Introduction: The following article was written by an epidemiologist/biostatistician, who has been studying the autism epidemic for many years. The intention was to present this information in a manner which would be understandable to all readers, including individuals without a science background. If something is unclear, please feel free to contact the author at the email address provided at the bottom of this website.
Background - The Autism Epidemic
The most recent CDC data shows that autism now affects one in 110 children overall and one in 70 boys. Some continue to deny we are experiencing an epidemic, but it is becoming increasingly obvious that we are. Furthermore, scientific research indicates the increase in prevalence is not simply a matter of more children being diagnosed now than in the past, but due to a real increase in affected children.[2,3] The pressing question for us as a society is why is this happening to our children? Why are there more autistic children now than in the past? After extensive research, I have come to the conclusion that the autism epidemic is due to an environmentally triggered encephalopathy/neuropathy of the prenatal period, infancy, or early childhood. In plain language, it appears the autism epidemic is the result of an interactive effect of multiple neurotoxins; the specific neurotoxins suspected are: acetaminophen, free glutamate, and aspartame. While this may be difficult to initially believe, because we have been led to believe the above are safe, the sections to follow will provide evidence for the role of acetaminophen, free glutamate and aspartame, in the autism epidemic.
The first neurotoxin to be discussed is acetaminophen. Acetaminophen’s neurotoxicity is attributed to the fact that a fraction of acetaminophen is broken down into n-acetyl-p-benzoquinone imine (NAPQI). Recent research shows that NAPQI kills cortical neurons. Pediatric exposure to acetaminophen increased suddenly during the 1980’s, when acetaminophen replaced aspirin as the recommended pain killer for use in the pediatric population, after the Centers for Disease Control issued a warning that aspirin may be associated with Reye’s Syndrome (an association which has never been conclusively demonstrated ). This greatly increased the number of infants and toddlers exposed to acetaminophen’s neurotoxic by-product, NAPQI. Unfortunately, acetaminophen has become the most frequently used analgesic by pregnant women as well. [13,14] To place acetaminophen on the autism timeline, rates of autism began to rise during the 1980’s, which coincides with the time that acetaminophen exposure, and therefore exposure to neurotoxic NAPQI, suddenly increased. [5,6]
The next toxin to be discussed is free glutamate. Free glutamate is promoted by the glutamate industry as safe; however, it is a neurotoxin, more specifically it is an excitotoxin.  Free glutamate is an additive present in multiple childhood vaccines.  Although thimerosal has been widely implicated as a potential causative factor in the autism epidemic, I suspect the vaccine component which is relevant to the autism epidemic is actually free glutamate and not thimerosal. Animal research supports this assertion. In 1969, Dr. Olney showed that injecting baby mice with free glutamate caused neurological harm (brain lesions) in these animals.  Disturbingly, decades after this research, the current CDC vaccine schedule has us injecting our infants and toddlers with vaccines containing free glutamate multiple times over the course of their young lives, despite the demonstrated neurological harm of injecting laboratory animals with free glutamate. For many years now, countless parents have been reporting their previously normally developing children regressed into autism following vaccinations, and sadly these parents have been mostly dismissed by the medical profession and by the media as hysterical.
What is Free Glutamate and Where Else is it Found?
Free glutamate is probably most widely known as the adverse reaction causing portion of the food additive monosodium glutamate (MSG). However, it should be noted that strict avoidance of monosodium glutamate is no longer sufficient to avoid dietary exposure to neurotoxic processed free glutamate. It seems that in response to public concern regarding the danger of monosodium glutamate, food manufactures have found ways to hide processed free glutamate in food in ways which do not require them to list monosodium glutamate (MSG) among the ingredients on the label. Currently, neurotoxic free glutamate is hidden in our food under several harmless sounding names, such as: yeast extract, hydrolyzed vegetable protein, and soy protein to name only a few. It is abundant in our food supply and sadly this neurotoxin is routinely consumed with every meal. Please see the Truth is Labeling website for a list of ingredients and food items which contain processed free glutamate (please note that free glutamate is sometimes also referred to as free glutamic acid). The reason food manufacturers currently add processed free glutamate to practically everything is because it tastes great and it is relatively cheap; it produces a rich savory flavor, which has actually been described as the 5th flavor of umami. Dr. Russell Blaylock, neurosurgeon and author, describes processed free glutamate as “the taste that kills”. This is because free glutamate is not merely a flavoring; it is a neurotoxin.
To understand how free glutamate harms the nervous system, it first needs to be understood that free glutamate (glutamic acid) actually functions as a neurotransmitter and is essential for proper neurological function, in small quantities. However, in large quantities, it acts as an excitotoxin causing the neurons to fire rapidly and repeatedly which can literally excite them to death . As the manufacturers of processed foods like to point out, glutamate is also present in healthy, unprocessed foods. However, in these natural, unprocessed foods, glutamate is not typically harmful, because most of the glutamate in such foods is in its bound form which is freed slowly and in appropriate amounts. In contrast, in its unnatural, processed form, such as from MSG, yeast extract, or hydrolyzed vegetable protein the glutamate is already free and the neurons are exposed to excessive amounts very quickly. When this occurs, the free glutamate acts as an excitotoxin, causing neurons to fire rapidly and repeatedly which can damage the neurons or even excite them to death .
As previously mentioned, rates of autism began to increase in the 1980’s [5,6]. It seems that changes in eating habits since the 1980’s, notably the reduction in home cooked meals, with the corresponding increase in the consumption of prepackaged, microwaveable convenience foods and restaurant food/take-out food has increased the amount of neurotoxic processed free glutamate consumed in the typical diet on a daily basis.
The final neurotoxin to be discussed is aspartame. Aspartame breaks down into aspartic acid which is an excitotoxin with neurotoxic effects very similar to those of free glutamate and like free glutamate it can similarly excite neurons to death . Initially, aspartame was found mainly in diet soft drinks marketed toward adults (particularly women, which includes pregnant women). Aspartame’s use has since spread to products marketed directly toward very young children such as pudding cups, flavored yogurt and various deserts and candies. Furthermore, aspartame is also added as a sweetener to many pediatric pharmaceutical products, such as children’s vitamins, the liquid suspension form of the antibiotic Augmentin, and children’s Tylenol. For a more complete list of children’s pharmaceutical products which contain aspartame please refer to this website.
To place aspartame on the autism timeline, rates of autism began rising in the 1980’s. [5,6] Aspartame was approved for use in the United States in 1983.
Neurotoxin Interactive Effects
With respect to the development of autism spectrum disorders, it seems there is an interactive effect between NAPQI (the toxic by-product of acetaminophen) and free glutamate and/or aspartic acid. Typically, neurotoxic NAPQI is quickly detoxified in the body by glutathione; however, this process leads to depletion of glutathione. This is significant because glutathione is the major free radical scavenger in the brain. [10,11] A detailed explanation of “free radical scavenger” is beyond the scope of this article, but in plain language, when neurotoxins such as free glutamate or aspartic acid (aspartame) wreak havoc on your child’s nervous system, these toxins cause a cascade of destructive events, and it is glutathione’s role to attempt to keep the resulting damage in check. This potential interactive effect between acetaminophen and free glutamate is supported by recent research. Researchers from the University of California, San Diego, found that among children who experienced an adverse reaction to the MMR vaccine (a vaccine which contains free glutamate), the children whose adverse vaccine reactions were treated with acetaminophen (Tylenol) were eight times more likely to develop an autism spectrum disorder than the children who were treated with ibuprofen (Advil). 
For detailed information regarding MMR and other vaccine ingredients, please refer to the official Centers for Disease Control website. Pay particular attention to the following vaccine ingredients: monosodium glutamate, yeast extract and gelatin. These are known sources of neurotoxic processed free glutamate. Additional ingredients listed as vaccine components which may also be sources of neurotoxic processed free glutamate include: amino acids, egg protein, mouse serum protein, yeast protein, bovine protein, and Medium 199. Please note that the MMR vaccine, a vaccine routinely implicated in the autism epidemic and the varicella vaccine (which is often administered along with the MMR) both contain relatively large amounts of processed free glutamate.
In summary, while many will attempt to pinpoint a genetic cause for autism, this seems misguided from an epidemiological point of view when trying to unravel the autism epidemic. Genes do not change significantly over the course of a few decades. The drastic and sudden increase in autism rates clearly is due to environmental causes, and the current evidence appears to point to acetaminophen, free glutamate and aspartame as the likely environmental triggers. However, additional research in this area is needed, and in terms of genetics, it is plausible that some individuals, due to genetic variation, are more vulnerable to environmental neurotoxins such as acetaminophen, free glutamate, and aspartame than others, placing them at greater risk.
- MMWR Surveillance Summary "Prevalence of Autism Spectrum Disorders---Autism and Developmental Disabilities Monitoring Network, United States, 2006
- Newschaffer CJ, Falb MD, Gurney JG. National autism prevalence trends from United States special education data. Pediatrics. 2005 Mar;115(3):e277-82.
- Yeargin-Allsopp M, Rice C, Karapurkar T, Doernberg N, Boyle C, Murphy C. Prevalence of autism in a US metropolitan area. JAMA. 2003 Jan 1;289(1):49-55.
- Posadas I, Santos P, Blanco A, Munoz-Fernandez M, Cena V. Acetaminophen induces apoptosis in rat cortical neurons. PLoS ONE. 2010 5(12).
- Previc FH. Prenatal influences on brain dopamine and their relevance to the rising incidence of autism. Med Hypotheses. 2007:68(1):46-60.
- Good P. Did acetaminophen provoke the autism epidemic? Altern Med Rev. 2009 Dec;14(4):364-72.
- Orlowski JP, Hanhan UA, Fiallos MR. Is aspirin a cause of Reye’s syndrome? A case against. Drug Saf. 2002;25(4):225-31.
- Blaylock RL. Excitotoxins the taste that kills. Albuquerque,NM: Health Press; 1997.
- Olney JW. Brain lesions, obesity, and other disturbances in mice treated with monosodium glutamate. Science. 1969 May:164(880):719-21.
- Gawryluk JW, Wang JF, Andreazza AC, Shao L, Young LT. Decreased levels of glutathione, the major brain antioxidant, in post-mortem prefrontal cortex from patients with psychiatric disorders. Int J Neuropsychopharmacol. 2011 Feb;14(1):123-30. Epub 2010 Jul 16.
- Chiba M, Pang KS. Glutathione depletion kinetics with acetaminophen. A simulation study. Drug Metab Dispos. 1995 Jun;23(6):622-30.
- Schultz ST, Klonoff-Cohen HS, Wingard DL, Akshoomoff NA, Macera CA, Ji, M. Acetaminophen (paracetamol) use, measles-mumps-rubella vaccination, and autistic disorder: the results of a parent survey. Autism. 2008 May;12(3). 293-307.
- Werler MM, Mitchell AA, Hernandez-Dias S, Honein MA. Use of over-the counter medications during pregnancy. Am J Obstet Gyecol 2005; 193: 771-77.
- Rathmell JP, Viscomi CM, Asburn MA. Management of nonobstetric pain during pregnancy and lactation. Anesth Analg. 1997 Nov; 85(5): 1074-87.
- Department of Health and Human Services, Centers for Disease Control and Prevention. “Ingredients in Vaccines - Fact Sheet”.
P. Vincent, MPH
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