Researchers at the University of California Davis have identified 10 regions in the Golden State with autism clusters -- areas where rates of autism among children are higher than average. The study has reignited the often-controversial debate about the causes of autism, including the role environmental "triggers" may play.
According to the UC Davis scientists, the two factors that most correlated to the presence of the clusters were parents with above-average levels of education and living near large autism treatment facilities. The researchers said they did not see evidence of environmental toxins being behind the clusters, which were mostly in heavily populated parts of Southern California, with some in the Bay Area.
The study looked at all 2.5 million births in California from 1996 to 2000, including about 10,000 children diagnosed with autism spectrum disorder, which the Centers for Disease Control and Prevention (CDC) describes as affecting people with "significant impairments in social skills and communication. They often have repetitive behaviors and unusual interests."
The Daily Green spoke with Dr. Cathy Pratt, who was not affiliated with the UC Davis study, but serves as director of the Indiana Resource Center for Autism at the Indiana Institute on Disability and Community at Indiana University. She is also chair of the National Autism Society. "I wouldn't be surprised if you saw a higher autism cluster near treatment centers, or that families that are more affluent are living near those centers. People with children who are autistic would be more likely to move to be near them to take advantage of their services," said Pratt. "According to a recent study by the CDC, the incidence of autism is now 1 in 110, and they're finding that it's an equal opportunity disability," she added.
Pratt said she had looked at the states with higher incidences of autism a few years ago, including North Carolina, New Jersey and her state of Indiana, and noticed that they also have more long-term autism programs. (Interestingly, they also have above average toxic burdens, especially in the cases of Indiana and New Jersey.)
"Families who are more affluent would have better access to diagnosis," added Pratt, who points out that it is often a challenge to get information about autism out to disadvantaged communities.
This point is thought provoking, because debate has raged for years about whether increased awareness, and expanded definitions of autism disorders, are largely to blame for the recorded upswing in cases. In fact, the CDC has estimated the odds for autism among boys as high as 1 in 60 now. The HHS's Maternal and Child Health Bureau's "2007 National Survey of Children's Health," published in the journal Pediatrics, showed 1 in 91 children between the ages of 3 and 17 with autism.
But last January, UC Davis researchers released a study in which they concluded that "California's sevenfold increase in autism cannot be explained by changes in doctors' diagnoses and most likely is due to environmental exposures. They concluded that changes in how and when doctors diagnose the disorder and when state officials report it explained less than half of the increase of autism seen in the past 15 years.
For her part, Pratt said she believes the increases "are due to a number of things; expanded diagnosis, increased awareness and an increase that's really happening. Exactly why is the billion-dollar question," she added. "We are looking at genetic disposition, and what's the trigger? We'll probably have a spectrum of causes." Dr. Susan L. Hyman, associate professor of pediatrics and an expert on neurodevelopmental and behavioral pediatrics with the University of Rochester Medical Center, told The Daily Green that variability in autism rates among states "may in part reflect environment and in part the culture for diagnosis." Hyman added, "There also may be environmental differences at play that are not continuous geographically."
Researchers have looked at many potential triggers, including exposure to pathogens or toxins shortly after birth, fetal damage from medications or infections, damage during the birthing process or, most controversially, early childhood vaccines (links to which have been elusive).
Much more research is needed on the causes of autism, though some parents do take some comfort in trying to avoid as many toxins as possible during vulnerable years. Another issue we should be looking at as a result of the UC Davis study, according to Hyman, is "How do we provide autism support services to all the areas that aren't near major treatment centers?"
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