Environmental Causes of Autism and the Existence of an Autism Epidemic

If you can believe some professors of cultural anthropology and classical literature there are no environmental causes of autism and there is no autism epidemic. ALL of the dramatic increases in the numbers of autistic children and adults are due ENTIRELY to the definition changes in the DSM and to diagnostic substitution. Bringing their powers of personal opinion, societal observation and literary analysis to bare on the subject they have concluded that there is no autism epidemic.

We can all rest easy now that the rumor of an autism epidemic has been thoroughly discredited by these uh .... giants of science. No need at all for parents to worry about mercury, lead, pesticides and other harmless substances to which we as DNA bearing parents or our children themselves might be exposed. We can all rest assured that autism is purely genetic. Any and all increases in cases of autism must be due entirely to definition change, diagnostic substitution, increased awareness etc. According to the true believers autism has only genetic causes and there is nothing we can do to treat or cure our autistic children. Que Será Será.

Of course there are heretics out there, unbelievers who have not yet seen the light, people who actually give credence to theories about global warming. People who are concerned generally about the increasingly toxic bath into which each new generation is born. I must confess to being one of those heretics. While the genetic bases of autism are becoming known with increasing specificity the role of possible environmental cause or triggers of autism has not been eliminated. Far from it.

Studies of twins have established that it is not 100 per cent genetic, since even among identical twins, when one has autism, the likelihood of both twins having autism is only about 60 per cent. This means there must also be an environmental component, but what it is remains unknown.

Simon Baron-Cohen, Freedom of Expression, TimesOnLine, December 14, 2007

A recent article in Pediatrics, Official Journal of the American Academy of
Pediatrics, by authors Bruce M. Altevogt, PhD, Sarah L. Hanson, BA and Alan I. Leshner, PhD also addresses the mix of genetic, biological and environmental stressors. All three authors are members of the Forum on Neuroscience & Nervous System Disorders, Institute of Medicine, Washington, DC. Dr. Leshner is also associated with the American Association for the Advancement of Science, Washington, DC. In the abstract for Autism and the Environment: Challenges and Opportunities for Research, PEDIATRICS Vol. 121 No. 6 June 2008, pp. 1225-1229 (doi:10.1542/peds.2007-3000) , it was stated that:

Autism spectrum disorder is a complex developmental disorder that dramatically affects the lives of patients and their families and the broader community. The causes of autism are unknown; however, evidence increasingly suggests that a complex interplay among environmental stressors, genetic mutations, and other biological factors likely plays a significant role in the development and/or progression of autism spectrum disorder. [bold highlighting added - HLD]

In Environmental Factors and Limbic Vulnerability in Childhood Autism American Journal of Biochemistry and Biotechnology 4 (2): 183-197, 2008 Dr.Richard Lathe of Pieta Research, Edinbugh, expressly argues against diagnostic substitution as a complete explanation for the current prevalance of autism spectrum disorders and stresses the likelihood of substantial environmental contributions:

The rise in prevalence of autism spectrum disorders (ASD) is suggestive of a
new etiology. Diagnostic substitution alone is unlikely to account for the increase, while genetic association with detoxification gene alleles points to an environmental contribution. Subtle structural anomalies in the ASD brain are widespread but limbic damage seems important for the development of behaviors diagnostic of ASD. The limbic brain is especially susceptible to environmental challenge: internal sensing, physiological feedback and neuroinflammatory processes may underlie this sensitivity to insult. Primary damage leading to ASD in later life is likely to take place in utero and/or in the immediate postnatal period. Despite evidence of heavy metal involvement, a causal connection may not yet be concluded because subjects exposed to metals tend to be exposed to other environmental agents. Because maternal minerals and lipids are supplied to the unborn child, historic toxic exposure of the mother may be pivotal. A two-hit combination of genetic susceptibility and environmental challenge is argued to underlie the rise in ASD.

Personally, I believe that we are in the midst of an Autism Knowledge Revolution in which science, not the ancient Greeks, or superficial and irrelevant cultural comparisons, will determine with increasing certainty the causes of autism, be they genetic, environmental or some combination of factors. As that knowledge increases debates about whether we are living in an autism epidemic should also be decided with greater certainty.

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Autism, Genetics and Environment - Study Finds Autism Immune System Link

A study reported in the January 2008 issue of Genomics, Gene expression changes in children with autism, has found that a group of genes with known links to natural-killer cells, that attack viruses, bacteria and malignancies, are expressed at high levels in the blood of children with autism when compared to children without the disorder. The study also found gene expression distinctions in children with early onset and regressive autism. The study is summarized in a digestible format on the UC Newsroom article Researchers identify gene expression profile distinctions in children with autism. Comments by the senior researcher Frank Sharp M.D. clinical neurologist, neuroscientist, and professor, department of neurology, school of medicine, indicate that the findings suggest a possible environmental role in the development of autism disorders:

"What we found were 11 specific genes with expression levels that were significantly higher in the blood of children with autism when compared to the blood of typically developing children," said Frank Sharp, senior author of the study and professor of neurology with the M.I.N.D. Institute.

"Those 11 genes are all known to be expressed by natural-killer cells, which are cells in the immune system necessary for mounting a defense against infected cells. We were surprised by our results because we were not looking for these particular genes. And while a number of studies have shown immune system dysregulation to be an important factor in autism, ours is one of the first to implicate these particular cells."

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"What we are seeing can reflect something in the environment that is triggering the activation of these genes or something genetic that the children have from the time they were conceived," Sharp explained. "Such an immune response could be caused by exposure to a virus, another infectious agent or even a toxin.

Another possibility is that these changes represent a genetic susceptibility factor that predisposes children to autism when they are exposed to some environmental factor." He added that the current study also does not identify whether or not the natural-killer cells are functioning abnormally, which further work by M.I.N.D. Institute immunologists will reveal. "If the natural-killer cells are dysfunctional, this might mean that they cannot rid a pregnant mother, fetus or newborn of an infection, which could contribute to autism."

The study is also featured in an article by Carrie Peyton Dahlberg at sacbee.com which features several interesting comments by Dr. Jeffrey Gregg, director of molecular diagnostics for the UC Davis Medical Center who was also involved in the study. It is pointed out that both similarities and differences were found between the early onset and regression autism cases:

Children with that "regressive" autism had nearly 500 genes that were activated differently than children with "early onset" autism, Gregg and his colleagues found after examining blood samples from 61 children.

"That would suggest that those two groups are very different … and may have totally different underlying pathology," Gregg said.

Both groups, though, as well as other children with a range of symptoms called autism spectrum disorder, shared the 11 strongly expressed genes that control natural killer immune cells.

Dr. David Amaral, the UC Davis MIND Institute's research director suggested that much remains to be learned about how the genetic and environmental factors giving rise to autism interact:

It is still unclear how early those differences emerge, but other MIND Institute researchers are looking at immune differences in mothers' bloodstreams that might be predictive for having a child with autism, said Dr. David Amaral, the institute's research director.

"Things are moving really, really fast now," Amaral said, with scientists around the country working to understand the relationship of genetic and environmental factors that may underlie autism.

It seems clear from this study that environmental factors can not be ruled out in trying to understand the causes -- and potential treatments for autism. Some of the rhetoric which dismisses all genetic or all environmental factors appears to be ill founded. The Autism Knowledge Revolution is being carried out by researchers and scientists in relevant medical fields and the knowledge they are gaining appears to point to both genetics and environment as being involved in the development of autism.

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Autism and Lead Poisoning

The focus on a mercury based preservative in some vaccines has taken public attention away from other commonly found toxic substances as possible causes, or contributing factors, in at least some of the increasingly large numbers of autism diagnoses being made today in the Canada, the US, the UK and elsewhere in the world. Yesterday CBC news carried a story Excessive lead found in water of 5 Toronto schools which as the title indicates, reports on five Toronto area schools in which testing showed the water supply exceeded the Ministry of the Environment standard of 10 micrograms of lead per litre. The school district is now supplying staff and students at the 5 schools with bottled water.

The article also notes in conclusion that "Childhood exposure to lead can cause learning problems and reduced intelligence." The CBC article also contains a link to the Ontario Ministry of the Environment web page which notes that, apart from lead pipes and drinking water there are many other sources of lead in our environment including some older lead paints. As we have learned recently lead is still being found in some popular children's toys. With respect to the health effects of drinking lead contaminated water the Ontario Environment Ministry page Lead and Drinking Water - Questions and Answers states that:

How does lead in water affect health?

Young children are more sensitive to the effects of lead because they are still developing and able to absorb ingested lead more easily than adults. Long-term exposure to lead above the standards may increase the risk of subtle impairment of learning capacity and intellectual development. Pregnant women need to limit their lead intake as much as possible to protect the fetus.

In Autism and Autistic Symptoms Associated with Childhood Lead Poisoning , published in the Journal of Applied Research, authors Theodore I. Lidsky, PhD , Department of Psychobiology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York and Jay S. Schneider, PhD Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University College of Medicine, Philadelphia, Pennsylvania examined two case histories of children who, during periods of severe lead poisoning, developed autism or autistic symptoms.

In the abstract portion of the article the authors noted that "These cases underscore that there are multiple causes of autism and the importance of environmental influences in some cases."
Both of these children emerged from their autism diagnoses (1 autism disorder, 1 PDD-NOS) with the passage of time but with no specialized treatment. Lidsky and Schneider concluded that:

The two case histories presented here, as well as the reports of autistic symptoms in children with disorders that produce brain lesions or encephalopa- thy, indicate that there are multiple causes of autism. Further, the ability of brain infections and lead poisoning to produce such symptoms highlights the importance of environmental factors in the etiology of *autism*.

The ability of *lead* *poisoning* to induce symptoms of *autism* is also relevant to cases of preexisting pervasive developmental disorders irrespective of etiology. Such individuals have a greater propensity to engage in pica and, as a result, are more likely to become *lead* poisoned.

In such cases, *lead* poisoning can be expected not only to negatively impact neurocognitive functioning, but also to potentially exacerbate the preexisting symptoms of *autism*. Indeed, one case report describes a decrease in hyperactivity and stereotypies in an autistic child with a blood *lead* of 42 µg/dL once this level was reduced by chelation with succimer.

In June of 2007 Dan Agin discussed the possibility of lead poisoning as a major environmental factor in autism on the Huffington Post in his article Autism and Our Passion For Simple Causes and Quick Fixes. Mr. Agin's Huffington biography states that he has a Ph.D. in Biological Psychology and thirty years laboratory research in Neurobiology. He's Emeritus Associate Professor of Molecular Genetics and Cell Biology at the University of Chicago, and for the past ten years he has been editor-in-chief of the journal ScienceWeek (www.scienceweek.com), a science digest that focuses on explicating new research in the various sciences.

No one can credibly claim that autism is purely genetic or purely environmental. The unified autism theory seems to suggest that both types of factors are involved in the development of genetic mutations giving rise to autism. There is much research to be done, and much being done, on all sides in the search to understand what causes autism. We know there are major toxic substances, including mercury and lead, polluting our environment. It would be foolish to ignore them as possible causes of autism. It would also be foolish to pretend that the research on these issues is complete and that any of these toxic substances can be ruled out as causes of autism.

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Autism Researcher Dr. Michael Wigler - Who Is He?

The world of autism research is being rocked on an almost daily basis as the Autism Knowledge Revolution has wrested control of the world discourse on autism away from personal biases and opinions and placed it back in the ambit of solid scientific research. Dr. Michael Wigler and the Cold Spring Harbor Laboratory have been at the forefront of this explosion of autism research with their development of the genetic mutations explanation of autism. But who is Dr. Michael Wigler? Newsday provides an introduction and details his impressive background in mathematics and cancer research.

" Michael Wigler, the geneticist leading Cold Spring Harbor Laboratory's search for the genetic basis of autism, is a celebrated scientist who has made significant contributions to the molecular understanding of cancer.

Observers say it is his rare ability to see mathematical patterns in the complexities of genes that allow him to produce new ways of understanding disorders that underlie human debilities.

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Having conducted research at the lab for 30 years, Wigler was in the forefront of scientists who developed the tools to probe cancer's DNA. He's also co-discoverer of the first human oncogene, a molecule capable of transforming normal cells into malignant ones. His work at the lab also led to the development of ROMA - representational oligonucleotide microarray analysis - a highly sensitive technique that allows scientists to profile the genetic basis of cancer and other diseases.

"Michael grew up as a mathematician and began to indulge in genomics," which required a strong mathematical background, said Dr. Mary-Claire King, the world-renowned medical geneticist at the University of Washington. She led the research team that discovered the breast cancer gene, BRCA1 and collaborated with Wigler on his initial work focusing on spontaneous mutations in autism.

Full Article at:

http://www.newsday.com/news/health/ny-hsside125331616aug14,0,6247673.story

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Early treatment of autism hinges on genetic discoveries

Much attention has been paid to purported environmental causes of autism. Controversy has raged over both the MMR vaccine itself and the use of thimerosal, a mercury based preservative used in vaccines as a potential cause of autism.

As prominent a figue as Robert Kennedy Jr has pushed the thimerosal theory before the US Congress and the world. There is however precious little scientific support to date for the vaccine/thimerosal theories. Recent environmental theories include Lyme Disease and television as possible causes of autism.

Notwithstanding the focus on potential environmental causes of autism it is heartening to read that research continues on genetic factors. Genetic research is an important element to the early identification and treatment of autism including development of specific treatments for individual autistic persons as discussed in a very readable article by Dr. John Bernard, president of the Children’s Research Institute, published in the Columbus Dispatch:


"Identical twins have identical genes, while fraternal twins are genetically similar, but not identical. When identical twins have autism, both are affected about 60 percent of the time, whereas fraternal twins are both affected only about 5 percent of the time.

These findings strongly suggest a genetic basis for many cases of autism.

But current thinking is that autism spectrum disorders do not result from genetic factors alone. It is likely that unknown environmental factors also are involved, perhaps as a result of genetic susceptibility.

It is probable that each of the autism spectrum disorders is associated with a specific genetic abnormality. However, scientists involved in the search for specific genetic abnormalities in autism are challenged by the complex variability of individual cases.

Unless individual children can be accurately and specifically classified within the autism spectrum, the search for underlying genes is clouded. Fortunately, specific genetic abnormalities are now being discovered for some of the rare and distinctive types of autism spectrum disorders.

Discovering specific genetic abnormalities associated with autism spectrum disorders might help detect them earlier in life than currently is possible.

Children then could receive customized treatment programs at the earliest possible age, when the prospect for success is best. It is also possible that drug treatments can be designed by researchers to specifically modify the genetic abnormality involved. "

http://www.dispatch.com/science/science.php?story=dispatch/2007/01/16/20070116-D5-04.html

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