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Environmental Epidemiology of Autism Research Network (EEARN)



Researchers use environmental epidemiological studies to investigate the potentially toxic substances that can increase the presence of a disease or disorder. The Environmental Epidemiology of Autism Research Network (EEARN) conducts these types of studies to investigate “the impact of environmental risk factors and their interaction with genetic predisposition to autism spectrum disorder (ASD).”1 Created in 2010, the network is sponsored by Autism Speaks and the National Institute of Environmental Health Sciences (NIEHS) and “brings together over 20 epidemiologic studies to improve communication between researchers in the field, identify opportunities for collaborative projects, and develop new research tools for existing and future studies.”2 Epidemiological studies, which can vary by design from studies that compare cases of ASDs to controls to those that compare different populations exposed to particular environmental factors, require multi-site and multi-disciplinary collaborations.1 This network of researchers has been conducting studies that focus on a variety of risk factors from exposures to air pollutants in the womb to preterm births. However, the cohort also investigates similar exposures during the perinatal period, which occurs during early childhood development.


The Formation of EEARN
In May 2010, the Environmental Epidemiology of Autism Research Network met for the first time in conjunction with the International Meeting for Autism Research (IMFAR) in Pittsburgh, PA. The creation of the network coincides with a March 2010 report from the National Institutes of Health that contains information about the type of research the U.S. government plans to conduct relating to autism. Included within these types of research study recommendations are ones that focus on “epidemiologic research on interactive genetic and environmental factors or processes that increase or decrease the risk for autism.”3 The initial meeting discussed the creation of EEARN as “an effort to accelerate research on environmental contributions to the etiology of autism spectrum disorder (ASD) and their interactions with genetic susceptibilities.”4 This initial meeting1set the foundation for EEARN and led to the development of the following goals:

  • Support and encourage collaborations across research sites, especially research projects that involve rare subgroups or exposures.

  • Provide a framework to share information and research protocols, including a website.

  • Create opportunities for new researchers, specifically in probing existing data for still uncovered findings.

*NOTE: EEARN’s website is run through a private platform between their networks of researchers and is not for public access.


EEARN Studies
EEARN studies focus on environmental factors’ perinatal and prenatal roles, as well as how environmental factors interact with genes. In 2012, Autism Speaks offered grants to fund two projects for a duration of two years, each with a total maximum budget of $300,000.5 The first of these studies, which is being conducted at Drexel University, is investigating the relationship between prenatal PBDE exposure and the risk of developing ASD.6 Polybrominated diphenyl ethers (PBDE) “are man-made chemicals used as a flame retardant in common items in the home, such as clothing, furniture, and electronics. Use of PBDEs is being banned in the U.S. over time, but the presence of these chemicals persists in our environment, evidenced by existence of PBDEs in blood.”6 The data from this study will be pulled from the Early Autism Risk Longitudinal Investigation (EARLI) Study, which “collects biological data and other information on mother during pregnancy and tracks the child[‘s] outcome and also collects biological information on the child.”6 This project is spearheaded by Craig Newschaffer, PH.D., the founding director of the A.J. Drexel Autism Institute and a professor in the Department of Epidemiology and Biostatistics at the Drexel University School of Public Health.7

The second of the 2012 EEARN grants is being utilized to study air pollution, MET genotype, and ASD risk.8 MET is a leading candidate gene for autism that is “expressed in several areas of the human brain that are active during social tasks.”9 This research is building off of previous findings that indicate air pollution increases the risk of ASD, such as this 2008 study, which found that “for every 1,000 pounds of mercury released by Texas power plants in 1998, there was a corresponding 3.7 percent increase in autism rates in Texas school districts in 2002.”10 The MET gene study8 will use prenatal blood obtained through the State of California to identify:

  • Genetic mutations of the MET receptor and whether these mutations affect association

  • Specific immune markers that may also contribute to risk.

This grant was awarded to Lisa Croen, PH.D., who is the director of the Kaiser Permanente Autism Research Program.


Another EEARN project was launched in 2011 with the goal of “discovering and characterizing risk factors for ASD, by developing, refining, validating, and feasibility testing a data-collection tool designed to assess medical and environmental exposures potentially relevant to ASD.”11 The findings of this project were reported on in May of 2013. The researchers “systematically reviewed the literature to identify ASD-relevant exposure domains with the potential for reliable and valid assessment in a self-administered parent survey. [The researchers] selected items corresponding to these domains…and grouped them into modules – diet/lifestyles, home environment, and maternal conditions/medical interventions – that can be used together or separately.”12 Ideally, this instrument will “allow for assessment of relatively rare gestational exposures and interaction effects, including gene-environment interaction… this instrument should facilitate collection and sharing of environmental exposure data among ASD investigators working with diverse populations using dissimilar study designs, enabling collaborations that would not otherwise have had the resources and/or expertise for such exploration.”12 The questionnaire will be piloted by participants in the Markers of Autism Risk in Babies – Learning Early Signs (MARBLES) study, and “responses will be compared with data previously collected prospectively during gestation to assess the reliability to retrospective recall.”12


The Importance of Environmental Factors
The dramatic increase of autism spectrum disorders seen in the last two decades lends much credence to the hypothesis that environmental factors are interacting with infants’ genes, both prenatally and shortly after birth to increase the risk of autism. The difficulty in pinpointing these environmental factors lies in their ambiguity. An environmental factor can essentially be anything. Past studies have focused on traffic pollution, parent’s age at conception, pesticides, vaccinations, viruses, water quality, and exposures in the womb, just to name a few. By focusing research on specific populations across the world, researchers may be able to collect data to determine which specific environmental exposures are responsible for the increased rate of autism in those particular regions.13 For example, if researchers are hypothetically studying a population that eats a diet primarily of fish that may cause an increased risk of mercury exposure and happens to have a higher prevalence level than normal for ASD, then researchers may be able to pinpoint mercury exposure as the environmental factor contributing to the increased autism diagnosis in this region. For more information about what is being done to investigate the link between autism and environmental exposures, please visit the Environmental Factors Initiative page.


Summary
While the etiology of autism is still unknown, research is beginning to shed light on how environmental factors interact with specific genes to increase the risk of developing autism. The flexibility of epidemiological studies allows researchers to explore a variety of potential risk factors in a number of different ways. The EEARN consortium spans the globe and continues to offer solutions and ideas to address the challenges in studying environmental epidemiology of ASD at the domestic and international level.14 The specifics of the 2013 EEARN meeting have yet to be released, but interested parties can browse the 2013 IMFAR meeting presentations here.


References