Thesis defense Christienne Gonzales Damatac (Donders series 592)

25 January 2023

Promotor: prof. dr. C.F. Beckmann
Co-promoter: dr. E. Sprooten

White matter microstructural development in the course of ADHD

Though attention-deficit/hyperactivity disorder (ADHD) is the world’s most common neurodevelopmental disorder, much remains unknown about what determines the onset or progression of its symptoms. The process of neurodevelopment includes the maturation of neurons and white matter, which provides structural organization for the brain. Neuroscientists have used white matter as an indicator for the level of communication between brain areas. The work undertaken in this thesis aimed at discovering how the development of ADHD relates to white matter in the brain as a person grows up from adolescence to adulthood. We analyzed diffusion magnetic resonance brain images collected at three times over about seventeen years. We used different types of techniques and statistical modeling to systematically assess whether there were differences in the brains of people with and without ADHD throughout time.

We found changes in white matter that occurred in specific brain areas and were related to symptom severity. Our results also tell us that the parts of the brain that play a role in disorder onset are different from those that are important for remission. Additionally, when compared with those whose symptoms remit over time, people with persistent ADHD symptoms seemed to have different white matter developmental trajectories. Notably, different outcomes of white matter development might be moderated by earlier symptom trajectories. We propose that the longitudinal course of symptoms in ADHD precedes or partly determines the developmental trajectories of white matter in specific fiber tracts. Future research in ADHD can thus focus on uncovering remission-specific brain areas or networks, potentially producing new and more effective clinical strategies.