When it comes to autism, ADHD, and learning disabilities, genetics is only part of the story. In fact, in trying to figure out what causes autism, researchers are proving that environmental factors—everything from farm chemicals to soda and shampoo ingredients—could be permanently messing with children’s brain development.
Autism’s Most Common Cause: Environmental Factors
The largest and most rigorous twin study of its kind finds environmental exposures among the leading causes of autism. By LEAH ZERBE. Reprinted from http://www.rodale.com/causes-autism-0
Today, in an unprecedented move, some of the world’s leading experts published a new list of highly suspect chemicals and heavy metals believed to be behind the surge in cases of autism and other neurodevelopmental diseases. “We have very powerful, very sophisticated tools we can use to measure chemicals at very low levels,” explains Phil Landrigan, MD, coauthor of the list and professor and chair of preventive medicine at Mount Sinai Medical School in New York. “It’s now possible to connect early exposure to problems in childhood.” The study is published in Archives of General Psychiatry,
Dr. Landrigan says the goal of the list, published in Environmental Health Perspectives, is to inform more doctors and nurses about the environmental triggers of autism, to increase funding for more studies, and to ultimately change chemical regulation in this country to better protect our children.
A large study released this week found that environmental factors are more responsible forautism than previously believed. In fact, environmental exposures are now believed to trigger autism more commonly than genetic factors. Researchers did not investigate which particular environmental exposures are linked to autism, although that is an emerging focus among autism experts. This latest research studied identical and fraternal sets of twins. Twins are important in autism research, because studying them helps researchers separate genetic and environmental factors that may affect autism. Identical twins have the same genes, while fraternal twins share just 50 percent of the same genes, but share the same environment in the womb.
Autism experts not involved in this particular study say the research is well done, and could help further turn the tide of autism research toward recognizing that environmental chemicals and certain drugs could be causes of autism. “It’s very credible stuff,” says pediatrician and epidemiologist Phil Landrigan, MD, professor and chair of the department of community and preventive medicine at Mount Sinai School of Medicine in New York City. “As new information comes in, it’s becoming very clear that there’s environmental contribution.”
THE DETAILS: The study, published in Archives of General Psychiatry, studied nearly 200 sets of twins, some identical and some fraternal. At least one child in each set of twins had been diagnosed with autism. The researchers determined that fewer than 40 percent of the cases were caused strictly by genetics. Shared environmental factors, including exposures in the womb, were implicated in nearly 60 percent of the cases. A separate study published in the same journal issue found a doubled risk of autism in children whose mothers took SSRI antidepressants a year before giving birth.
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