Autism, ADHD and OCD are neurodevelopmental disorders that together affect around 15 per cent of the youth population. Although they have traditionally been studied as separate disorders, they do have common symptoms as well as some genetic links with each other. A newly published MRI study shows they actually share brain biology characteristics and may lead to a new perspective on how and why these neurological conditions develop in childhood.

A team of Toronto scientists from three hospitals performed brain imaging of white matter in 200 children diagnosed with one of the three conditions, but were otherwise healthy. White matter is made up of nerve fibers that enable communication between different regions of the brain. In children with autism, ADHD and OCD they found impairments in white matter in the main tract connecting the right and left hemispheres of the brain. Known as the corpus callosum, it is the largest white matter tract in the brain, critical for allowing neural communication between each side of the brain.

The finding of this study is significant because it provides biological evidence that impairments in actual brain structure relate to a spectrum of behavioural symptoms across different developmental conditions. This suggests potential for new forms of treatments targeting a spectrum of behaviours rather than isolated conditions. As there was also correlational evidence that the progression of symptoms is related to the development of white matter tracts at a young age, it may also pave the way for early intervention reducing the lifelong onset of symptoms.

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A Diffusion Tensor Imaging Study in Children with ADHD, Autism Spectrum Disorder, OCD and Matched Controls: Distinct and Non-Distinct White Matter Disruption and Dimensional Brain-Behaviour Relationships.

American Journal of Psychiatry, 2016

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