Autism and the Environment

The goal of the Autism and Learning Disabilities Discovery and Prevention Project, launched in May 2010, is to discover environmental causes of autism and other learning disabilities and to turn these scientific discoveries into evidence-based strategies for autism prevention.

One in six American children is afflicted with a developmental disability. In most cases, these disabilities affect the brain and nervous system. The most common are autism, learning disabilities, attention deficit hyperactivity disorder, dyslexia, sensory deficits, and cerebral palsy. Treatment of these disorders is difficult. They place great burdens upon families and are very costly to society. Their prevalence is on the rise. Autism now affects one in every 110 children in the United States.

Certain toxic chemicals have been shown to cause developmental disabilities in children. These include lead, PCBs, methyl mercury, and ethanol. Discovery of a specific environmental cause is the key to prevention. For example, discovery of the toxicity of low-level exposure to lead, a discovery in which researchers in our Center were centrally involved, triggered a decision to remove lead from gasoline and paint. These actions have produced a 90% decline in developmental disabilities due to lead. But for far too many developmental disabilities, the causes are not clear. Information on preventable causes is urgently needed.

In the case of autism, genetic causes are clearly implicated. They include gene mutations, deletions, and copy number variants. However, these genetic causes account for only about 25-30% of all cases of autism, and they do not easily explain key clinical and epidemiological features.

It is increasingly clear that environmental exposures also contribute to autism. Indirect evidence for environmental causation comes from studies demonstrating the exquisite sensitivity of the developing brain to toxic exposures in the environment. But the most compelling proof-of-concept evidence comes from studies that specifically link autism to exposures in early pregnancy – thalidomide; misoprostol; valproic acid; and the organophosphate insecticide, chlorpyrifos. While none of these particular chemicals are responsible for current trends in autism, their documented ability to cause autism establishes the principle that toxic exposures in early development can damage the brain to cause autism.

Likelihood is high that there are still other undiscovered environmental causes of autism and other learning disabilities. These undiscovered causes are most likely to be found among 1,200 industrial chemicals that are known to be toxic to the brain in adult humans and laboratory models, but have never been examined for toxicity to the developing brain.

Among these 1,200 chemicals, highest suspicion attaches to those that are:

  1. Most widely distributed in the environments of children and pregnant women; and
  2. Most commonly detected in the bodies of Americans in national surveys conducted by the Centers for Disease Control and Prevention.

Discovery Strategy
The following are the steps we will take in 2010 to begin the Autism and Learning Disabilities Discovery and Prevention Project:

  1. To refine our list of target chemicals, we will convene an international scientific workshop of leading experts in the fields of autism research, brain development, genetics, pediatrics, and neurotoxicology. The goal of the workshop will be to develop a strategy for research and to produce a ranked list of the most highly suspicious chemicals. This workshop is scheduled for Wednesday, December 8, 2010.
  2. To create a platform for future epidemiological and genetic studies, we are launching the Mount Sinai Cord Blood and Placental Tissue Repository. Collection of maternal blood samples during pregnancy and of cord blood and placental tissue samples at delivery, with subsequent follow up of children and families through this Repository, will enable us to trace connections between prenatal exposures, genetic susceptibilities, and the subsequent development of autism and other learning disabilities. Planning for the Repository is already far advanced, and two pilot grants from CEHC – one to develop epigenetic markers in placental tissue and the other to develop a novel placental biopsy instrument – have contributed importantly to its development. In June 2010, funding to support the next phase of development of the repository was awarded by the Hearst Foundation.
  3. To screen synthetic chemicals for potential ability to disrupt early brain development and thus increase risk for autism and other learning disabilities, we shall work with the Departments of Psychiatry and Neuroscience at Mount Sinai to develop an experimental model of disordered brain development. Development of this model will itself be a major contribution to science in this area.
  4. We will partner with the Department of Psychiatry to undertake prospective epidemiological studies of children exposed prenatally to suspicious chemicals. Some of these studies have already been launched with pilot funds provided by CEHC.
  5. We continue our leadership role in the National Children’s Study (NCS). It is anticipated that approximately 1,000 of the 100,000 children to be enrolled in the NCS will ultimately be diagnosed with autism or Autism Spectrum Disorders (ASD). We are involved in studies to link these diagnoses with genetic and environmental exposures in early life.

We anticipate that the Autism and Learning Disabilities Discovery and Prevention Project will be a multi-year effort. Philanthropic support will enable us to jump–start the project and to begin to collect pilot data that we then plan to use to catalyze major federal funding.

Scientific Workshop: Exploring the Environmental Causes of Autism and Other Learning Disabilities
On Wednesday, December 8, 2010, CEHC will hold a scientific workshop, Exploring the Environmental Causes of Autism and Other Learning Disabilities, at the New York Academy of Medicine. This one-day scientific workshop will bring together nationally and internationally recognized experts in causation of autism and other learning disabilities. Learn more about this symposium.

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