Genes play an undeniable role in what causes autism in children. But a new study published in the Archives of General Psychiatry concludes that environment plays at least an equal — if not bigger — role.
This is not such good news for the modern mother, who is typically older, more stressed out, more likely to have multiples and, let us not forget, completely awash in all kinds of crazy chemicals through no fault of her own. Previous research has attributed these an other environmental factors as possible reasons for an increase in the number of kids diagnosed with autism in the last few decades.
Alan Zarembo, who covers autism for the LA Times, explains how researchers came to focus on genetics when studying autism in children. In past twin studies, they found that the more DNA multiples shared, the more likely both would have autism than just one — 80 percent or higher for identical twins, who share 100 percent of their DNA; 10 percent or less for fraternal twins, who share only half of their DNA.
But as the definition of autism expanded to include milder forms of the disorder, more fraternal twins (the half DNA sharers) started showing an increased risk in both having some form of autism — more than 30 percent.
So Dr. Joachim Hallmayer, a psychiatrist at the Stanford University School of Medicine and his team of researchers took boy twin studies numbers and plugged them into a computer model that was designed to tease apart the risk factors of genetics vs. environment. And that’s where this new, and controversial conclusion, comes from. The computer model found that less than 40 percent of the risk for autism could be attributed to genes while 55 percent of the risk could be attributed to environment.
Other scientists aren’t convinced and say that there’s nothing really new except for Hallmayer’s conclusion.
Zarembo points to another study published in the same journal that found mothers who were taking SSRI antidepressants during pregnancy had babies who were at a slightly higher risk in being diagnosed later with some form of autism.
As it stands, scientists still haven’t found a smoking gun in what causes autism. The authors of this new study, and most others who work in autism, think there’s a mix of both genetics and environment. While this isn’t satisfying for worried parents — and those seeking answers — at least research has brought us beyond the point of blaming cold mothers who failed to form attachments to their children.
Photo: hepingting via flickr