Richard E Frye & John Slattery
Arkansas Children’s Research Institute, Little Rock AR
Rossignol Medical Center, Irvine CA
A recent study demonstrated that a blood test might be able to differentiate children with autism spectrum disorder (ASD) from typically developing children.1 The study examined one carbon metabolism and its related pathways. These pathways are of the upmost importance in ASD and are essential for many critical processes in the cells of the body, including methylation which regulates turning genes on and off, producing the precursors to genetic material and producing the major antioxidant in the body known as glutathione.2
This news is not really new, however the dataset’s potential predictive ability is intriguing. Over a decade ago, Dr. Jill James, demonstrated that children with ASD have abnormal one carbon metabolism and suggested that these metabolic markers define an endophenotype (subgroup) of children with ASD.3 Furthermore, Dr. James demonstrated that several common variations in genes which provide the instructions for cellular proteins and enzymes result in an increase in the risk of developing ASD with these variations interacting in complex ways.3 This suggests several “kinks” in these metabolic pathways may add up to predispose a child to develop ASD.
The metabolic markers found in this recent study are linked to oxidative stress – a finding that has been verified again and again. Oxidative stress is a process in which toxic molecules damage parts of the cell. Studies have demonstrated that key parts of the cell, which include: proteins such as those important for making the machinery of the cells’ enzymes, fats that are essential for making the membranes that define the cellular structure, and genetic material that encodes the cellular instructions, are all damaged by oxidative stress in children with ASD.2 Markers of oxidative damage have been found in many parts of the body in children with ASD, including immune cells4 and brain tissue.5 In addition, this oxidative stress has been associated with inflammation in children with ASD.6 In addition, we have recently demonstrated that oxidative stress can negatively affect mitochondrial function in children with ASD.7-9 Therefore, oxidative stress represents a potential cause of both the abnormal biochemistry and behavioral features reported in some individuals with autism.
One of the wonderful possibilities of identifying metabolic abnormalities is that they are potentially treatable. Based on observations from clinicians, Dr. Jill James demonstrated that a simple and safe treatment of three times a week injected Methyl-B12 and daily oral folinic acid could improve these abnormalities in metabolism.10 Later our research group at Arkansas Children’s Research Institute (ACRI) further demonstrated that this improvement was related to substantial improvements in development and behaviors.11 Dr. Robert Hendren at the University of California – San Francisco (UCSF) has further verified this finding in a double-blind placebo-controlled study using Methyl-B12 in individuals with autism.12
Our research team at ACRI recently demonstrated the importance of folate, the key nutrient of one-carbon metabolism, in the treatment of ASD in several studies. Several years ago Dr. Dan Rossignol and myself demonstrated that many children with ASD, possibly up to 75%, have a block in their ability to transport folate into the brain because of an autoantibody to the folate receptor alpha.13 Other studies have suggested that children with this blockage may have particular clinical characteristics14 and that these autoantibodies may affect the development of the thyroid.15 Recently our research team demonstrated that children with this block in folate transport may respond to a special type of reduced folate known as folinic acid (also known as leucovorin calcium) without measurable adverse effects.16 Our group at ACRI also recently showed that folate supplementation positively influences mitochondrial function.17
Interestingly, some of the same abnormalities and treatments that are related to ASD are also found during the prenatal period. For example, Dr. James demonstrated that one of the same variations in genes found in children with ASD also predispose children to develop ASD if they are found in the child’s mother.18 It is also intriguing and of note that the folate receptor alpha autoantibody is linked to birth defects when found in the mother and a recently developed animal model demonstrates that these autoantibodies in mother rodents result in ASD like behaviors in the offspring,19 with folate supplementation and an immune modulating therapy reversing this effect.20 Additionally, several studies have demonstrated that folate supplementation during pregnancy decreases the risk of developing autism.21,22
Another study presented at the International Meeting for Autism Research by Dr M. Daniele Fallin, PhD, of the Johns Hopkins Bloomberg School of Public Health has gained a lot of press. This study claims that an increased blood level of folate in the mother is related to their children developing ASD. This has been interpreted as folate causing ASD. However, this is where it is important to understand the difference between oxidized and reduced folate. Folic acid, the type of folate that is used to fortify our food and included in most prenatal vitamins, is an oxidized form of folate. In order for the body to use this type of folate it needs to be metabolized into a reduced form (beneficial form) of folate. Many of the abnormalities identified in children with ASD and their mother are blocks in folate metabolism that prevent oxidized folate, like folic acid, from being metabolized and transported into cells. Thus, it would be expected that children with ASD and their mothers to have higher levels of folic acid in their blood since it is not being metabolized and cannot easily enter cells. Thus, an increased level of folic acid in the blood is probably a marker of abnormal folate metabolism not a cause of it. Because this study by Dr. Fallin and his associates has not undergone peer review and has not been published, it is unclear if they took these findings into account.
This currently published study pushes forward medical science and demonstrates the potential for a better understanding of the biological underpinnings of ASD and how a careful statistical analysis may pave the way for the future using multivariate approaches to understanding a multifactorial disease process. While the initial results are exciting and compelling, the study needs to be verified in much larger samples of children with ASD before generalizations can be made. The Howsmon et al paper1 pushes forward the field associated with metabolic abnormalities in ASD that has been ongoing for a few decades and provides promise that we are making headway in understanding the pathophysiology associated with ASD. This may aid in the development of new treatment options for children with these metabolic blocks. The tantalizing fact that many of these same abnormalities may be found prenatally suggests that we may be able to identify those at risk for developing ASD before birth and provide treatment strategies to stop and maybe even reverse any biological abnormalities that can result in ASD as early as possible. This also could lead to preventative strategies, giving us much hope for the future.
1 Howsmon, D. P., Kruger, U., Melnyk, S., James, S. J. & Hahn, J. Classification and adaptive behavior prediction of children with autism spectrum disorder based upon multivariate data analysis of markers of oxidative stress and DNA methylation. PLoS Comput Biol 13, e1005385, doi:10.1371/journal.pcbi.1005385 (2017).
2 Frye, R. E. & James, S. J. Metabolic pathology of autism in relation to redox metabolism. Biomark Med 8, 321-330, doi:10.2217/bmm.13.158 (2014).
3 James, S. J. et al. Metabolic endophenotype and related genotypes are associated with oxidative stress in children with autism. Am J Med Genet B Neuropsychiatr Genet 141B, 947-956, doi:10.1002/ajmg.b.30366 (2006).
4 Rose, S. et al. Intracellular and extracellular redox status and free radical generation in primary immune cells from children with autism. Autism Res Treat 2012, 986519, doi:10.1155/2012/986519 (2012).
5 Rose, S. et al. Evidence of oxidative damage and inflammation associated with low glutathione redox status in the autism brain. Transl Psychiatry 2, e134, doi:10.1038/tp.2012.61 (2012).
6 Rossignol, D. A. & Frye, R. E. Evidence linking oxidative stress, mitochondrial dysfunction, and inflammation in the brain of individuals with autism. Front Physiol 5, 150, doi:10.3389/fphys.2014.00150 (2014).
7 Rose, S. et al. Mitochondrial and redox abnormalities in autism lymphoblastoid cells: a sibling control study. FASEB J 31, 904-909, doi:10.1096/fj.201601004R (2017).
8 Rose, S. et al. Oxidative stress induces mitochondrial dysfunction in a subset of autism lymphoblastoid cell lines in a well-matched case control cohort. PLoS One 9, e85436, doi:10.1371/journal.pone.0085436 (2014).
9 Rose, S. et al. Oxidative stress induces mitochondrial dysfunction in a subset of autistic lymphoblastoid cell lines. Transl Psychiatry 4, e377, doi:10.1038/tp.2014.15 (2014).
10 James, S. J. et al. Efficacy of methylcobalamin and folinic acid treatment on glutathione redox status in children with autism. Am J Clin Nutr 89, 425-430, doi:10.3945/ajcn.2008.26615 (2009).
11 Frye, R. E. et al. Effectiveness of methylcobalamin and folinic Acid treatment on adaptive behavior in children with autistic disorder is related to glutathione redox status. Autism Res Treat 2013, 609705, doi:10.1155/2013/609705 (2013).
12 Hendren, R. L. et al. Randomized, Placebo-Controlled Trial of Methyl B12 for Children with Autism. J Child Adolesc Psychopharmacol 26, 774-783, doi:10.1089/cap.2015.0159 (2016).
13 Frye, R. E., Sequeira, J. M., Quadros, E. V., James, S. J. & Rossignol, D. A. Cerebral folate receptor autoantibodies in autism spectrum disorder. Mol Psychiatry 18, 369-381, doi:10.1038/mp.2011.175 (2013).
14 Frye, R. E. et al. Blocking and Binding Folate Receptor Alpha Autoantibodies Identify Novel Autism Spectrum Disorder Subgroups. Front Neurosci 10, 80, doi:10.3389/fnins.2016.00080 (2016).
15 Frye, R. E. et al. Thyroid dysfunction in children with autism spectrum disorder is associated with folate receptor alpha autoimmune disorder. J Neuroendocrinol, doi:10.1111/jne.12461 (2017).
16 Frye, R. E. et al. Folinic acid improves verbal communication in children with autism and language impairment: a randomized double-blind placebo-controlled trial. Mol Psychiatry, doi:10.1038/mp.2016.168 (2016).
17 Delhey, L. M. et al. The Effect of Mitochondrial Supplements on Mitochondrial Activity in Children with Autism Spectrum Disorder. J Clin Med 6, doi:10.3390/jcm6020018 (2017).
18 James, S. J. et al. A functional polymorphism in the reduced folate carrier gene and DNA hypomethylation in mothers of children with autism. Am J Med Genet B Neuropsychiatr Genet 153B, 1209-1220, doi:10.1002/ajmg.b.31094 (2010).
19 Sequeira, J. M. et al. Exposure to Folate Receptor Alpha Antibodies during Gestation and Weaning Leads to Severe Behavioral Deficits in Rats: A Pilot Study. PLoS One 11, e0152249, doi:10.1371/journal.pone.0152249 (2016).
20 Desai, A., Sequeira, J. M. & Quadros, E. V. Prevention of behavioral deficits in rats exposed to folate receptor antibodies: implication in autism. Mol Psychiatry, doi:10.1038/mp.2016.153 (2016).
21 Suren, P. et al. Association between maternal use of folic acid supplements and risk of autism spectrum disorders in children. Jama 309, 570-577, doi:10.1001/jama.2012.155925 (2013).
22 Schmidt, R. J. et al. Maternal periconceptional folic acid intake and risk of autism spectrum disorders and developmental delay in the CHARGE (CHildhood Autism Risks from Genetics and Environment) case-control study. Am J Clin Nutr 96, 80-89, doi:10.3945/ajcn.110.004416 (2012).