Structual and neurochemical correlates of Tourette’s disorder and attention-deficit hyperactivity disorder

Structual and neurochemical correlates of  Tourette’s disorder and attention-deficit hyperactivity disorder

Tourette’s Disorder (TS) and attention-deficit/hyperactivity disorder (ADHD) are common childhood onset disorders that commonly occur together. What areas of the brain are involved in these disorders is still unclear but a set of brain networks connecting certain cortical and subcortical regions is thought to be involved in both, namely the cortico-striatal-thalamo-cortical (CSTC) networks. This thesis set out to determine the unique and common neurobiology of the disorders and focused on the neuroanatomy and neurochemistry of these networks.

We examined magnetic resonance imaging scans from children between 8 and 12 years old with TS and/or ADHD and healthy comparison children.

We found that the structure of the networks did not relate to either disorder. Similarly, the concentration of glutamate, the most important excitatory neurochemical in the brain, did not differ with diagnosis in the regions investigated. In one region, involved in cognitive control, attention and emotion regulation, we found obsessive-compulsive symptoms within participants with TS was related to the level of glutamate present. Autism symptom severity across all participants was found to relate to measures of cell density in the same region.

This work does not support CSTC involvement in TS and/or ADHD in children. Differences seen in adults may represent compensatory mechanisms. Results regarding obsessive compulsive behaviours and autism symptom severity require further investigation but are promising for the identification of neural correlates of autism symptoms and obsessive-compulsive traits in children.

Dissertation: http://hdl.handle.net/11370/ce207735-1a72-420c-821e-44fc57ee6573