Tuesday, May 29, 2012

A Focused Environmental Autism Research Strategy Is Needed

If you have a child who is severely affected by an autism disorder, whose ability to understand the world is limited, who wanders into dangerous traffic, lakes or rivers,  is prone to seizures or  engages in serious self injurious behavior autism is not just an alternative way of thinking or an opportunity to build a career mouthing empty feel good cliches about autism acceptance on twitter.  If you are a parent with a severely autistic child you will probably fight for evidence based autism interventions, accommodation in the schools for autistic students and a place for them to live with dignity as you grow old and ultimately die.  These are the harsh realities faced by  parents with low functioning autistic children who must look at autism seriously and not as an opportunity to tell the world that everything problematic about autism is solved if we all just accept autism in our child. For many parents we would like to see solid scientific research into all the causes and conditions that create autism in our children, genetic and environmental causes.

Autism may be prevented, treated or even cured in the future if the research is done.  If that research leads us to the age of the father in some cases then that is important to know. If that research leads us into the multitude of possible impacts on children while in the incredibly important environment known as the womb then that research must be done.  What will not help in understanding autism is simply throwing our hands up in the air and arguing that we should not conduct research on the prenatal environment or in mocking attempts to research possible environmental causes of autism as some Neurodiversity bloggers like to do.  

For many of us our child's Autistic Disorder is a serious, life impairing disorder, and a mystery  that must be solved by solid research, genetic and environmental. Environmental research has been short changed and a solid environmental research strategy is required as recently advocated by Philip Landrigan and his colleagues in A Research Strategy to Discover the Environmental Causes of Autism and Neurodevelopmental Disabilities. Landrigan and his colleagues Luca Lambertini and Linda Birnbaum of the Children’s Environmental Health Center, Mount Sinai School of Medicine, New York and NIEHS and NTP, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina.  

The distinguished authors argument includes a "proof of principle" segment in which they list studies linking various toxic substances to neurodevelopmental impairments:

"Exploration of the environmental causes of autism and other NDDs has been catalyzed by growing recognition of the exquisite sensitivity of the developing human brain to toxic chemicals (Grandjean and Landrigan 2006). This susceptibility is greatest during unique “windows of vulnerability” that open only in embryonic and fetal life and have no later counterpart (Miodovnik 2011). “Proof of the principle” that early exposures can cause autism comes from studies linking ASD to medications taken in the first trimester of pregnancy—thalidomide, misoprostol, and valproic acid—and to first trimester rubella infection (Arndt et al. 2005Daniels 2006).

This “proof-of-principle” evidence for environmental causation is supported further by findings from prospective birth cohort epidemiological studies, many of them supported by the National Institute of Environmental Health Sciences (NIEHS). These studies enroll women during pregnancy, measure prenatal exposures in real time as they occur, and then follow children longitudinally with periodic direct examinations to assess growth, development, and the presence of disease. Prospective studies are powerful engines for the discovery of etiologic associations between prenatal exposures and NDDs. They have linked autistic behaviors with prenatal exposures to the organophosphate insecticide chlorpyrifos (Eskenazi et al. 2007) and also with prenatal exposures to phthalates (Miodovnik et al. 2011). Additional prospective studies have linked loss of cognition (IQ), dyslexia, and ADHD to lead (Jusko et al. 2008), methylmercury (Oken et al. 2008), organophosphate insecticides (London et al. 2012), organochlorine insecticides (Eskenazi et al. 2008), polychlorinated biphenyls (Winneke 2011), arsenic (Wasserman et al. 2007), manganese (Khan et al. 2011), polycyclic aromatic hydrocarbons (Perera et al. 2009), bisphenol A (Braun et al. 2011), brominated flame retardants (Herbstman et al. 2010), and perfluorinated compounds (Stein and Savitz 2011).

Toxic chemicals likely cause injury to the developing human brain either through direct toxicity or interactions with the genome...."

Landrigan, Lambertini and Birnabaum generated a list of 10 chemicals that they recommended as priorities for investigation.  They expressly stated that the list is not intended to be exhaustive but is intended to provide a strategic environmental research focus to catalyze new evidence based programs for prevention of neurodevelopmental disorders in children. The  list includes some very well known dangerous substances:

  1. Methylmercury (Oken et al. 2008)
  2. Polychlorinated biphenyls (Winneke 2011)
  3. Organophosphate pesticides (Eskenazi et al. 2007London et al. 2012)
  4. Organochlorine pesticides (Eskenazi et al. 2008)
  5. Endocrine disruptors (Braun et al. 2011Miodovnik et al. 2011)
  6. Automotive exhaust (Volk et al. 2011)
  7. Polycyclic aromatic hydrocarbons (Perera et al. 2009)
  8. Brominated flame retardants (Herbstman et al. 2010)
  9. Perfluorinated compounds (Stein and Savitz 2011).

Landrigan, Lambertini and Birnbaum recognize the importance of genetic research but, as other learned authorities have noted, genetic research has received the overwhelming share of autism research dollars. The recent IMFAR conference in Toronto left me with the impression that the "it's gotta be genetic" trend of channeling autism research overwhelmingly toward genetic research  is continuing. As these learned authors have argued so compellingly it is critically important that environmental autism research be focused .... and funded ... if autism disorders are to be prevented, treated or cured in future.


Unknown said...

Thank you for your post Harold. I too was left with the impression that "it's gotta be genetic" trend at IMFAR in Toronto. Of most concern is all the information we read and heard about de novo gene mutations. These are mutations found in the child with autism but are not found in their parents. The researchers now need to focus on the environmental factors that are causing these de novo gene mutations.

Maya M said...

Environmental factors causing mutations have been known for many decades.
Some mutations are also spontaneous.