A study published on March 27 in the New England Journal of Medicine shows the first direct and clear evidence that autism begins before birth. The study, a joint effort between the University of California San Diego (UCSD) and the Allen Institute for Brain Science, looked at post-mortem brain tissue from 22 children between the ages of 2 and 15. 11 of the children had been diagnosed as autistic during their lives, and the control group consisted of another 11 who had not exhibited any autistic tendencies.
12,000 slides containing tissue samples from the cerebral cortex (the brain’s outer layer) were studied in a very labor-intensive process. Rich Stoner, the study’s lead author, created the first ever 3D model of the cortex to show the particular locations on the cortex where results were found. What was found is definitive evidence that autism begins in utero when the brain’s cells are forming to become their end product. This most likely occurs during the second and/or third trimesters, according to authors of the study.
The cortex is made up of six layers. As cells develop in the various layers and across various regions, each cell is designated what is called a biological marker. Basically this means that each cell starts out the same, but depending on its location on the cortex, genes tell each cell what to become: whether a language cell, a movement cell, and so on. Cells, therefore, will develop uniformly within their given region in a normal brain. Researchers found in the brains of 10 out of 11 of the children with autism, and interestingly also in one of the 11 without, there are two-inch sized patches where cells were either not designed a marker, or the message did not get through. This means they stayed in their essentially infant form, not going on to evolve into function-specific cells. The patches which were affected across all of the affected brains were areas to do with language, communication, social comprehension and emotion, all areas that children with autism show impairment in.
Although the patches were generalized to the same areas of the brain, they were not necessarily uniform in size and depth (across the same number of the six layers of cortex). One of the researchers, Eric Courchesne, says this would account for why the autism spectrum is so wide, with some children having much greater challenges than others. Why the disruption in cell development begins in the first place, meaning whether it is because the related genes in cases of autistic children are flawed in a way as to stop the respective cells from developing, or whether something environmental triggers what is only a possibility, remains unclear.
Scientists are very encouraged by this find, as further studies will be better-targeted, and a cause for autism is perhaps closer to being known. Currently no cause is known, nor is there a cure. Treatments include behavioral therapy or medication, or a combination. However the findings of this study do explain why early intervention has been shown to be crucial in autistic children. The greater flexibility of young cerebral neurons may allow for actual reconnections within the brain to be triggered by therapies, though these same connections in cell development had remained dormant when left to their own devices. Also, if markers for why this happens can be found conclusively, it means even earlier intervention could be possible.
Currently children exhibit the first clear signs of autism between the ages of two and five, and are often diagnosed around or after the age of three. If children can one day be diagnosed in utero or soon after birth it means intervention can begin right away, and who knows how many brain reconnections might be made then.
By Julie Mahfood
Follow Julie Mahfood on Twitter @JulieWrites2