Environment Contributes to Autism, Not Just Genes

New Autism Report: Emphasizes Environmental Factors as Cause

New and controversial studies have been released suggesting a link to autism and the environment, including the environment in the womb.

California Autism Twin Study Suggests Prenatal Risk Factors Autism Speaks Official Blog

According to new research, autism could be caused by the environment. Scientists have been researching the push and pull that molds a growing brain. One study on twins that was published this week reported that the disease is about 60% environmental and 40% genetic. Other experts are disputing these links between environment and autism, still claiming that genes are the biggest cause of autism.
Twin Pairs With Autism Study, studied 192 pairs of twins in California – fraternal or identical – where at least one was affected by autism.

Using diagnostic techniques that included directly observing the children, scientists found 77 percent of male identical twins (from one fertilized egg) and 50 percent of female identical twins both had autism. These finding were not surprising since identical twins share the same genes.

The surprising findings in this study were the high rates of autism found in fraternal twins (un-identical twins from two fertilized eggs). Fraternal twins share no more genetic material than any other siblings; but they do share the same womb.

According to the research, these findings put a focus on environmental factors taking place during pregnancy. Factors could include stress, diet, infections, and a mother’s age.

Another study on Antidepressant Use During Pregnancy and Childhood Autism Spectrum Disorders, shows a possible link between the use of antidepressants during pregnancy and the development of autism.

This second study showed mothers who took antidepressants during the year before birth – particularly in the first three months of pregnancy – were more likely to give birth to children with autism. Specifically, 6.7 percent of women taking antidepressants gave birth to a child with an autism spectrum disorder, compared to 3.3 percent of women who weren’t taking antidepressants.

Environment Contributes to Autism, Not Just Genes

Earlier this year a report was released Linking Living near Freeways to Autism.
Researchers studied 304 children with autism and 259 children who were typically developing in California. Data was recorded on where each child’s mother lived during pregnancy and at the time of birth, and the proximity of the homes to a major road or freeway.

Children living about 1,000 feet from a freeway at birth (10% of the sample) had a two-fold increase in autism risk. The link held up even after researchers controlled for other factors that may influence development, such as ethnicity, parental education, maternal age and exposure to tobacco smoke.

The findings in all these studies are counter to recent research which has focused more heavily on genetic causes. Some experts are even questioning the findings on these recent studies.
“I think they’re really on shaky ground to say that,” said Dr. Paul Law, director of the Interactive Autism Network at the Kennedy Krieger Institute in Baltimore.
“It’s a massive claim,” said Angelica Ronald, a behavior geneticist at Birkbeck University of London. “It flies in the face of the previous data. I don’t see why the results have come out the way they have.”
The study authors acknowledged that their calculations were subject to a wide margin of error and thus could be incorrect. However, these findings merit more research into environmental factors.
Learn More About Autism

As scientific research continues on the cause or causes of autism, parents whose children are diagnosed can often times feel guilty or blame themselves. It is important to remember that no matter what research is uncovered, the most productive action for parents is to focus on treatment options and advocacy of services for their child.

Mothers should consult with their doctor first before they stop taking their antidepressants or other changes to their routine, non treatment of depression during pregnancy has its own risks. Make an appointment to speak with your doctor about the release of these new studies and how to address this during your pregnancy.

References:
“Autism triggered by environmental conditions, not just genes, says studies”. CBS News, July 5, 2011
“Autism study down plays role of genetics”. Los Angeles Times, July 5, 2011
“Living Near Freeways May Increase Risk of Autism”. Abilitypath.org

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