Symptoms and structures: MRI sees brain changes

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  • Published: Aug 1, 2016
  • Author: David Bradley
  • Channels: MRI Spectroscopy
thumbnail image: Symptoms and structures: MRI sees brain changes

ASD, ADHD, OSD

Stephanie Ameis and colleagues have found that MRI can reveal differences in brain structure that are common to autism, ADHD and OCD. Credit: Centre for Addiction and Mental Health (CAMH)

Magnetic resonance imaging (MRI) reveals differences in brain structure common to disparate conditions in children including autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD) and obsessive compulsive disorder (OCD).

Stephanie Ameis, a clinician-scientist at the Centre for Addiction and Mental Health (CAMH’s) Campbell Family Mental Health Research Institute in Toronto, Canada, and her colleagues explain that neurodevelopmental disorders such as ASD, ADHD, and OCD share several genetic vulnerabilities as well as having overlapping symptom domains. In order to understand the links at the neurological level, the researchers have used MRI to make a direct comparison of the structural brain circuitry in children and adolescents with such disorders and to compare the data with control subjects.

They investigated diffusion imaging and behavioural measures for 200 children and adolescents of average age between 10 and 13 years old who had one or more of the aforementioned conditions. They looked at the Tract-Based Spatial Statistics in a multigroup comparison of white matter indices and then made pairwise comparisons. They then determined whether or not there was a link with inattention, social deficits, OCD symptoms, and general adaptive functioning in the non-control group. The team reports details in the American Journal of Psychiatry.

Other side of the tracts

The team found that the structure of white matter was associated with a spectrum of behavioural symptoms present in these disorders. Children with greater brain impairment also had higher impairments in functioning in daily life, regardless of their diagnosis, says Ameis.

"We found impairments in white matter in the main tract connecting the right and left hemispheres of the brain in children with either autism, ADHD or OCD, when compared to healthy children in the control group," explains Ameis. White matter in the brain is involved in communication between different regions, in contrast to so-called grey matter which is associated with processing. The corpus callosum is the largest white matter tract in the brain and among the first to develop. In addition to those differences, the team also found that there were more severe impairments affecting more of the white matter in children with ASD or ADHD than in those with OCD. This discovery might be explained by the fact that both autism and ADHD commonly emerge in much younger children than those who develop OCD. In younger children a number of different white matter tracts are undergoing rapid development at the same time adds Ameis.

Development

Scientists already knew that ASD, ADHD and OCD share many of their symptoms and apparently are associated with several of the same genes. However, researchers have tended to view them entirely separate disorders and to, historically at least, study them separately. However, as whole these three neurodevelopmental disorders affect about 15 per cent of children and youths. Much of the behaviour considered impairment in ASD, ADHD, and OCD, including problems of concentration and attention and social difficulties, occur across all three conditions but differ in their severity and impact from person to person.

In the present study, which is part of an ongoing initiative, the Province of Ontario Neurodevelopmental Disorders Network (POND), the overall aim is to examine all of these various childhood brain-related disorders together so that a better understanding of their similarities and differences might emerge and lead to a new and more effective approach to targeted therapies.

The results highlight the shared brain biology of these disorders and have implications for understanding and treatment, Evdokia Anagnostou of Holland Bloorview Rehabilitation Hospital and head of the POND Network suggests.

"We are hoping that we might be able to study whether treatments that may be able to improve everyday functioning could have utility across children with autism, ADHD and OCD and have an effect on brain wiring," Ameis told SpectroscopyNOW. "Currently, we diagnose autism, OCD, and ADHD based on the presence of particular clinical symptoms. We are not at the point yet where we are able to use something like brain imaging in the clinical setting to better understand the specific biology underlying a child's particular difficulties nor can we use that type of information to guide treatment." She adds that the present work might provide a clue to eventually provide a clinical diagnosis to a child. Then using brain imaging it might be possible "to examine what the particular changes in brain wiring are for that child and based on that information suggest a specific treatment pathway that we know can positively target that wiring and help with symptoms, behaviour and functioning."

Related Links

Am J Psychiatr, 2016, online: "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-Behavior Relationships"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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