Thesis defense Marten Onnink (Donders series 228)

9 June 2016

Promotors: prof. dr. J. K. Buitelaar, prof. dr. B. Franke
Copromotors: dr. M. Hoogman, dr. M. Zwiers

Understanding adult ADHD From genes to brain to behavior

ADHD is a neurodevelopmental disorder, which is highly heritable and in many cases affects an individual from childhood to adulthood. However, research on adults with ADHD continues to lag behind that on children with ADHD, in number and sample size. For a better understanding of adult ADHD, Marten Onnink investigated in a large group of adult ADHD patients the cognitive performance and he looked at brain structure using MRI. Results showed that adult patients with ADHD, as a group, present similar neuropsychological performance characteristics as reported for childhood ADHD such as attention and working memory. Similar to childhood ADHD, adult ADHD is neuropsychologically heterogeneous, with different patients affected to a different degree and some patients not showing neuropsychological deficits at all. When looking at the brain, it seems that adult patients do not show a reduction in total brain volume compared to controls, although there were differences in white matter, or the brain’s wiring. Marten Onnink found that the structural integrity of the white matter tracts is lower in adult ADHD patients and this seems to be due to aberrant myelination. Myelin protects and insulates neurons and affects information processing and cognition and might be a potential target for new therapeutic interventions.