Public release date: 5-Feb-2004
Contact: Aimee Midei
[email protected]
310-206-6739
Molecular Psychiatry
A link between thimerosal and the brain: Can vaccines affect central nervous system function?
According to new research from Northeastern University pharmacy professor Richard Deth and colleagues from the University of Nebraska, Tufts, and Johns Hopkins University, there is an apparent link between exposure to certain neurodevelopmental toxins and an increased possibility of developing neurological disorders including autism and attention-deficit hyperactivity disorder. The research – the first to offer an explanation for possible causes of two increasingly common childhood neurological disorders – will be published in the April 2004 issue of the journal Molecular Psychiatry, and earlier as advance online publication.
Though some speculation exists regarding this link, Deth and his colleagues found that exposure to toxins, such as ethanol and heavy metals (including lead, aluminum and the ethylmercury-containing preservative thimerosal) potently interrupt growth factor signaling, causing adverse effects on methylation reactions (i.e. the transfer of carbon atoms). Methylation, in turn, plays a significant role in regulating normal DNA function and gene expression, and is critical to proper neurological development in infants and children. Scientists and practitioners have identified an increase in diagnoses of autism and ADHD in particular, though the reasons why are largely unknown.
In their work, the scientists found that insulin-like growth factor-1 (IGF-1) and the neurotransmitter dopamine both stimulated folate-dependent methylation pathways in neuronal cells. At the same time they noted that compounds like thimerosal, ethanol and metals (like lead and mercury) effectively inhibited these same biochemical pathways at concentrations that are typically found following vaccination or other sources of exposure. By better understanding what happens when infants and children are exposed to these materials, the work of Deth and his colleagues helps to explain how environmental contact with metals and administration of certain vaccines may lead to serious disorders that manifest themselves during childhood, including autism and ADHD.
“Scientists certainly acknowledge that exposure to neurotoxins like ethanol and heavy metals can cause developmental disorders, but until now, the precise mechanisms underlying their toxicity have not been known.” said Deth. “The recent increase in the incidence of autism led us to speculate that environmental exposures, including vaccine additives might contribute to the triggering of this disorder.”
Thimerosal, which was largely phased out in the U.S. and in Europe starting in 2000,was often used for its preservative abilities in multi-dose units of vaccines for diseases like hepatitis, whooping cough, tetanus and diptheria. Today, most vaccines carry only trace amounts of it, according to the CDC. But in larger, multi-dose vials of these vaccines, often shipped to and used in third world countries, thimerosal is still very common. Multi-dose flu vaccines still contain thimerosal.
Additionally, the scientists recently obtained more insight into the mechanism by which thimerosal interferes with folate-dependent methylation. It acts by inhibiting the biosynthesis of the active form of vitamin B12 (methylcobalamin), which is of particular interest because doctors treating autistic kids are having good success with the administration of methycobalamin.
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Citation source: Molecular Psychiatry 2004 Volume 9, advance online publication doi:10.1038/sj.mp.4001476
For further information on this work, please contact Ms. Christine Phelan, Northeastern University, Pharmaceutical Sciences, 716 Columbus Avenue 5th Floor, Boston, Massachusetts 02120, USA; phone: 617-373-5455; FAX: 617-373-5383; e-mail: [email protected]
Molecular Psychiatry is published by the Nature Publishing Group. http://www.nature.com/mp
Editor: Julio Licinio, M.D.; phone: +1 310 825-7113; FAX: +1 310 206-6715; e-mail: [email protected]
For a copy of this article please contact Aimee Midei, e-mail: [email protected].
PLEASE CITE MOLECULAR PSYCHIATRY AS THE SOURCE OF THIS MATERIAL.
Re: Vaccines and ADHD and autism
Dad-What about the mercury load from eating fish contaminated with mercury? I wonder about the load in women, and pregnant women especially in states like CA where there is more fish to be eaten. And why aren’t adults, many like me who have received the flu vaccine year after year, developing autistic like symptoms? I understand that autism is a developmental disorder of course, and likely to be diagnosed at the time of language development.
Re: Vaccines and ADHD and autism
There is a difference in the properties of mercury depending upon which form it takes. Metallic mercury has beeen well established as neurotoxic, and is linked with a host of mental problems from acute exposure not the least of which is tendancy towards anti-social behavior (isolation, loss of interactive communication, aggressive tendancies), depression, and psychosis. Historically, we got the term “mad as a hatter” because of the use of mercury in curing the pelts from America and Canada which were shipped to Europe and made into hats. “Pink disease was quite common in this country around the turn of the centruy and stemmed from using teething powders that had mercury as a component.
Methyl mercury (found in fish) and ethyl mercury (thimerosal) are organic compounds and are significantly more neurotoxic than elemental mercury. There is a difference however in method of ingestion as to how much mercury is taken up into the body. When you eat contaminated fish, only about 10% of the mercury makes it into the bloodstream By contrast, 100% of the mercury present in vaccines makes it into the blood.
Another factor is that when adults get a flu shot (or any other shot with mercury in it) they have a body mass that is much greater than a newborn infant. The amount of mercury in the shot (assuming production quality is good and the nurse properly shook the vial) is about the same whether it is used in a baby or an adult, so wit the much greater mass, the adult faces a much lower exposure (think of two guys drinking beer; the fellow who goes 290 lbs is going to be able to drink a whole lot more before being impaired than the fellow sitting next to him who weighs 145.)
The most significant factor is that the brain and spinal column of a grown person is completely developed, so any mercury which makes it there will risk damaging a completed work, which has already learned to speak, tie shoes, drive a car, interact with other, do basic math, etc. The infant on the otherhand is still years away from having a fully developed central nervous system (this is why brain plasticity is possible, and is the reason for reading to your toddlers to make them easier to teach and is the basis for the entire Headstart program) and has not yet programmed its neural net to do things like speak and walk and count, etc.
Let me give you a very specific example… When my boy was 6 mos (give or take a week or two) he received 3 shots in one office vivit, DTaP, HiB and IPV, all of which contained thimerosal (the PDR says 25 mu per shot). The acceptable exposure (according to the EPA) is 10 mu per day (the FDA has a much higher threshhold). This represents a bolus exposure of 75 mu which for some unknown reason slipped by those who set the shot schedule. At that age my boy weighed about 20 lbs. For an adult to get a similar bolus exposure (assuming the person weighed 160 lbs) they would need to have 8 times that much, or 600 mu. I wonder how many of the people who flat out deny thimerosal is dangerous would allow themselves to have that much injected into them…
Another factor is in how our bodies handle toxic metals. We take metals into our bodies in trace amounts nearly daily. For the overwhelming majority of us, our bodies slowly detoxify, excreting them through the MT protein mechanism, and also sending them out in our hair and nails. Work conducted by Dr. Holmes and corraborated by Dr. Haley found that autistic children seem to lack this natural detoxification mechanism, and tended to retain all the metal that had been taken in.
One misconseption that you mention is worth noting.
<i>I understand that autism is a developmental disorder of course, and likely to be diagnosed at the time of language development.</i>
Autism is not likely to be diagnosed at the time of language development. This is commonly cited by people pushing a coincidental timing explanation to the vaccine-autism theory (which is actually centered around the MMR and not the thimerosal issue), but it is a complete falsehood. Autism is usually diagnosed much later than the typical age for language dvelopment (hence the basis for Sowell’s treatise “Late Talking Children”), usually close to age 5 (in the Atlanta Study of school aged children, 24% of the children with autism identified had not been diagnosed prior to starting school at age 5 and another 16% were not diagnosed until the CDC’s team did so, many as old as 8). Parents who ask about autism at the age when talking is expected (about age 2) are told to wait, each child developes at their own pace, it is too soon to worry, ect.
Re: Vaccines and ADHD and autism
ADHD existed in humankind long before vaccines were invented.
Attention deficits have many causes, one of which is heavy metal poisoning due to exposure to substances like lead et cetera.
Historically, vaccines are not the number one cause of ADHD.
http://www.nimh.nih.gov/publicat/adhd.cfm
http://www.aacap.org/publications/factsfam/noattent.htm
Re: Vaccines and ADHD and autism
I do not believe this article made the claim that ADHD was caused solely by vaccines, or that vaccines were the number one cause of ADHD. What they have done is shown how mercury injected in to children could cause neurological damage which would be consistant with the behaviors we associate with autism and ADHD. You yourself state that exposure to heavy metals can cause ADHD. Mercury is a heavy metal, and far more neurotoxic than lead, which you cite. It may be a case that the ADHD was preent,and the metals make it worse. It may be a case that mercury increases the caseload by triggering children who might otherwise not develope ADHD.
Time will tell… The pediatric vaccine supply should be thimerosal free sometime in the next year. Children with autism are typically diagnosed by about age 5, kids with ADHD shortly after that. So we should see drops in incidence by the end of this decade if thimerosal was indeed a trigger for either.
time of diagnosis
I disagree about the time of diagnosis now it is in toddlers and preschoolers…are you familiar with http://Firstsigns.org ?
Re: Vaccines and ADHD and autism
This is all so confusing to me. Our psychologist told us that if our son was brought in at the age of two he would have DEFINATELY gotten an Autism diagnosis. He had almost every characteristic. By age 3 1/2 our psychologist said that there is no way he is Autistic. I often wonder if our son is/was Autistic and early intervention helped him that much (we started therapy at two) or if two is too early to make such a diagnosis? I guess I’ll never know.
Diagnosis
You are probably confused for a very good reason. I have found that mental heath diagnosis is not anything close to an exact science. That’s coming from someone that has had to make some mental health diagnoses in my profession. I have seen people with 15 or 20 different diagnoses from different mental hospitals and clinics over the years. The diagnosis seems very dependent on the clinician. Also, people change over time (especially small children) so that the child may meet the diagnosis at one time and not later on, or vice versa. That’s the difficulty with using behavior as a diagnostic tool - there are too many variables to be precise!
But the good news is, whatever you did seems to have worked! That’s the bottom line. There’s no point having a diagnosis unless it helps you know what to do to make it better. And if you can make it better without the diagnosis, more power to you! Our oldest would certainly have been diagnosed with ADHD as a first grader. By 6th grade, he would have barely qualified, and by high school, not at all. So diagnosis of mental health issues is very inexact, and changes over time. The main thing to focus on is how to intervene. Once you have that figured out, the diagnosis becomes of secondary importance, IMHO.
–— Steve
My boy did not use expressive language until after we had treated him for mercury that the dr. said was not inside him, but which came out when we treated him. I do not think that thimerosal is the sole agent responsible for dramatic tenfold increase in autism or the nearly tripling of ADHD over the last 25 years, but I do think it is the most controllable fator in it. There has yet to be a study that disproves thimerosal as linked to autism and the studies which support the link are too small to be considered proving. 2004 represents the first year that all new shipments of pediatric vaccines are free from thimerosal (it is still in the flu shot and the tetanus booster as well as adult vaccines). Since the diagnosing of children with autism occurs on average at about age 5, we should see a drop in the rate by about 2009 if thimerosal is indeed a key factor in the epidemic.