The origins of autism have always been a mystery to doctors and researchers, but now, perhaps part of that mystery has been solved.
Autism begins during pregnancy, according to researchers from UC San Diego and the Allen Institute of Brain Science in Seattle.
Researchers spent the past nine years looking into which region of the brain is associated with autism, and they have concluded that autism begins during pregnancy with disruption to the brain's cortex. The study also identified abnormal gene activity showing how that disruption causes autism.
This discovery could allow scientists to better tailor autism therapies and prevention, according to the researchers.
The study showed that the regions affected by the disruption during pregnancy are the frontal and temporal cortex. Researchers found the abnormalities by looking for 25 genetic markers found in brain cells as well as genes linked to an increased risk of autism.
"We discovered that brain evidence that autism begins in the second or third trimester during pregnancy, and we found that the brain systems that are disrupted and fail to form the correct structures at that early time are the systems that are important for social language and communication, the very functions that are disrupted in autism," said Eric Courchesne, the director of UC San Diego's Autism Center of Excellence and one of the senior authors of the study.
The study compared brain samples of deceased children with autism to deceased non-autistic children, ages 2 to 15. Researchers found that about 91% of the autistic children had disruptions in sections of the brain samples, compared to only 9-percent of non-autistic kids. There are six layers in the cortex, which are all developed during pregnancy.
Researchers said past studies of adult brains may have missed childhood abnormalities, which means finding these signs in the brains of children is important. The brains of children with autism are enlarged, but the overgrowth disappears by adulthood.
This study from UCSD and the Allen Institute of Brain Science comes just as officials from Centers for Disease Control and Prevention announced that 1 in 68 children in the United States has autism, a 29% increase since 2008. It's unclear from the CDC study whether autism is becoming more common or simply more recognized and diagnosed now.
The study on autism and pregnancy was published in the New England Journal of Medicine. Eric Courchesne of UC San Diego and Ed Lein of the Allen Institute for Brain Science in Seattle were senior authors. Maggie L. Chow, Rich Stoner, and Maureen P. Boyle, all from UC San Diego, were first authors.
Scientists say that the discovery allows them to look into therapies on a molecular level and possibly even medications.
Perhaps the biggest hope to result from it is help for future children.
Researchers say because autism could be caused by an abnormal genetic activity, it can possibly be pinpointed and prevented.
More genetic mapping and work has to be done before scientists have a full map of an autistic brain. Courchesne said they are now working on the next phase of the study, which will look at what causes autism.