CHARGING Towards an Understanding of Autism

There are many myths about medicine these days. Some are harmless, but many can lead to all sorts of problems. One very harmful medical myth is the idea that autism is caused by childhood vaccination. Although many careful studies have demonstrated that there is just no link between vaccines and autism, you can still find many websites that try to argue that vaccination causes autism. A while back, I participated in a debate hosted by one such website.

In the debate, I discussed and explained the studies that show there is simply no link between vaccines and autism. I also pointed out that some of the authors involved in these studies have a proven track record for finding a link between a vaccine and a serious medical condition, so it is hard to believe that they would miss a link between vaccines and autism if there is one. Not surprisingly, the website that hosted and heavily promoted the debate removed all mention of it afterwards, because the debate clearly showed the error of the idea they they are trying to promote.

Fortunately, real scientists are searching for the actual cause of autism, and lots of progress has been made. I recently ran across a study that addresses autism and the health of the mother during pregnancy. As a result of that study, I learned about a very interesting program that was started in 2003 and is just beginning to produce some very interesting results. It is called the Childhood Autism Risks from Genetics and the Environment (CHARGE) study. The study recognizes that there seem to be both genetic and environmental risk factors for autism, and it is designed to produce rigorous research that will help us understand both.

The CHARGE study has already produced at least three very important and somewhat surprising results.

The first important study compared 304 autistic children to 259 control children that seemed to be developing normally. The researchers had a detailed history of where the mothers lived during pregnancy. What they found was that when mothers lived within one-quarter mile of a freeway at the time of delivery, the child was about 86% more likely to be autistic. More importantly, if the mother lived within one-quarter mile of a freeway throughout the third trimester of her pregnancy, the child was more than twice as likely to be autistic. Interestingly enough, this relationship disappeared if the mother was more than one-quarter mile away from a freeway, and it exists only for freeways, not other kinds of major roads.1

The second important study dealt with prenatal vitamins. When parents plan to have a child, a doctor will often recommend that the mother start taking prenatal vitamins before she becomes pregnant. That way, her body is prepared for the baby that she hopes will be conceived. The study looked at 288 children who had autism, an additional 141 diagnosed with autism spectrum disorder (ASD), and 278 control children who seemed to be developing normally. It found that if a mother started taking prenatal vitamins before she got pregnant, she was 62% less likely to have an autistic child. In addition, they looked at specific genetic anomalies related to metabolism. They found that when the mother had specific genetic anomalies and did not take prenatal vitamins before pregnancy, she was up to 4.5 times more likely to have an autistic child. If the child had one specific genetic anomaly and the mother did not take prenatal vitamins before pregnancy, the child was more than 7 times more likely to have autism or ASD.2

The most recent study (the one that made me aware of the CHARGE data to begin with) looked at the relationship between three metabolic conditions (diabetes, hypertension, and obesity) in the mother and the child’s chance of having autism. It examined 517 children with autism or ASD, 172 children that were otherwise developmentally disabled, and 315 control children that seemed to be developing normally. It found that if the mother was obese, she was 67% more likely to have a child with autism or ASD and nearly twice as likely to have a child with any developmental disorder. Mothers with diabetes were also 67% more likely to have a child with autism or ASD. Hypertension seemed to have an effect as well, but it wasn’t strong enough to be measured with the number of children studied.3

So what does all this all mean? Well, first it’s important to note that none of these studies show that living near a highway, lack of prenatal vitamins, or metabolic conditions cause autism or ASD. They simply show that autism and ASD are correlated with these conditions. Nevertheless, these correlations do raise some interesting possibilities. The first study I discussed references other studies that show that freeway-related pollution tends to dissipate to background levels more than one-quarter of a mile away from the freeway. That means their results indicate that exposure to air pollution during pregnancy (especially in the third trimester) might be one cause of autism.

The second and third studies raise the possibility that autism is related to metabolism. A lack of prenatal vitamins before pregnancy made all mothers more likely to have autistic children, but the chance rose even more when the mother had a metabolic genetic anomaly. Also, the fact that diabetes and obesity in the mother are correlated with autism or ASD adds further weight to the metabolic link. However, it’s clearly not all about the mother. Remember, the most significant chance of having an autistic child came when the child had a metabolic genetic anomaly and the mother didn’t take prenatal vitamins before she conceived.

The bottom line is that both genetics and environment play a role in autism. In addition, researchers should start focusing on metabolic conditions (both genetic and otherwise), as they seem to be important.


1. Volk HE, Hertz-Picciotto I, Delwiche L, Lurmann F, and McConnell R., “Residential proximity to freeways and autism in the CHARGE study,” Environmental Health Perspectives 119(6):873-877, 2010
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2. Schmidt RJ, Hansen RL, Hartiala J, Allayee H, Schmidt LC, Tancredi DJ, Tassone F, and Hertz-Picciotto I., “Prenatal vitamins, one-carbon metabolism gene variants, and risk for autism,” Epidemiology 22(4):476-85, 2011
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3. Krakowiak P, Walker CK, Bremer AA, Baker AS, Ozonoff S, Hansen RL, and Hertz-Picciotto I., “Maternal metabolic conditions and risk for autism and other neurodevelopmental disorders,” Pediatrics 129(5):e1121-8, 2012
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16 thoughts on “CHARGING Towards an Understanding of Autism”

  1. Very interesting . . . It seems that the freeway proximity correlation could also explain the very low autism rates in the Amish community, which is often explained by lack of vaccination. The genetic connection would also make sense with a low occurrence in the Amish as well, since they have a relatively limited gene pool.

  2. I find this article very interesting, considering I plan to be a midwife, but I do have some questions about vaccines. First of all, which vaccines do you consider strictly necessary? I am well aware that many vaccines (tetanus, meningitis, polio, rabies, smallpox)save many lives, but why are there so many others? My mother kept allowing fewer and fewer shots for her five children, and the youngest ones are the healthiest. Whenever we do get shots, we get up to a month of listlessness and random fevers. It doesn’t seem worth it. My youngest sister is probably the healthiest child I know, and she has had so few shots that her pediatrician compared her to a newborn. What diseases *are* linked to vaccines? I intend to get my newborns only the completely necessary ones, and we’ll see from there. Knowing how much you advocated vaccines, I would still appreciate it if you did detail any qualms you have on the subject.

    1. Those are great questions, Grace. First, the list of necessary vaccines changes from person to person. It’s all about managing risks. If a family member (or the entire family) travels a lot, the list of necessary vaccinations increases. If a family has a history of allergy to eggs, the list of necessary vaccinations decreases. In determining what vaccinations to get, people should work with a health-care provider who is knowledgeable about vaccines as well as the family’s medical history. My daughter had all the vaccinations on the standard schedule, because we worked with her doctor and decided she was better off with all of them. I have had substantially more than those on the standard schedule, however, because I travel so widely.

      There are so many vaccines because there are so many diseases. While some diseases have the reputation of being rather harmless, the medical community knows otherwise. For example, chicken pox is considered a “mild” childhood disease. However, before the vaccine was used, chicken pox resulted in 8,000–18,000 hospitalizations each year, and 100–150 of those people died due to complications arising from the chicken pox. [Lopez, Adriana; Schmid, Scott; Bialek, Stephanie, “Chapter 17: Varicella,” in Manual for the Surveillance of Vaccine-Preventable Diseases (5th ed.), 2011] Since the introduction of the vaccine, those numbers have dropped by 80% [Seward JF, Watson BM, Peterson CL, et al., “Varicella disease after introduction of varicella vaccine in the United States, 1995–2000,” Journal of the American Medical association 287(5):606-611, 2002]

      When you ask, “What diseases *are* linked to vaccines?” are you asking about side effects? The CDC keeps a good list of the possible side effects of all vaccines. This is one reason the necessary vaccines change from person to person. Some people are more susceptible to some side effects, and that means the risk outweighs the benefit of the vaccine for those people. This is the same for almost any medication (or food, for that matter). Some people cannot take aspirin due to potential side effects, even though aspirin is very safe for most people. Some people cannot eat peanuts because of potential side effects, even though peanuts are very safe for most people.

  3. Thanks for this report, Dr. Wile. I wonder if sometime in the future you could address the issue of the use of aborted fetal cells in developing vaccines? I’ve just recently learned of this practice, and frankly, it’s disturbing. Where can one go to get unbiased, reliable information on such a sensitive subject?

    1. Thanks for the question, Heather. I have actually already discussed that issue. As the article I linked explains, the vaccines that are grown on fetal cells use self-perpetuating lines from abortions that took place more than 40 years ago. New abortions are not used to produce these vaccines. Thus, the use of the vaccines does not, in any way, affect the number of abortions done. This is why even the Vatican encourages people to use the vaccines while at the same time pushing for alternatives. Also, please note if you think using such vaccines is not morally correct, there are only four that you need avoid: rubella (the “R” in “MMR”), rabies, chicken pox, and hepatitis A. They are the only ones on the standard schedule that are grown in fetal cells. There are also some alternative versions of the vaccines that might be hard to find but are worth asking about.

  4. I appreciate your question and request gracekalman. I am also interested in further details. My Mom has always bee leery of vaccinations, in fact, I have never had shots. I was home schooled, so I wasn’t really around a lot of people every single day, however, my Dad is a school teacher in a public school, so I imagine he would bring home germs and virus’s from school that I would have been exposed to. I have also heard (sorry I don’t have any examples) that some vaccinations just don’t work, you get the illness again years later.

    What are some of the reason for the so called conspiracy-theories behind vaccines? There must be some reason there are so many anti-vaccine people out there.

    1. Amuzani, the idea that some vaccinations just don’t work isn’t true. In order for a vaccine to be approved for use, it has to pass a series of clinical tests that demonstrate it is effective against the disease and the risk of any possible side effects is very low compared to the risk of the disease itself. This is why vaccines can be demonstrated to be very effective.

      There are probably several reasons for the anti-vaccination movement. Mathematics demonstrates, for example, that there will be 46.8 Sudden Infant Death Syndrome deaths within 24 hours of a pertussis vaccination by sheer coincidence. Parents of these unfortunate children will see that the children got a pertussis vaccine and then died within 24 hours. It is natural for them to blame the vaccine and thus become anti-vaccination, even though we know that the pertussis vaccine actually reduces a child’s risk of Sudden Infant Death Syndrome! So in the end, grief-stricken parents end up putting blame on something that isn’t at fault. This happens with many medical conditions. Indeed, people still think that vaccines cause autism (despite the studies that clearly say they don’t) specifically because they notice the autism symptoms a short time after the child gets vaccinated. There are also some who make money by keeping people from getting vaccines, as they sell “alternative” ways to keep your children healthy. There are others who are very emotional about vaccines, because of the fetal tissue issue that Heather brought up. This makes them “hate” vaccines, and as a result, they want to fight against vaccines.

      There are many movements in the U.S. that have no basis in fact but are nevertheless somewhat popular, such as the “we never went to the moon” movement. There are a variety of reasons why people buy into them, but as is the case with evolution, the fact that people believe in something doesn’t make it correct.

  5. As you pointed out, correlation does not imply causation.

    A common denominator in all the studies you mentioned could be low socio-economic status. Low socio-economic status is correlated with a host of medical problems. So, autism may or may not have anything whatsoever to do with metabolic problems. They could both be the result of stress from poor living conditions, for example. So hard to prove causation in free-living human beings.

    1. Common Sense, I agree that it is hard to demonstrate causation, but it is not impossible. For example, consider the study about vitamins. Sure…low income could correlate with not taking vitamins, but the study went farther than that. It showed the effect of not taking vitamins was significantly increased by specific gene variants. It’s hard to see how gene variants could be correlated with low income or something like that. Thus, I do think there is strong evidence to suggest some kind of metabolic link. Once again, causation hasn’t been demonstrated, but these studies could lead to other studies that do demonstrate causation.

  6. If obesity, diabetes, and possibly hypertension lead to a higher chance of having a child with Autism, perhaps that might explain the increase in number of cases, as apparently the numbers of people who have diabetes or hypertension, or are obese is higher than in the past. Did the article mention that? (I would just go and read the article myself, but am rather pressed for time right now.)

    1. Vivielle, the third study I discussed does, indeed, bring this up. We know that at least one reason autism rates are on the rise is that parents are getting older, and the older the parents, the more likely the child is to be autistic. The authors of the study mention this fact and then go on to say that metabolic conditions are also on the rise, and the apparent link between metabolic conditions and autism might be another part of the explanation for why autism is on the rise.

  7. Dr Wile, how about the problem of a mom who did NOT live within 1/4 mile of a freeway, took prenatals, definitely not obese, nor type-2 diabetes, nor hypertension, yet has a child diagnosed with an ASD? My brother and sister-in-law fit this category. Their oldest has been diagnosed with Aspergers. There are 5 factors you listed in the article, yet my brother and sister in law do NOT fit a single one. (They were also still in their 20’s when they had their children.) The only one thing I can think of is undiagnosed Celiac in my sister-in-law. (Once they removed gluten from their diet, the oldest improved dramatically, but still has problems.) It’s like I read that you’re more likely to be diagnosed with Type 1 diabetes if someone else in your family has it, but most people who are diagnosed have no one in their family with Type 1 diabetes. I can’t wrap my head around that.

    1. Trish, there is a lot about medicine that we don’t know. One thing we do know, however, is that many maladies don’t have straightforward causes. There are things that increase your risk for certain maladies, but they are not necessarily direct causes. For example, smoking strongly increases your risk for lung cancer. However, even people who have never smoked, never been exposed to second-hand smoke, and never been exposed to air pollution can still get lung cancer. They are significantly less likely to get it, but sometimes they get it. So even if these metabolic conditions are true risk factors for autism, that doesn’t mean only people with such conditions will have children with autism. Just as some non-smokers will get lung cancer, some very healthy parents who live in pristine conditions will still have autistic children.

      In regards to Type 1 diabetes, there are many different risk factors. Family history is one, but geography is another (type 1 diabetes increases as you travel away from the equator). In addition, diet seems to play a role (although much smaller than for type 2 diabetes), viral exposure seems to play a role, and low Vitamin D seems to play a role (perhaps that is the reason it increases as you travel away from the equator). It is well known that geography is the most important: people in the U.S. are 400 times more likely to have type 1 diabetes than those in Venezuela. Most likely, some of the other risk factors are more important than family history as well. Thus, while having someone in your family with type 1 diabetes does increase your risk, other factors are more important, which is why more people who are diagnosed with type 1 diabetes have no family history of it.

  8. I just wanted to thank you for taking the time to respond to my question and linking to your earlier article! Thanks so much!

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