation and glutathione metabolism have been examined in the open-label studies, these changes have not been compared to controls who received a placebo in order to account for the natural variation in the changes in these pathways. Furthermore, the recent study using high-dose folinic acid (HDFA) did not analyze the change in metabolism resulting from the treatment. Thus, we compared changes in methylation and glutathione metabolism and biomarkers of chronic oxidative stress as a result of these three treatments to individuals receiving placebo. In general, mB12/LDFA treatment had a significant effect on glutathione and cysteine metabolism with a medium effect size while BH4 had a significant effect on methylation and markers of chronic oxidative stress with a large effect size. HDFA treatment did not significantly influence biomarkers of methylation, glutathione or chronic oxidative stress. One caveat was that participants in the mB12/LDFA and BH4 studies had significantly worse markers of glutathione metabolism and chronic oxidative stress at baseline, respectively. Thus, the participants selected in these two clinical trials may have been those with the most severe metabolic abnormalities and most expected to respond to these treatments. Overall this study supports the notion that metabolic abnormalities in individuals with ASD may be amenable to targeted treatments and provide some insight into the mechanism of action of these treatments.

Novel biomarkers of metabolic dysfunction is autism spectrum disorder: potential for biological diagnostic markers

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that is behaviorally defined by social and communication impairments and restricted interests and repetitive behaviors. There is currently no biomarkers that can help in the diagnosis. Several studies suggest that mitochondrial dysfunction is commonly involved in ASD pathophysiology, but standard mitochondrial biomarkers are thought to be very variable. In the present study we examine a wide variety of plasma biomarkers of mitochondrial metabolism and the related abnormalities of oxidative stress and apoptosis in 41 ASD patients assessed for ASD severity using the Childhood Autism Rating Scales and 41 non-related age and sex matched healthy controls. Our findings confirm previous studies indicating abnormal mitochondrial and related biomarkers in children with ASD including pyruvate, creatine kinase, Complex 1, Glutathione S-Transferase, glutathione and Caspase 7. As a novel finding, we report that lactate dehydrogenase is abnormal in children with ASD. We also identified that only the most severe children demonstrated abnormalities in Complex 1 activity and Glutathione S-Transferase. Additionally, we find that several biomarkers could be candidates for differentiating children with ASD and typically developing children, including Caspase 7, gluthatione and Glutathione S-Transferase by themselves and lactate dehydrogenase and Complex I when added to other biomarkers in combination. Caspase 7 was the most discriminating biomarker between ASD patients and healthy controls suggesting its potential use as diagnostic marker for the early recognition of ASD pathophysiology. This study confirms that several mitochondrial biomarkers are abnormal in children with ASD and suggest that certain mitochondrial biomarkers can differentiate between ASD and typically developing children, making them possibly useful as a tool to diagnosis ASD and identify ASD subgroups.

Depletion of Stercobilin in Fecal Matter from a Mouse Model of Autism Spectrum Disorders

INTRODUCTION

Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders lacking a clinical biomarker for diagnosis. Emerging evidence shows that intestinal microflora from ASD subjects can be distinguished from controls, suggesting metabolite differences due to the action of intestinal microbes may provide a means for identifying potential biomarkers for ASD.

OBJECTIVES

The aim of this study was to determine if quantitative differences in levels of stercobilin and stercobilinogen, metabolites produced by biological action of intestinal microflora, exist in the fecal matter between an ASD mouse model population and controls.

METHODS

Pairs of fecal samples were collected from two mouse groups, an ASD model group with Timothy syndrome 2 (TS2-NEO) and a gender-matched control group. After centrifugation, supernatant was spiked with an ¹⁸O-labeled stercobilin isotopomer and subjected to solid phase extraction for processing. Extracted samples were spotted on a stainless steel plate and subjected to matrix-assisted laser desorption and ionization mass spectrometry using dihydroxybenzoic acid as the matrix (n = 5). Peak areas for bilins and ¹⁸O-stercobilin isotopomers were determined in each fecal sample.

RESULTS

A 40-45% depletion in stercobilin in TS2-NEO fecal samples compared with controls was observed with p < 0.05; a less dramatic depletion was observed for stercobilinogen.

CONCLUSIONS

The results show that stercobilin depletion in feces is observed for an ASD mouse model vs. controls. This may help to explain recent observations of a less diverse microbiome in humans with ASD and may prove helpful in developing a clinical ASD biomarker.

Mitochondrial dysfunction in the gastrointestinal mucosa of children with autism: A blinded case-control study

Gastrointestinal (GI) symptoms are prevalent in autism spectrum disorder (ASD) but the pathophysiology is poorly understood. Imbalances in the enteric microbiome have been associated with ASD and can cause GI dysfunction potentially through disruption of mitochondrial function as microbiome metabolites modulate mitochondrial function and mitochondrial dysfunction is highly associated with GI symptoms. In this study, we compared mitochondrial function in rectal and cecum biopsies under the assumption that certain microbiome metabolites, such as butyrate and propionic acid, are more abundant in the cecum as compared to the rectum. Rectal and cecum mucosal biopsies were collected during elective diagnostic colonoscopy. Using a single-blind case-control design, complex I and IV and citrate synthase activities and complex I-V protein quantity from 10 children with ASD, 10 children with Crohn’s disease and 10 neurotypical children with nonspecific GI complaints were measured. The protein for all complexes, except complex II, in the cecum as compared to the rectum was significantly higher in ASD samples as compared to other groups. For both rectal and cecum biopsies, ASD samples demonstrated higher complex I activity, but not complex IV or citrate synthase activity, compared to other groups. Mitochondrial function in the gut mucosa from children with ASD was found to be significantly different than other groups who manifested similar GI symptomatology suggesting a unique pathophysiology for GI symptoms in children with ASD. Abnormalities localized to the cecum suggest a role for imbalances in the microbiome, potentially in the production of butyrate, in children with ASD.

Autism, Mitochondria and Polybrominated Diphenyl Ether Exposure

BACKGROUND

Autism spectrum disorders (ASD) are a growing concern with more than 1 in every 68 children affected in the United States by age 8. Limited scientific advances have been made regarding the etiology of autism, with general agreement that both genetic and environmental factors contribute to this disorder.

OBJECTIVE

To explore the link between exposure to PBDE, mitochondrial dysfunction and autism risk.

RESULTS

Perinatal exposures to PBDEs may contribute to the etiology or morbidity of ASD including mitochondrial dysfunction based on (i) their increased environmental abundance and human exposures, (ii) their activity towards implicated in neuronal development and synaptic plasticity including mitochondria, and (iii) their bioaccumulation in mitochondria.

CONCLUSION

In this review, we propose that PBDE, and possibly other environmental exposures, during child development can induce or compound mitochondrial dysfunction, which in conjunction with a dysregulated antioxidant response, increase a child's susceptibility of autism.

Predictive value of selected biomarkers related to metabolism and oxidative stress in children with autism spectrum disorder

Autism spectrum disorder (ASD) as a neurodevelopmental disorder is characterized by impairments in social interaction, communication, and restricted, repetitive behavior. Several and reproducible studies have suggested that oxidative stress may represent one of the primary etiological mechanism of ASD that can be targeted for therapeutic intervention. In the present study, multiple regression and combined receiver operating characteristic (ROC) analysis were used to search for a relationship between impaired energy and oxidative metabolic pathways in the etiology of ASD and to find the linear combination that maximizes the partial area under a ROC curve for a pre-identified set of markers related to energy metabolism and oxidative stress. Thirty children with ASD and 30 age and gender matched controls were enrolled in the study. Using either spectrophotometric or ELISA-colorimetric assay, levels of lipid peroxides, vitamin E, vitamin C, glutathione (GSH)/glutathione disulfide (GSSG) together with the enzymatic activity of catalase, plasma glutathione peroxidase (GPx), and blood superoxide dismutase (SOD), were measured in peripheral blood samples, as biomarkers related to oxidative stress. Creatine kinase, ectonucleotidases (ADPase and ATPase) Na⁺/K⁺ (ATPase), lactate, inorganic phosphate, and levels of adenosine monophosphate (AMP), adenosine diphosphate (ADP), and adenosine triphosphate (ATP) together with adenylate energy charge, were also measured as markers of impaired energy metabolism. Statistical analysis using ROC curves, multiple and logistic regression were performed. A remarkable increase in the area under the curve for most of the combined markers, representing both energy impaired metabolism or oxidative stress, was observed by using combined ROC analyses. Moreover, higher specificity and sensitivity of the combined markers were also reported. The present study indicated that the measurement of the predictive value of selected biomarkers related to energy metabolism and oxidative stress in children with ASD using ROC analysis should lead to the better identification of the etiological mechanism of ASD associated with metabolism and diet. Agents with activity against the impaired metabolic pathway associated with ASD including the metabolic defects and involved enzymes hold a promise as a novel therapy for ASD.

Glutathione as a Redox Biomarker in Mitochondrial Disease-Implications for Therapy

Technical advances in the ability to measure mitochondrial dysfunction are providing new insights into mitochondrial disease pathogenesis, along with new tools to objectively evaluate the clinical status of mitochondrial disease patients. Glutathione (l-ϒ-glutamyl-l-cysteinylglycine) is the most abundant intracellular thiol, and the intracellular redox state, as reflected by levels of oxidized (GSSG) and reduced (GSH) glutathione, as well as the GSH/GSSG ratio, is considered to be an important indication of cellular health. The ability to quantify mitochondrial dysfunction in an affected patient will not only help with routine care, but also improve rational clinical trial design aimed at developing new therapies. Indeed, because multiple disorders have been associated with either primary or secondary deficiency of the mitochondrial electron transport chain and redox imbalance, developing mitochondrial therapies that have the potential to improve the intracellular glutathione status has been a focus of several clinical trials over the past few years. This review will also discuss potential therapies to increase intracellular glutathione with a focus on EPI-743 (α-tocotrienol quinone), a compound that appears to have the ability to modulate the activity of oxidoreductases, in particular NAD(P)H:quinone oxidoreductase 1.

The joint effect of air pollution exposure and copy number variation on risk for autism

Autism spectrum disorder is a complex trait with a high degree of heritability as well as documented susceptibility from environmental factors. In this study the contributions of copy number variation, exposure to air pollutants, and the interaction between the two on autism risk, were evaluated in the population-based case-control Childhood Autism Risks from Genetics and Environment (CHARGE) Study. For the current investigation, we included only those CHARGE children (a) who met criteria for autism or typical development and (b) for whom our team had conducted both genetic evaluation of copy number burden and determination of environmental air pollution exposures based on mapping addresses from the pregnancy and early childhood. This sample consisted of 158 cases of children with autism and 147 controls with typical development. Multiple logistic regression models were fit with and without environmental variable-copy number burden interactions. We found no correlation between average air pollution exposure from conception to age 2 years and the child's CNV burden. We found a significant interaction in which a 1SD increase in duplication burden combined with a 1SD increase in ozone exposure was associated with an elevated autism risk (OR 3.4, P < 0.005) much greater than the increased risks associated with either genomic duplication (OR 1.85, 95% CI 1.25-2.73) or ozone (OR 1.20, 95% CI 0.93-1.54) alone. Similar results were obtained when CNV and ozone were dichotomized to compare those in the top quartile relative to those having a smaller CNV burden and lower exposure to ozone, and when exposures were assessed separately for pregnancy, the first year of life, and the second year of life. No interactions were observed for other air pollutants, even those that demonstrated main effects; ozone tends to be negatively correlated with the other pollutants examined. While earlier work has demonstrated interactions between the presence of a pathogenic CNV and an environmental exposure [Webb et al., 2016], these findings appear to be the first indication that global copy number variation may increase susceptibility to certain environmental factors, and underscore the need to consider both genomics and environmental exposures as well as the mechanisms by which each may amplify the risks for autism associated with the other. Autism Res 2017, 10: 1470-1480. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

Expression of Reactive Oxygen Species-Related Transcripts in Egyptian Children With Autism

The molecular basis of the pathophysiological role of oxidative stress in autism is understudied. Herein, we used polymerase chain reaction (PCR) array to analyze transcriptional pattern of 84 oxidative stress genes in peripheral blood mononuclear cell pools isolated from 32 autistic patients (16 mild/moderate and 16 severe) and 16 healthy subjects (each sample is a pool from 4 autistic patients or 4 controls). The PCR array data were further validated by quantitative real-time PCR in 80 autistic children (55 mild/moderate and 25 severe) and 60 healthy subjects. Our data revealed downregulation in GCLM, SOD2, NCF2, PRNP, and PTGS2 transcripts (1.5, 3.8, 1.2, 1.7, and 2.2, respectively;P < .05 for all) in autistic group compared with controls. In addition, TXN and FTH1 exhibited 1.4- and 1.7-fold downregulation, respectively, in severe autistic patients when compared with mild/moderate group (P = .005 and .0008, respectively). This study helps in a better understanding of the underlying biology and related genetic factors of autism, and most importantly, it presents suggested candidate biomarkers for diagnosis and prognosis purposes as well as targets for therapeutic intervention.

The Effect of Mitochondrial Supplements on Mitochondrial Activity in Children with Autism Spectrum Disorder

Treatment for mitochondrial dysfunction is typically guided by expert opinion with a paucity of empirical evidence of the effect of treatment on mitochondrial activity. We examined citrate synthase and Complex I and IV activities using a validated buccal swab method in 127 children with autism spectrum disorder with and without mitochondrial disease, a portion of which were on common mitochondrial supplements. Mixed-model linear regression determined whether specific supplements altered the absolute mitochondrial activity as well as the relationship between the activities of mitochondrial components. Complex I activity was increased by fatty acid and folate supplementation, but folate only effected those with mitochondrial disease. Citrate synthase activity was increased by antioxidant supplementation but only for the mitochondrial disease subgroup. The relationship between Complex I and IV was modulated by folate while the relationship between Complex I and Citrate Synthase was modulated by both folate and B12. This study provides empirical support for common mitochondrial treatments and demonstrates that the relationship between activities of mitochondrial components might be a marker to follow in addition to absolute activities. Measurements of mitochondrial activity that can be practically repeated over time may be very useful to monitor the biochemical effects of treatments.

Evolution in the Understanding of Autism Spectrum Disorder: Historical Perspective

The study of the evolution in the diagnosis and treatment of autism is a lesson in the dangers of medical beliefs or doctrines that are not grounded in medical science. The early descriptions of autism suggested that it was the result of childhood psychoses or psychodynamic disturbances of parent-child relationships. This flawed conceptualization of autism spectrum disorders (ASD) gave way to advances in medical science, which have established ASD as a neurobiological disorder of early brain development. There are many genetic, epigenetic, metabolic, hormonal, immunological, neuroanatomical and neurophysiological etiologies of ASD, as well as an array of gastrointestinal and other systemic co-morbid disorders. Thus, ASD are a biologically heterogeneous population with extensive neurodiversity. Early identification and understanding of ASD is crucial; interventions at younger ages are associated with improved outcomes. The advent of understanding the biological sub-phenotypes of ASD, along with targeted medical therapies, coupled with a multimodal therapeutic approach that encompasses behavioral, educational, social, speech, occupational, creative arts, and other forms of therapies has created a new and exciting era for individuals with ASD and their families: "personalized" and "precision" medical care based upon underlying biological sub-phenotypes and clinical profiles. For many individuals and their families dealing with the scourge of autism, their long and frustrating diagnostic journey is beginning to come to an end, with a hope for improved outcomes and quality of life.

Quantitation of plasma thiamine, related metabolites and plasma protein oxidative damage markers in children with autism spectrum disorder and healthy controls

AIMS/HYPOTHESIS

To assess thiamine and related metabolite status by analysis of plasma and urine in autistic children and healthy controls, correlations to clinical characteristics and link to plasma protein markers of oxidative damage.

METHODS

27 children with autism (21 males and 6 females) and 21 (15 males and 6 females) age-matched healthy control children were recruited. The concentration of thiamine and related phosphorylated metabolites in plasma and urine and plasma protein content of dityrosine, N-formylkynurenine and 3-nitrotyrosine was determined.

RESULTS

Plasma thiamine and thiamine monophosphate concentrations were similar in both study groups (median [lower-upper quartile]): autistic children - 6.60 nM (4.48-8.91) and 7.00 nM (5.51-8.55), and healthy controls - 6.82 nM (4.47-7.02) and 6.82 nM (5.84-8.91), respectively. Thiamine pyrophosphate (TPP) was decreased 24% in autistic children compared to healthy controls: 6.82 nM (5.81-8.52) versus 9.00 nM (8.41-10.71), p < .01. Urinary excretion of thiamine and fractional renal clearance of thiamine did not change between the groups. No correlation was observed between clinical markers and the plasma and urine thiamine concentration. Plasma protein dityrosine content was increased 88% in ASD. Other oxidative markers were unchanged.

CONCLUSIONS/INTERPRETATION

Autistic children had normal plasma and urinary thiamine levels whereas plasma TPP concentration was decreased. The latter may be linked to abnormal tissue handling and/or absorption from gut microbiota of TPP which warrants further investigation. Increased plasma protein dityrosine may reflect increased dual oxidase activity in response to change in mucosal immunity and host-microbe homeostasis.

The relationship between mercury and autism: A comprehensive review and discussion

The brain pathology in autism spectrum disorders (ASD) indicates marked and ongoing inflammatory reactivity with concomitant neuronal damage. These findings are suggestive of neuronal insult as a result of external factors, rather than some type of developmental mishap. Various xenobiotics have been suggested as possible causes of this pathology. In a recent review, the top ten environmental compounds suspected of causing autism and learning disabilities were listed and they included: lead, methyl-mercury, polychorinated biphenyls, organophosphate pesticides, organochlorine pesticides, endocrine disruptors, automotive exhaust, polycyclic aromatic hydrocarbons, polybrominated diphenyl ethers, and perfluorinated compounds. This current review, however, will focus specifically on mercury exposure and ASD by conducting a comprehensive literature search of original studies in humans that examine the potential relationship between mercury and ASD, categorizing, summarizing, and discussing the published research that addresses this topic. This review found 91 studies that examine the potential relationship between mercury and ASD from 1999 to February 2016. Of these studies, the vast majority (74%) suggest that mercury is a risk factor for ASD, revealing both direct and indirect effects. The preponderance of the evidence indicates that mercury exposure is causal and/or contributory in ASD.

Identification and Treatment of Pathophysiological Comorbidities of Autism Spectrum Disorder to Achieve Optimal Outcomes

Despite the fact that the prevalence of autism spectrum disorder (ASD) continues to rise, no effective medical treatments have become standard of care. In this paper we review some of the pathophysiological abnormalities associated with ASD and their potential associated treatments. Overall, there is evidence for some children with ASD being affected by seizure and epilepsy, neurotransmitter dysfunction, sleep disorders, metabolic abnormalities, including abnormalities in folate, cobalamin, tetrahydrobiopterin, carnitine, redox and mitochondrial metabolism, and immune and gastrointestinal disorders. Although evidence for an association between these pathophysiological abnormalities and ASD exists, the exact relationship to the etiology of ASD and its associated symptoms remains to be further defined in many cases. Despite these limitations, treatments targeting some of these pathophysiological abnormalities have been studied in some cases with high-quality studies, whereas treatments for other pathophysiological abnormalities have not been well studied in many cases. There are some areas of more promising treatments specific for ASD including neurotransmitter abnormalities, particularly imbalances in glutamate and acetylcholine, sleep onset disorder (with behavioral therapy and melatonin), and metabolic abnormalities in folate, cobalamin, tetrahydrobiopterin, carnitine, and redox pathways. There is some evidence for treatments of epilepsy and seizures, mitochondrial and immune disorders, and gastrointestinal abnormalities, particularly imbalances in the enteric microbiome, but further clinical studies are needed in these areas to better define treatments specific to children with ASD. Clearly, there are some promising areas of ASD research that could lead to novel treatments that could become standard of care in the future, but more research is needed to better define subgroups of children with ASD who are affected by specific pathophysiological abnormalities and the optimal treatments for these abnormalities.

Efficacy of Folic Acid Supplementation in Autistic Children Participating in Structured Teaching: An Open-Label Trial

Autism spectrum disorders (ASD) are recognized as a major public health issue. Here, we evaluated the effects of folic acid intervention on methylation cycles and oxidative stress in autistic children enrolled in structured teaching. Sixty-six autistic children enrolled in this open-label trial and participated in three months of structured teaching. Forty-four children were treated with 400 μg folic acid (two times/daily) for a period of three months during their structured teaching (intervention group), while the remaining 22 children were not given any supplement for the duration of the study (control group). The Autism Treatment Evaluation Checklist (ATEC) and Psychoeducational Profile-third edition (PEP-3) were measured at the beginning and end of the treatment period. Folic acid, homocysteine, and glutathione metabolism in plasma were measured before and after treatment in 29 autistic children randomly selected from the intervention group and were compared with 29 age-matched unaffected children (typical developmental group). The results illustrated folic acid intervention improved autism symptoms towards sociability, cognitive verbal/preverbal, receptive language, and affective expression and communication. Furthermore, this treatment also improved the concentrations of folic acid, homocysteine, and normalized glutathione redox metabolism. Folic acid supplementation may have a certain role in the treatment of children with autism.

Mitochondrial Dysfunction may explain symptom variation in Phelan-McDermid Syndrome

Phelan-McDermid Syndrome (PMS), which is defined by a deletion within 22q13, demonstrates significant phenotypic variation. Given that six mitochondrial genes are located within 22q13, including complex I and IV genes, we hypothesize that mitochondrial complex activity abnormalities may explain phenotypic variation in PMS symptoms. Complex I, II, II + III and IV activity was measured in 51 PMS participants. Caretakers completed questionnaires and provided genetic information through the PMS foundation registry. Complex activity was abnormal in 59% of PMS participants. Abnormalities were found in complex I and IV but not complex II + III and II activity, consistent with disruption of genes within the 22q13 region. However, complex activity abnormalities were not related to specific gene deletions suggesting a "neighboring effect" of regional deletions on adjacent gene expression. A specific combination of symptoms (autism spectrum disorder, developmental regression, failure-to-thrive, exercise intolerance/fatigue) was associated with complex activity abnormalities. 64% of 106 individuals in the PMS foundation registry who did not have complex activity measured also endorsed this pattern of symptoms. These data suggest that mitochondrial abnormalities, specifically abnormalities in complex I and IV activity, may explain some phenotypic variation in PMS individuals. These results point to novel pathophysiology mechanisms and treatment targets for PMS patients.

Dysregulated mitochondrial and chloroplast bioenergetics from a translational medical perspective (Review)

Mitochondria and chloroplasts represent endosymbiotic models of complex organelle development, driven by intense evolutionary pressure to provide exponentially enhanced ATP-dependent energy production functionally linked to cellular respiration and photosynthesis. Within the realm of translational medicine, it has become compellingly evident that mitochondrial dysfunction, resulting in compromised cellular bioenergetics, represents a key causative factor in the etiology and persistence of major diseases afflicting human populations. As a pathophysiological consequence of enhanced oxygen utilization that is functionally uncoupled from the oxidative phosphorylation of ADP, significant levels of reactive oxygen species (ROS) may be generated within mitochondria and chloroplasts, which may effectively compromise cellular energy production following prolonged stress/inflammatory conditions. Empirically determined homologies in biochemical pathways, and their respective encoding gene sequences between chloroplasts and mitochondria, suggest common origins via entrapped primordial bacterial ancestors. From evolutionary and developmental perspectives, the elucidation of multiple biochemical and molecular relationships responsible for errorless bioenergetics within mitochondrial and plastid complexes will most certainly enhance the depth of translational approaches to ameliorate or even prevent the destructive effects of multiple disease states. The selective choice of discussion points contained within the present review is designed to provide theoretical bases and translational insights into the pathophysiology of human diseases from a perspective of dysregulated mitochondrial bioenergetics with special reference to chloroplast biology.

Mitochondrial response to the BCKDK-deficiency: Some clues to understand the positive dietary response in this form of autism

Mutations on the mitochondrial-expressed Branched Chain α-Keto acid Dehydrogenase Kinase (BCKDK) gene have been recently associated with a novel dietary-treatable form of autism. But, being a mitochondrial metabolism disease, little is known about the impact on mitochondrial performance. Here, we analyze the mitochondrial response to the BCKDK-deficiency in patient's primary fibroblasts by measuring bioenergetics, ultra-structural and dynamic parameters. A two-fold increase in superoxide anion production, together with a reduction in ATP-linked respiration and intracellular ATP levels (down to 60%) detected in mutants fibroblasts point to a general bioenergetics depletion that could affect the mitochondrial dynamics and cell fate. Ultrastructure analysis of BCKDK-deficient fibroblasts shows an increased number of elongated mitochondria, apparently associated with changes in the mediator of inner mitochondria membrane fusion, GTPase OPA1 forms, and in the outer mitochondrial membrane, mitofusin 2/MFN2. Our data support a possible hyperfusion response of BCKDK-deficient mitochondria to stress. Cellular fate also seems to be affected as these fibroblasts show an altered proportion of the cells on G0/G1 and G2/M phases. Knockdown of BCKDK gene in control fibroblasts recapitulates most of these features. Same BCKDK-knockdown in a MSUD patient fibroblasts unmasks the direct involvement of the accelerated BCAAs catabolism in the mitochondrial dysfunction. All these data give us a clue to understand the positive dietary response to an overload of branched-chain amino acids. We hypothesize that a combination of the current therapeutic option with a protocol that considers the oxidative damage and energy expenditure, addressing the patients' individuality, might be useful for the physicians.

Mitochondrial enzyme dysfunction in autism spectrum disorders; a novel biomarker revealed from buccal swab analysis

AIM

Mitochondrial function studies in autism spectrum disorders (ASD) have detected skeletal muscle mitochondrial enzyme deficiencies in respiratory complex (RC) activities. As a muscle biopsy is expensive and invasive, we assessed RC-I and RC-IV activities in buccal swabs.

METHODS

92 children with ASD and 68 controls were studied with immunocapture for RC-I and microspectrophotometry for RC-IV.

RESULTS

Significant RC activity deficiencies were found in 39 (42%) ASD patients (p < 0.01) and more prevalent in more severe cases. Aberrant RC overactivity was seen in 9 children. RC-I/RC-IV activity ratio was significantly increased in 64% of the entire ASD cohort including 76% of those more severely affected (p < 0.05).

CONCLUSION

Buccal swab analysis revealed extensive RC abnormalities in ASD providing a noninvasive biomarker to assess mitochondrial function in ASD patients.

Autism in the Son of a Woman with Mitochondrial Myopathy and Dysautonomia: A Case Report

The relationship between autism spectrum disorders and mitochondrial dysfunction, including mitochondrial myopathies and other mitochondrial diseases, is an area of ongoing research. All autism spectrum disorders are known to be heritable, via genetic and/or epigenetic mechanisms, but specific modes of inheritance are not well characterized. Nevertheless, autism spectrum disorders have been linked to many specific genes associated with mitochondrial function, especially to genes involved in mitochondrial tRNA and the electron transport chain, both particularly vulnerable to point mutations, and clinical research also supports a relationship between the two pathologies. Although only a small minority of patients with autism have a mitochondrial disease, many patients with mitochondrial myopathies have autism spectrum disorder symptoms, and these symptoms may be the presenting symptoms, which presents a diagnostic challenge for clinicians. The authors report the case of a 15-year-old boy with a history of autism spectrum disorder and neurocardiogenic syncope, admitted to the inpatient unit for self-injury, whose young mother, age 35, was discovered to suffer from mitochondrial myopathy, dysautonomia, neurocardiogenic syncope, Ehler-Danlos syndrome, and other uncommon multisystem pathologies likely related to mitochondrial dysfunction. This case illustrates the need for a high index of suspicion for mitochondrial disease in patients with autism, as they have two orders of magnitude greater risk for such diseases than the general population. The literature shows that mitochondrial disease is underdiagnosed in autism spectrum disorder patients and should not be viewed as a "zebra" (i.e., an obscure diagnosis that is made when a more common explanation is more likely).

Alterations in the Vaginal Microbiome by Maternal Stress Are Associated With Metabolic Reprogramming of the Offspring Gut and Brain

The neonate is exposed to the maternal vaginal microbiota during parturition, providing the primary source for normal gut colonization, host immune maturation, and metabolism. These early interactions between the host and microbiota occur during a critical window of neurodevelopment, suggesting early life as an important period of cross talk between the developing gut and brain. Because perturbations in the prenatal environment such as maternal stress increase neurodevelopmental disease risk, disruptions to the vaginal ecosystem could be a contributing factor in significant and long-term consequences for the offspring. Therefore, to examine the hypothesis that changes in the vaginal microbiome are associated with effects on the offspring gut microbiota and on the developing brain, we used genomic, proteomic and metabolomic technologies to examine outcomes in our mouse model of early prenatal stress. Multivariate modeling identified broad proteomic changes to the maternal vaginal environment that influence offspring microbiota composition and metabolic processes essential for normal neurodevelopment. Maternal stress altered proteins related to vaginal immunity and abundance of Lactobacillus, the prominent taxa in the maternal vagina. Loss of maternal vaginal Lactobacillus resulted in decreased transmission of this bacterium to offspring. Further, altered microbiota composition in the neonate gut corresponded with changes in metabolite profiles involved in energy balance, and with region- and sex-specific disruptions of amino acid profiles in the developing brain. Taken together, these results identify the vaginal microbiota as a novel factor by which maternal stress may contribute to reprogramming of the developing brain that may predispose individuals to neurodevelopmental disorders.

Metabolic and mitochondrial disorders associated with epilepsy in children with autism spectrum disorder

Autism spectrum disorder (ASD) affects a significant number of individuals in the United States, with the prevalence continuing to grow. A significant proportion of individuals with ASD have comorbid medical conditions such as epilepsy. In fact, treatment-resistant epilepsy appears to have a higher prevalence in children with ASD than in children without ASD, suggesting that current antiepileptic treatments may be suboptimal in controlling seizures in many individuals with ASD. Many individuals with ASD also appear to have underlying metabolic conditions. Metabolic conditions such as mitochondrial disease and dysfunction and abnormalities in cerebral folate metabolism may affect a substantial number of children with ASD, while other metabolic conditions that have been associated with ASD such as disorders of creatine, cholesterol, pyridoxine, biotin, carnitine, γ-aminobutyric acid, purine, pyrimidine, and amino acid metabolism and urea cycle disorders have also been associated with ASD without the prevalence clearly known. Interestingly, all of these metabolic conditions have been associated with epilepsy in children with ASD. The identification and treatment of these disorders could improve the underlying metabolic derangements and potentially improve behavior and seizure frequency and/or severity in these individuals. This paper provides an overview of these metabolic disorders in the context of ASD and discusses their characteristics, diagnostic testing, and treatment with concentration on mitochondrial disorders. To this end, this paper aims to help optimize the diagnosis and treatment of children with ASD and epilepsy. This article is part of a Special Issue entitled "Autism and Epilepsy".

Enteric short-chain fatty acids: microbial messengers of metabolism, mitochondria, and mind: implications in autism spectrum disorders

Clinical observations suggest that gut and dietary factors transiently worsen and, in some cases, appear to improve behavioral symptoms in a subset of persons with autism spectrum disorders (ASDs), but the reason for this is unclear. Emerging evidence suggests ASDs are a family of systemic disorders of altered immunity, metabolism, and gene expression. Pre- or perinatal infection, hospitalization, or early antibiotic exposure, which may alter gut microbiota, have been suggested as potential risk factors for ASD. Can a common environmental agent link these disparate findings? This review outlines basic science and clinical evidence that enteric short-chain fatty acids (SCFAs), present in diet and also produced by opportunistic gut bacteria following fermentation of dietary carbohydrates, may be environmental triggers in ASD. Of note, propionic acid, a major SCFA produced by ASD-associated gastrointestinal bacteria (clostridia, bacteroides, desulfovibrio) and also a common food preservative, can produce reversible behavioral, electrographic, neuroinflammatory, metabolic, and epigenetic changes closely resembling those found in ASD when administered to rodents. Major effects of these SCFAs may be through the alteration of mitochondrial function via the citric acid cycle and carnitine metabolism, or the epigenetic modulation of ASD-associated genes, which may be useful clinical biomarkers. It discusses the hypothesis that ASDs are produced by pre- or post-natal alterations in intestinal microbiota in sensitive sub-populations, which may have major implications in ASD cause, diagnosis, prevention, and treatment.

Prenatal factors associated with autism spectrum disorder (ASD)

Autism spectrum disorder (ASD) affecting about 1% of all children is associated, in addition to complex genetic factors, with a variety of prenatal, perinatal and postnatal etiologies. We discuss the known associated prenatal factors affecting the fetus throughout pregnancy; whenever relevant, also summarize some animal data. Among the maternal diseases in pregnancy associated with ASD are pregestational and/or gestational diabetes mellitus (PGDM, GDM), maternal infections (i.e. rubella, cytomegalovirus (CMV)), prolonged fever and maternal inflammation, which cause changes in a variety of inflammatory cytokines. Among the drugs are valproic acid, thalidomide, and possibly misoprostol and serotonin reuptake inhibitors (SSRIs). Associations were described with ethanol, and possibly cocaine, heavy metals heavy smoking and Folic acid deficiency. Heavy exposure to pesticides and air pollution during pregnancy was recently associated with ASD. We need more epidemiologic data to establish many of these associations; if proven, they might be promising avenues for prevention.

Gastrointestinal dysfunction in autism spectrum disorder: the role of the mitochondria and the enteric microbiome

Autism spectrum disorder (ASD) affects a significant number of individuals worldwide with the prevalence continuing to grow. It is becoming clear that a large subgroup of individuals with ASD demonstrate abnormalities in mitochondrial function as well as gastrointestinal (GI) symptoms. Interestingly, GI disturbances are common in individuals with mitochondrial disorders and have been reported to be highly prevalent in individuals with co-occurring ASD and mitochondrial disease. The majority of individuals with ASD and mitochondrial disorders do not manifest a primary genetic mutation, raising the possibility that their mitochondrial disorder is acquired or, at least, results from a combination of genetic susceptibility interacting with a wide range of environmental triggers. Mitochondria are very sensitive to both endogenous and exogenous environmental stressors such as toxicants, iatrogenic medications, immune activation, and metabolic disturbances. Many of these same environmental stressors have been associated with ASD, suggesting that the mitochondria could be the biological link between environmental stressors and neurometabolic abnormalities associated with ASD. This paper reviews the possible links between GI abnormalities, mitochondria, and ASD. First, we review the link between GI symptoms and abnormalities in mitochondrial function. Second, we review the evidence supporting the notion that environmental stressors linked to ASD can also adversely affect both mitochondria and GI function. Third, we review the evidence that enteric bacteria that are overrepresented in children with ASD, particularly Clostridia spp., produce short-chain fatty acid metabolites that are potentially toxic to the mitochondria. We provide an example of this gut–brain connection by highlighting the propionic acid rodent model of ASD and the clinical evidence that supports this animal model. Lastly, we discuss the potential therapeutic approaches that could be helpful for GI symptoms in ASD and mitochondrial disorders. To this end, this review aims to help better understand the underlying pathophysiology associated with ASD that may be related to concurrent mitochondrial and GI dysfunction.

Modulation of the genome and epigenome of individuals susceptible to autism by environmental risk factors

Diverse environmental factors have been implicated with the development of autism spectrum disorders (ASD). Genetic factors also underlie the differential vulnerability to environmental risk factors of susceptible individuals. Currently the way in which environmental risk factors interact with genetic factors to increase the incidence of ASD is not well understood. A greater understanding of the metabolic, cellular, and biochemical events involved in gene x environment interactions in ASD would have important implications for the prevention and possible treatment of the disorder. In this review we discuss various established and more alternative processes through which environmental factors implicated in ASD can modulate the genome and epigenome of genetically-susceptible individuals.

The many roads to mitochondrial dysfunction in neuroimmune and neuropsychiatric disorders

BACKGROUND

Mitochondrial dysfunction and defects in oxidative metabolism are a characteristic feature of many chronic illnesses not currently classified as mitochondrial diseases. Examples of such illnesses include bipolar disorder, multiple sclerosis, Parkinson's disease, schizophrenia, depression, autism, and chronic fatigue syndrome.

DISCUSSION

While the majority of patients with multiple sclerosis appear to have widespread mitochondrial dysfunction and impaired ATP production, the findings in patients diagnosed with Parkinson's disease, autism, depression, bipolar disorder schizophrenia and chronic fatigue syndrome are less consistent, likely reflecting the fact that these diagnoses do not represent a disease with a unitary pathogenesis and pathophysiology. However, investigations have revealed the presence of chronic oxidative stress to be an almost invariant finding in study cohorts of patients afforded each diagnosis. This state is characterized by elevated reactive oxygen and nitrogen species and/or reduced levels of glutathione, and goes hand in hand with chronic systemic inflammation with elevated levels of pro-inflammatory cytokines.

SUMMARY

This paper details mechanisms by which elevated levels of reactive oxygen and nitrogen species together with elevated pro-inflammatory cytokines could conspire to pave a major road to the development of mitochondrial dysfunction and impaired oxidative metabolism seen in many patients diagnosed with these disorders.

An n=1 case report of a child with autism improving on antibiotics and a father's quest to understand what it may mean

The author, a parent of a child with autism, describes an n=1 case in which his child's autism symptoms dramatically and rapidly improved following administration of a common antibiotic. The author asserts that this finding is not unusual in the autism population and that, when combined with prior recent medical research, suggests that a link between autism and the microbiome in some children is not just plausible, but in fact likely for some meaningful percentage of cases. The author argues for increased funding for a more thorough examination of links between autism and the microbiome and poses a series of questions to be further examined in future research.

Zinc in gut-brain interaction in autism and neurological disorders

A growing amount of research indicates that abnormalities in the gastrointestinal (GI) system during development might be a common factor in multiple neurological disorders and might be responsible for some of the shared comorbidities seen among these diseases. For example, many patients with Autism Spectrum Disorder (ASD) have symptoms associated with GI disorders. Maternal zinc status may be an important factor given the multifaceted effect of zinc on gut development and morphology in the offspring. Zinc status influences and is influenced by multiple factors and an interdependence of prenatal and early life stress, immune system abnormalities, impaired GI functions, and zinc deficiency can be hypothesized. In line with this, systemic inflammatory events and prenatal stress have been reported to increase the risk for ASD. Thus, here, we will review the current literature on the role of zinc in gut formation, a possible link between gut and brain development in ASD and other neurological disorders with shared comorbidities, and tie in possible effects on the immune system. Based on these data, we present a novel model outlining how alterations in the maternal zinc status might pathologically impact the offspring leading to impairments in brain functions later in life.

Cancer metabolism and oxidative stress: Insights into carcinogenesis and chemotherapy via the non-dihydrofolate reductase effects of methotrexate

Methotrexate has been in use as an anti-cancer agent for over 60 years. Though inhibition of dihydrofolate reductase is its best known mechanisms of action, its non-dihydrofolate reductase dependent mechanisms disrupt metabolic pathways resulting in a depletion of NAD(P)H and increasing oxidative stress. These mechanisms highlight a novel dependence of cancer cells on their metabolic abnormalities to buffer oxidative stress and chemotherapeutic agents interfere with these cellular abilities. Mitochondria appear to play a significant role in maintaining cancer cell viability and alterations in metabolism seen in cancer cells aid this mitochondrial ability. Further research is needed to understand the effects of other chemotherapeutic agents on these pathways.

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Methotrexate inhibits multiple enzymes beyond dihydrofolate reductase.

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Mitochondria serve a critical role in buffering cellular oxidative stress.

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Metabolic derangements seen in cancer fuel this mitochondrial rescue function.

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Methotrexate toxicity occurs secondary to a handicapping of this buffering function.

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Many chemotherapeutic agents appear to have mechanisms affecting these pathways.

Glutathione redox imbalance in brain disorders

PURPOSE OF REVIEW

Glutathione (GSH) is a major endogenous antioxidant. Several studies have implicated GSH redox imbalance in brain disorders. Here, we summarize current evidence on how GSH depletion and GSH-related enzyme deficit are involved in the pathology of brain disorders such as autism, schizophrenia, bipolar disorder, Alzheimer's disease, and Parkinson's disease.

RECENT FINDINGS

Many studies with animal models of various brain disorders and/or with clinical samples from humans with neurodegenerative and neuropsychiatric disorders have demonstrated altered levels of GSH and oxidized glutathione (GSSG), decreased ratio of GSH/GSSG, and/or impaired expressions or activities of GSH-related enzymes in the blood or brain of these individuals. GSH depletion can lead to abnormalities in methylation metabolism and mitochondrial function. A few studies showed that a GSH deficit occurs prior to neuropathological abnormalities in these diseases. The potential therapeutic agents for brain disorders include N-acetylcysteine, liposomes encapsulated with GSH, and whey protein supplement, which can increase the GSH levels in the brain and alleviate oxidative stress-associated damage and may improve the behavior of individuals with brain diseases.

SUMMARY

GSH plays an important role during the onset and progression of neuropsychiatric and neurodegenerative diseases. GSH redox imbalance may be a primary cause of these brain disorders and may be used as a biomarker for diagnosis of these diseases. N-acetylcysteine and other agents that can increase the concentration of GSH in the brain are promising approaches for the treatment of these brain disorders.

Metabolic pathology of autism in relation to redox metabolism

An imbalance in glutathione-dependent redox metabolism has been shown to be associated with autism spectrum disorder (ASD). Glutathione synthesis and intracellular redox balance are linked to folate and methylation metabolism, metabolic pathways that have also been shown to be abnormal in ASD. Together, these metabolic abnormalities define a distinct ASD endophenotype that is closely associated with genetic, epigenetic and mitochondrial abnormalities, as well as environmental factors related to ASD. Biomarkers that reflect these metabolic abnormalities will be discussed in the context of an ASD metabolic endophenotype that may lead to a better understanding of the pathophysiological mechanisms underlying core and associated ASD symptoms. Last, we discuss how these biomarkers have been used to guide the development of novel ASD treatments.

Pathologies in functional connectivity, feedback control and robustness: a global workspace perspective on autism spectrum disorders

We study the background to problems of functional connectivity in autism spectrum disorders within the neurocognitive framework of the global workspace model. This we proceed to do by observing network irregularities detracting from that of a well-formed small world network architecture. This is discussed in terms of pathologies in functional connectivity and lack of central coherence disrupting inter-network communication thus impairing effective cognitive action. A typical coherence-connectivity measure as a by-product of various neuroimaging results is considered. This is related to a model of feedback control in which a coherence function in the frequency domain is modified by an environmentally determined interaction parameter. With respect to the latter, we discuss the stability question that in theory may counterbalance inessential metabolic costs and incoherence of processing. We suggest that factors such as local overconnectivity and global underconnectivity, along with acute over-expenditure of metabolic costs give rise to instability within the connective core of the workspace.

Treatments for biomedical abnormalities associated with autism spectrum disorder

Recent studies point to the effectiveness of novel treatments that address physiological abnormalities associated with autism spectrum disorder (ASD). This is significant because safe and effective treatments for ASD remain limited. These physiological abnormalities as well as studies addressing treatments of these abnormalities are reviewed in this article. Treatments commonly used to treat mitochondrial disease have been found to improve both core and associated ASD symptoms. Double-blind, placebo-controlled (DBPC) studies have investigated l-carnitine and a multivitamin containing B vitamins, antioxidants, vitamin E, and co-enzyme Q10 while non-blinded studies have investigated ubiquinol. Controlled and uncontrolled studies using folinic acid, a reduced form of folate, have reported marked improvements in core and associated ASD symptoms in some children with ASD and folate related pathway abnormities. Treatments that could address redox metabolism abnormalities include methylcobalamin with and without folinic acid in open-label studies and vitamin C and N-acetyl-l-cysteine in DBPC studies. These studies have reported improved core and associated ASD symptoms with these treatments. Lastly, both open-label and DBPC studies have reported improvements in core and associated ASD symptoms with tetrahydrobiopterin. Overall, these treatments were generally well-tolerated without significant adverse effects for most children, although we review the reported adverse effects in detail. This review provides evidence for potentially safe and effective treatments for core and associated symptoms of ASD that target underlying known physiological abnormalities associated with ASD. Further research is needed to define subgroups of children with ASD in which these treatments may be most effective as well as confirm their efficacy in DBPC, large-scale multicenter studies.

Evidence linking oxidative stress, mitochondrial dysfunction, and inflammation in the brain of individuals with autism

Autism spectrum disorders (ASDs) are a heterogeneous group of neurodevelopmental disorders that are defined solely on the basis of behavioral observations. Therefore, ASD has traditionally been framed as a behavioral disorder. However, evidence is accumulating that ASD is characterized by certain physiological abnormalities, including oxidative stress, mitochondrial dysfunction and immune dysregulation/inflammation. While these abnormalities have been reported in studies that have examined peripheral biomarkers such as blood and urine, more recent studies have also reported these abnormalities in brain tissue derived from individuals diagnosed with ASD as compared to brain tissue derived from control individuals. A majority of these brain tissue studies have been published since 2010. The brain regions found to contain these physiological abnormalities in individuals with ASD are involved in speech and auditory processing, social behavior, memory, and sensory and motor coordination. This manuscript examines the evidence linking oxidative stress, mitochondrial dysfunction and immune dysregulation/inflammation in the brain of ASD individuals, suggesting that ASD has a clear biological basis with features of known medical disorders. This understanding may lead to new testing and treatment strategies in individuals with ASD.

Biomarkers in autism

Autism spectrum disorders (ASDs) are complex, heterogeneous disorders caused by an interaction between genetic vulnerability and environmental factors. In an effort to better target the underlying roots of ASD for diagnosis and treatment, efforts to identify reliable biomarkers in genetics, neuroimaging, gene expression, and measures of the body's metabolism are growing. For this article, we review the published studies of potential biomarkers in autism and conclude that while there is increasing promise of finding biomarkers that can help us target treatment, there are none with enough evidence to support routine clinical use unless medical illness is suspected. Promising biomarkers include those for mitochondrial function, oxidative stress, and immune function. Genetic clusters are also suggesting the potential for useful biomarkers.

ROS and brain diseases: the good, the bad, and the ugly

The brain is a major metabolizer of oxygen and yet has relatively feeble protective antioxidant mechanisms. This paper reviews the Janus-faced properties of reactive oxygen species. It will describe the positive aspects of moderately induced ROS but it will also outline recent research findings concerning the impact of oxidative and nitrooxidative stress on neuronal structure and function in neuropsychiatric diseases, including major depression. A common denominator of all neuropsychiatric diseases including schizophrenia and ADHD is an increased inflammatory response of the brain caused either by an exposure to proinflammatory agents during development or an accumulation of degenerated neurons, oxidized proteins, glycated products, or lipid peroxidation in the adult brain. Therefore, modulation of the prooxidant-antioxidant balance provides a therapeutic option which can be used to improve neuroprotection in response to oxidative stress. We also discuss the neuroprotective role of the nuclear factor erythroid 2-related factor (Nrf2) in the aged brain in response to oxidative stressors and nanoparticle-mediated delivery of ROS-scavenging drugs. The antioxidant therapy is a novel therapeutic strategy. However, the available drugs have pleiotropic actions and are not fully characterized in the clinic. Additional clinical trials are needed to assess the risks and benefits of antioxidant therapies for neuropsychiatric disorders.

Effectiveness of methylcobalamin and folinic Acid treatment on adaptive behavior in children with autistic disorder is related to glutathione redox status

Treatments targeting metabolic abnormalities in children with autism are limited. Previously we reported that a nutritional treatment significantly improved glutathione metabolism in children with autistic disorder. In this study we evaluated changes in adaptive behaviors in this cohort and determined whether such changes are related to changes in glutathione metabolism. Thirty-seven children diagnosed with autistic disorder and abnormal glutathione and methylation metabolism were treated with twice weekly 75 µg/Kg methylcobalamin and twice daily 400 µg folinic acid for 3 months in an open-label fashion. The Vineland Adaptive Behavior Scale (VABS) and glutathione redox metabolites were measured at baseline and at the end of the treatment period. Over the treatment period, all VABS subscales significantly improved with an average effect size of 0.59, and an average improvement in skills of 7.7 months. A greater improvement in glutathione redox status was associated with a greater improvement in expressive communication, personal and domestic daily living skills, and interpersonal, play-leisure, and coping social skills. Age, gender, and history of regression did not influence treatment response. The significant behavioral improvements observed and the relationship between these improvements to glutathione redox status suggest that nutritional interventions targeting redox metabolism may benefit some children with autism.

Mitochondrial dysfunction in autism

Using data of the current prevalence of autism as 200:10,000 and a 1:2000 incidence of definite mitochondrial (mt) disease, if there was no linkage of autism spectrum disorder (ASD) and mt disease, it would be expected that 1 in 110 subjects with mt disease would have ASD and 1 in 2000 individuals with ASD would have mt disease. The co-occurrence of autism and mt disease is much higher than these figures, suggesting a possible pathogenetic relationship. Such hypothesis was initially suggested by the presence of biochemical markers of abnormal mt metabolic function in patients with ASD, including elevation of lactate, pyruvate, or alanine levels in blood, cerebrospinal fluid, or brain; carnitine level in plasma; and level of organic acids in urine, and by demonstrating impaired mt fatty acid β-oxidation. More recently, mtDNA genetic mutations or deletions or mutations of nuclear genes regulating mt function have been associated with ASD in patients or in neuropathologic studies on the brains of patients with autism. In addition, the presence of dysfunction of the complexes of the mt respiratory chain or electron transport chain, indicating abnormal oxidative phosphorylation, has been reported in patients with ASD and in the autopsy samples of brains. Possible pathogenetic mechanisms linking mt dysfunction and ASD include mt activation of the immune system, abnormal mt Ca(2+) handling, and mt-induced oxidative stress. Genetic and epigenetic regulation of brain development may also be disrupted by mt dysfunction, including mt-induced oxidative stress. The role of the purinergic system linking mt dysfunction and ASD is currently under investigation. In summary, there is genetic and biochemical evidence for a mitochondria (mt) role in the pathogenesis of ASD in a subset of children. To determine the prevalence and type of genetic and biochemical mt defects in ASD, there is a need for further research using the latest genetic technology such as next-generation sequencing, microarrays, bioinformatics, and biochemical assays. Because of the availability of potential therapeutic options for mt disease, successful research results could translate into better treatment and outcome for patients with mt-associated ASD. This requires a high index of suspicion of mt disease in children with autism who are diagnosed early.