In a study published yesterday in the New England Journal of Medicine, scientists from the University of California San Diego (UCSD) and the Allen Institute for Brain Science present findings which suggest that defects in the formation of particular areas of the brain in autistic individuals begins long before birth.
Autism is one of the three disorders recognized under the umbrella term Autism Spectrum, and is a neural development disorder. Individuals with autism typically show impaired social interaction and communication and often display certain characteristic behaviors. Although some information is known about the brains of autistic individuals, when and how autism develops was previously poorly understood. This new study has evidence to strongly suggest that it begins in the womb.
The scientists analyzed post-mortem brains of 22 children with and without autism, between the ages of 2 and 15. They investigated 25 different genes; some of which were genetic markers for cells in different cortex layers, others had been implicated in autism, and some were control genes. During pregnancy the cortex of the brain develops multiple layers; the different cell types found in these 6 distinct layers perform unique roles in information processing, and possess specific genetic markers. The scientists found that the majority of the autistic brains had localized patches of disrupted development in these cortical layers. Professor of neuroscience at UCSD Eric Courchesne said "This defect indicates that the crucial early developmental step of creating six distinct layers with specific types of brain cells- something that begins in prenatal life- had been disrupted." Not only that, but they found that certain specific markers were absent in cells of multiple different layers of the cortex.
Patches of the cortex which seemed to be most affected by this absence of genetic markers were those known to be involved in social communication and language, which are impaired in autistic individuals. The finding that it is not the entire cortex that is affected, but instead specific localized patches, gives both hope and insight into the nature of autism, according to Courchesne. It may also help to explain why some young children improve with early treatment, as the brain seems to be capable of compensatory re-wiring. It is hoped that this information may eventually shed light on the mechanisms underlying this improvement.
Director of the National Institute of Mental Health Dr Thomas Insel told the BBC "If this new report of disorganized architecture in the brains of some children with autism is replicated, we can presume this reflects a process occurring long before birth. This reinforces the importance of early identification and intervention." It is hoped that this increase in understanding of brain development may eventually lead to an improvement of the lives of children with autism.