Oxidative Stress In Autism

Advances in Autism Research
April 2010

Increased oxidative stress is reported in autism and has both etiologic and clinical significance. Two older studies start the citations listed in this section. Citations with a blue title link directly to Pubmed. Some are free online.

1. Metabolic biomarkers of increased oxidative stress and impaired methylation capacity in children with autism
James SJ, Cutler P, Melnyk S, Jernigan S, Janak L, Gaylor DW, Neubrander JA.
Am J Clin Nutr. 2004 Dec;80(6):1611-7.
http://www.ajcn.org/cgi/content/full/80/6/1611

BACKGROUND: Autism is a complex neurodevelopmental disorder that usually presents in early childhood and that is thought to be influenced by genetic and environmental factors. Although abnormal metabolism of methionine and homocysteine has been associated with other neurologic diseases, these pathways have not been evaluated in persons with autism. OBJECTIVE: The purpose of this study was to evaluate plasma concentrations of metabolites in the methionine transmethylation and transsulfuration pathways in children diagnosed with autism. DESIGN: Plasma concentrations of methionine, S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), adenosine, homocysteine, cystathionine, cysteine, and oxidized and reduced glutathione were measured in 20 children with autism and in 33 control children. On the basis of the abnormal metabolic profile, a targeted nutritional intervention trial with folinic acid, betaine, and methylcobalamin was initiated in a subset of the autistic children. RESULTS: Relative to the control children, the children with autism had significantly lower baseline plasma concentrations of methionine, SAM, homocysteine, cystathionine, cysteine, and total glutathione and significantly higher concentrations of SAH, adenosine, and oxidized glutathione. This metabolic profile is consistent with impaired capacity for methylation (significantly lower ratio of SAM to SAH) and increased oxidative stress (significantly lower redox ratio of reduced glutathione to oxidized glutathione) in children with autism. The intervention trial was effective in normalizing the metabolic imbalance in the autistic children. CONCLUSIONS: An increased vulnerability to oxidative stress and a decreased capacity for methylation may contribute to the development and clinical manifestation of autism.

2. Oxidative stress in autism
McGinnis WR.
Altern Ther Health Med. 2004 Nov-Dec;10(6):22-36;
http://www.ncbi.nlm.nih.gov/pubmed/15624347

STATEMENT OF PURPOSE: Indirect markers are consistent with greater oxidative stress in autism. They include greater free-radical production, impaired energetics and cholinergics, and higher excitotoxic markers. Brain and gut, both abnormal in autism, are particularly sensitive to oxidative injury. Higher red-cell lipid peroxides and urinary isoprostanes in autism signify greater oxidative damage to biomolecules. A preliminary study found accelerated lipofuscin deposition--consistent with oxidative injury to autistic brain in cortical areas serving language and communication. Double-blind, placebo-controlled trials of potent antioxidants--vitamin C or carnosine--significantly improved autistic behavior. Benefits from these and other nutritional interventions may be due to reduction of oxidative stress. Understanding the role of oxidative stress may help illuminate the pathophysiology of autism, its environmental and genetic influences, new treatments, and prevention. OBJECTIVES: Upon completion of this article, participants should be able to: 1. Be aware of laboratory and clinical evidence of greater oxidative stress in autism. 2. Understand how gut, brain, nutritional, and toxic status in autism are consistent with greater oxidative stress. 3. Describe how anti-oxidant nutrients are used in the contemporary treatment of autism.

3. Oxidative stress in psychiatric disorders: evidence base and therapeutic implications.
Ng F, Berk M, Dean O, Bush AI.
Int J Neuropsychopharmacol. 2008 Sep;11(6):851-76.

4. How environmental and genetic factors combine to cause autism: A redox/methylation hypothesis.
Deth R, Muratore C, Benzecry J, Power-Charnitsky VA, Waly M.
Neurotoxicology. 2008 Jan;29(1):190-201

5 . Plasma concentrations of selected antioxidants in autistic children and adolescents
Krajcovicova-Kudlackova M et al.
Slovak Medical University
Bratisl Lek Listy. 2009;110(4):247-50.
http://www.bmj.sk/2009/11004-09.pdf

Few studies have demonstrated an increased vulnerability to oxidative stress in autism. The results of previous studies have shown that endogenous antioxidant defence is insufficient, indicating that exogenous antioxidant could play a crucial role for oxidative stress prevention in autism. Plasma concentrations of vitamins C, E, A, carotenoids beta-carotene and lycopene were measured in 51 subjects with autistic spectrum disorders aged 5-18 years (27 children aged 5-10 years, 24 subjects aged 11-18 years). Older autistic group was compared with a group of healthy Slovak subjects aged 11-18 years. Older autistic subjects vs. healthy control showed significantly higher vitamin C and beta-carotene plasma values with 92% and 71% vs 54% and 13% of optimal over-threshold values, respectively. This indicates a reduced risk of free radical disease. In younger vs. older autistic group the similarly high plasma vitamin concentrations were recorded. Favourable values of these vitamins suggested that consumption of fruit and vegetables in autistic subjects is optimal. Autistic average vitamin E and A plasma concentrations (non-significantly changed in comparison to control group) were below-threshold with low percentage of over-threshold values. Insufficient vitamin E and A plasma values indicate lower consumption of food rich in vitamins A and E (e.g. whole-grain products, plant oils, oil seeds, nuts, fat spreads and dairy products). Autistic average lycopene concentration is lower in comparison to published non-Slovak data. Conclusions of this pilot study suggest that plasma concentrations of exogenous antioxidants, vitamins E and A, and lycopene in autistic subjects are insufficient (Tab. 1, Ref. 30).

6. Mercury exposure, nutritional deficiencies and metabolic disruptions may affect learning in children
Dufault R, Schnoll R, Lukiw WJ, Leblanc B, Cornett C, Patrick L, Wallinga D, Gilbert SG, Crider R.
Behav Brain Funct. 2009 Oct 27;5:44.
http://www.behavioralandbrainfunctions.com/content/5/1/44

ABSTRACT: Among dietary factors, learning and behavior are influenced not only by nutrients, but also by exposure to toxic food contaminants such as mercury that can disrupt metabolic processes and alter neuronal plasticity. Neurons lacking in plasticity are a factor in neurodevelopmental disorders such as autism and mental retardation. Essential nutrients help maintain normal neuronal plasticity. Nutritional deficiencies, including deficiencies in the long chain polyunsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid, the amino acid methionine, and the trace minerals zinc and selenium, have been shown to influence neuronal function and produce defects in neuronal plasticity, as well as impact behavior in children with attention deficit hyperactivity disorder. Nutritional deficiencies and mercury exposure have been shown to alter neuronal function and increase oxidative stress among children with autism. These dietary factors may be directly related to the development of behavior disorders and learning disabilities. Mercury, either individually or in concert with other factors, may be harmful if ingested in above average amounts or by sensitive individuals. High fructose corn syrup has been shown to contain trace amounts of mercury as a result of some manufacturing processes, and its consumption can also lead to zinc loss. Consumption of certain artificial food color additives has also been shown to lead to zinc deficiency. Dietary zinc is essential for maintaining the metabolic processes required for mercury elimination. Since high fructose corn syrup and artificial food color additives are common ingredients in many foodstuffs, their consumption should be considered in those individuals with nutritional deficits such as zinc deficiency or who are allergic or sensitive to the effects of mercury or unable to effectively metabolize and eliminate it from the body.

7. Sera from children with autism alter proliferation of human neuronal progenitor cells exposed to oxidation
Mazur-Kolecka B et al.
NYS Institute for Basic Research in Developmental Disabilities
Neurotox Res. 2009 Jul;16(1):87-95. Epub 2009 Apr 18.
$ http://www.springerlink.com/content/y0pnw64733x02vg7/

Altered brain development during embryogenesis and early postnatal life has been hypothesized to be responsible for the abnormal behaviors of people with autism. The specific genetic background that alters vulnerability to some environmental insults has been suggested in the etiology of autism; however, the specific pathomechanisms have not been identified. Recently, we showed that sera from children with autism alter the maturation of human neuronal progenitor cells (NPCs) in culture. Results suggest that pre-programmed neurogenesis, i.e., neuronal proliferation, migration, differentiation, growth, and circuit organization, can be affected differently by factors present in autistic sera. In this report, we tested the effect of autistic sera on the vulnerability of NPCs to oxidative stress-a recognized risk factor of autism. We found that mild oxidative stress reduced proliferation of differentiating NPCs but not immature NPCs. This decrease of proliferation was less prominent in cultures treated with sera from children with autism than from age-matched controls. These results suggest that altered response of NPCs to oxidative stress may play a role in the etiology of autism.

8. Measurement of selected ions related to oxidative stress and energy metabolism in Saudi autistic children
El-Ansary A et al.
Clin Biochem. 2009 Sep 23. [Epub ahead of print]
$ http://tinyurl.com/yejsxeu

OBJECTIVES:: Autism is a developmental disorder characterized by social and emotional deficits, language impairments and stereotyped behaviors that manifest in early postnatal life. This study aims to clarify the role of selected ions related to energy metabolism as a consequence of oxidative stress in the deterioration accompanied autism. MATERIALS AND METHODS:: Malonaldehyde as measure of lipid peroxidation, Na(+)/K(+) ion pump (ATPase), together with the concentrations of Na(+), K(+), Mg(2+), Ca(2+) and Pb(2+) were determined in plasma of 30 Saudi autistic patients and compared to 30 age-matching control samples. RESULTS:: The obtained data recorded that Saudi autistic patients have a remarkable higher activities of Na(+)/K(+) ATPase and high levels of lipid peroxidation compared to control. In addition, they have significantly elevated levels of K(+) and Pb(2+) while Ca(2+) recorded a significantly lower level compared to age-matching control subjects. On the other hand both Mg(2+) and Na(+) were non-significantly changed in autistic patients. CONCLUSION:: Alteration of the selected measured ions confirms that oxidative stress and defective mitochondrial energy production could represent the primary causative factor in the pathogenesis of autism.

9. Oxidative stress in Egyptian children with autism: relation to autoimmunity
Mostafa GA, El-Hadidi ES, Hewedi DH, Abdou MM.
J Neuroimmunol. 2009 Dec 23. [Epub ahead of print]
$ http://tinyurl.com/ybmx3y4

We are the first to study the relationship between oxidative stress (by measuring plasma F2-isoprostane, as a marker of lipid peroxidation, and glutathione peroxidase, as an antioxidant enzyme) and autoimmunity (as indicated by serum antineuronal antibodies) in a group of 44 Egyptian autistic children and 44 healthy matched-children. Our results showed that oxidative stress was found in 88.64% of autistic children. Oxidative stress, resulting from elevated plasma F2-isoprostane and/or reduced glutathione peroxidase, had significant risk for antineuronal positivity, which was found in 54.5% of autistic children, (odds ratio: 12.38 and 6.43, respectively, confidence interval: 1.37-112.10 and 1.21-34.19, respectively). Conclusions: the strong association between oxidative stress and autoimmunity in autistic children may indicate the possible role of oxidative stress, through induction of autoimmunity, in some autistic patients. Therefore, studies considering the role of antioxidants and immunotherapy in amelioration of autistic manifestations are recommended.

10. Increased Copper-Mediated Oxidation of Membrane Phosphatidylethanolamine in Autism
Abha Chauhan, Ashfaq M. Sheikh and Ved Chauhan
American Journal of Biochemistry and Biotechnology 4(2): 95-100, 2008
http://www.scipub.org/fulltext/ajbb/ajbb4295-100.pdf

We have previously reported that levels of phosphatidylethanolamine (PE) in the erythrocyte membrane and of ceruloplasmin, a copper-transport antioxidant protein, in the serum are lower in children with autism than in control subjects. In the present study, we report that (a) copper oxidizes and reduces the levels of membrane PE and (b) copper-mediated oxidation of PE is higher in lymphoblasts from autistic subjects than from control subjects. The effect of copper was examined on the oxidation of liposomes composed of brain lipids from mice and also on the lymphoblasts from autism and control subjects. Among the various metal cations (copper, iron, calcium, cadmium and zinc), only copper was found to oxidize and decrease the levels of PE. The metal cations did not affect the levels of other phospholipids. The action of copper on PE oxidation was time-dependent and concentration-dependent. No difference was observed between copper-mediated oxidation of diacyl-PE and alkenyl-PE (plasmalogen), suggesting that plasmalogenic and non-plasmalogenic PE are equally oxidized by copper. Together, these studies suggest that ceruloplasmin and copper may contribute to oxidative stress and to reduced levels of membrane PE in autism.

11. Oxidative Stress in Autism: Elevated Cerebellar 3-nitrotyrosine Levels
Elizabeth M. Sajdel-Sulkowska, Boguslaw Lipinski, Herb Windom, Tapan Audhya, Woody McGinnis
American Journal of Biochemistry and Biotechnology 4(2): 73-84, 2008
http://www.scipub.org/fulltext/ajbb/ajbb4273-84.pdf

It has been suggested that oxidative stress and/or mercury compounds play an important role in the pathophysiology of autism. This study compared for the first time the cerebellar levels of the oxidative stress marker 3-nitrotyrosine (3-NT), mercury (Hg) and the antioxidant selenium (Se) levels between control and autistic subjects. Tissue homogenates were prepared in the presence of protease inhibitors from the frozen cerebellar tissue of control (n=10; mean age, 15.5 years; mean PMI, 15.5 hours) and autistic (n=9; mean age 12.1 years; mean PMI, 19.3 hours) subjects. The concentration of cerebellar 3-NT, determined by ELISA, in controls ranged from 13.69 to 49.04 pmol gˉ1 of tissue; the concentration of 3-NT in autistic cases ranged from 3.91 to 333.03 pmol gˉ1 of tissue. Mean cerebellar 3-NT was elevated in autism by 68.9% and the increase was statistically significant (p=0.045). Cerebellar Hg, measured by atomic absorption spectrometry ranged from 0.9 to 35 pmol gˉ1 tissue in controls (n=10) and from 3.2 to 80.7 pmol gˉ1 tissue in autistic cases (n=9); the 68.2% increase in cerebellar Hg was not statistically significant. However, there was a positive correlation between cerebellar 3-NT and Hg levels (r=0.7961, p=0.0001). A small decrease in cerebellar Se levels in autism, measured by atomic absorption spectroscopy, was not statistically significant but was accompanied by a 42.9% reduction in the molar ratio of Se to Hg in the autistic cerebellum. While preliminary, the results of the present study add elevated oxidative stress markers in brain to the growing body of data reflecting greater oxidative stress in autism.

12. Metabolic biomarkers related to energy metabolism in Saudi autistic children
Al-Mosalem OA et al.
Clin Biochem. 2009 Jul;42(10-11):949-57. Epub 2009 Apr 17.
$ http://tinyurl.com/y9obtgc

OBJECTIVES: Energy metabolism is usually manipulated in many neurodegenerative diseases. Autism is considered a definable systemic disorder resulting in a number of diverse factors that may affect the brain development and functions both pre and post natal. The increased prevalence of autism will have enormous future public implications and has stimulated intense research into potential etiologic factors. This study aims to establish a connection between autism and the deterioration accompanied it, especially in the brain cognitive areas through a postulation of energy manipulation. MATERIALS AND METHODS: The biochemical changes in activities of enzymes and pathways that participate in the production of ATP as the most important high-energy compound needed by the human brain were measured in Saudi autistic children. Na(+)/K(+)ATPase, ectonucleotidases (NTPDases) (ADPase and ATPase) and creatine kinase (CK), were assessed in plasma of 30 Saudi autistic patients and compared to 30 age-matching control samples. In addition, adenosine mono, di and trinucleotides (ATP, ADP, and AMP) were measured calorimetrically in the red blood cells of both groups and the adenylate energy charge (AEC) was calculated. Moreover, lactate concentration in plasma of both groups was monitored. RESULTS: The obtained data recorded 148.77% and 72.35% higher activities of Na(+)/K(+)ATPase and CK respectively in autistic patients which prove the impairment of energy metabolism in these children compared to age and sex matching healthy controls. While ADPase was significantly higher in autistic patients, ATPase were non-significantly elevated compared to control. In spite of the significant increase of Na(+)/K(+)ATPase activity in autistic patients, there was no significant difference in the levels of ATP, ADP, and AMP in both groups and the calculated AEC values were 0.814+/-0.094 and 0.806+/-0.081 for autistic and control groups respectively. The unchanged AEC value in autistic patients was easily correlated with the induced activity of CK and ADPase as two enzymes playing a critical role in the stabilization of AEC. Lactate as an important energy metabolite for the brain was significantly higher in autistic patients compared to control showing about 40% increase. CONCLUSION: The present study confirmed the impairment of energy metabolism in Saudi autistic patients which could be correlated to the oxidative stress previously recorded in the same investigated samples. The identification of biochemical markers related to autism would be advantageous for earlier clinical diagnosis and intervention.

13. Autism: an emerging 'neuroimmune disorder' in search of therapy.
Theoharides TC, Kempuraj D, Redwood L.
Expert Opin Pharmacother. 2009 Sep;10(13):2127-43.

14. Cellular and mitochondrial glutathione redox imbalance in lymphoblastoid cells derived from children with autism.
James SJ, Rose S, Melnyk S, Jernigan S, Blossom S, Pavliv O, Gaylor DW.
FASEB J. 2009 Aug;23(8):2374-83

15. Efficacy of methylcobalamin and folinic acid treatment on glutathione redox status in children with autism.
James SJ, Melnyk S, Fuchs G, Reid T, Jernigan S, Pavliv O, Hubanks A, Gaylor DW.
Am J Clin Nutr. 2009 Jan;89(1):425-30

16. Biomarkers of environmental toxicity and susceptibility in autism.
Geier DA, Kern JK, Garver CR, Adams JB, Audhya T, Nataf R, Geier MR.
J Neurol Sci. 2009 May 15;280(1-2):101-8

17. A prospective study of transsulfuration biomarkers in autistic disorders.
Geier DA, Kern JK, Garver CR, Adams JB, Audhya T, Geier MR.
Neurochem Res. 2009 Feb;34(2):386-93.

18. Novel therapeutic targets for autism.
Theoharides TC, Doyle R, Francis K, Conti P, Kalogeromitros D.
Trends Pharmacol Sci. 2008 Aug;29(8):375-82.

19. Abnormal transmethylation/transsulfuration metabolism and DNA hypomethylation among parents of children with autism.
James SJ, Melnyk S, Jernigan S, Hubanks A, Rose S, Gaylor DW.
J Autism Dev Disord. 2008 Nov;38(10):1966-75.

20. Discerning the Mauve Factor, Part 1.
McGinnis WR, Audhya T, Walsh WJ, Jackson JA, McLaren-Howard J, Lewis A, Lauda PH, Bibus DM, Jurnak F, Lietha R, Hoffer A.
Altern Ther Health Med. 2008 Mar-Apr;14(2):40-50.

21. Discerning the Mauve factor, Part 2.

McGinnis WR, Audhya T, Walsh WJ, Jackson JA, McLaren-Howard J, Lewis A, Lauda PH, Bibus DM, Jurnak F, Lietha R, Hoffer A.
Altern Ther Health Med. 2008 May-Jun;14(3):56-62

22. Environmental risk factors for autism: do they help cause de novo genetic mutations that contribute to the disorder?
Kinney DK, Barch DH, Chayka B, Napoleon S, Munir KM.
Med Hypotheses. 2010 Jan;74(1):102-6.

Recent research has discovered that a number of genetic risk factors for autism are de novo mutations. Advanced parental age at the time of conception is associated with increased risk for both autism and de novo mutations. We investigated the hypothesis that other environmental factors associated with increased risk for autism might also be mutagenic and contribute to autism by causing de novo mutations. A survey of the research literature identified 9 environmental factors for which increased pre-conceptual exposure appears to be associated with increased risk for autism. Five of these factors--mercury, cadmium, nickel, trichloroethylene, and vinyl chloride--are established mutagens. Another four--including residence in regions that are urbanized, located at higher latitudes, or experience high levels of precipitation--are associated with decreased sun exposure and increased risk for vitamin D deficiency. Vitamin D plays important roles in repairing DNA damage and protecting against oxidative stress--a key cause of DNA damage. Factors associated with vitamin D deficiency will thus contribute to higher mutation rates and impaired repair of DNA. We note how de novo mutations may also help explain why the concordance rate for autism is so markedly higher in monozygotic than dizygotic twins. De novo mutations may also explain in part why the prevalence of autism is so remarkably high, given the evidence for a strong role of genetic factors and the low fertility of individuals with autism--and resultant selection pressure against autism susceptibility genes. These several lines of evidence provide support for the hypothesis, and warrant new research approaches--which we suggest--to address limitations in existing studies. The hypothesis has implications for understanding possible etiologic roles of de novo mutations in autism, and it suggests possible approaches to primary prevention of the disorder, such as addressing widespread vitamin D deficiency and exposure to known mutagens.

This document prepared by
Teresa Binstock
Researcher in Developmental & Behavioral Neuroanatomy
April 2010