Thesis defense Ting Li (Donders series 474)
28 January 2021
Promotor: prof. dr. B. Franke
Co-promotors: de. A. Arias Vasquez, dr. N. Roth Mota, dr. D. van Nooij
Heterogeneity in neurodevelopmental disorders
Neurodevelopmental disorders (NDD) are a group of disorders with impaired development of the brain and/or central nervous system, which often lead to lifelong abnormal brain functioning. Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorders (ASD) are among the most common childhood-onset NDD. Two types of evidence about the nature of ADHD and ASD formed the starting points for this thesis. First, as a disorder, ADHD and ASD are at the extreme end of a trait distribution that extends throughout the general population. ADHD-related traits (ADHD symptomatology) and autistic traits are common in the general population. Second, both ADHD and ASD are heterogenous with regard to etiology, clinical phenotypes and psychiatric comorbidities, the developmental trajectories, and the associated structural and functional brain alterations. The aim of the research projects in the thesis was to gain further insight in the ADHD symptomatology in the general population, and disentangle the neuroanatomical heterogeneity of ADHD and ASD. We found ADHD symptomatology in the general population behave similar as the clinical extreme of the continuum, regarding to the developmental trajectory of ADHD symptoms, the comorbidity profile and the interplay of genetic and environmental risk factors for ADHD. Moreover, we found that more homogeneous subgroups with similar subcortical pattern exist in the population, irrespective of ADHD/ASD diagnosis. The stratification enhanced our ability to observe case-control differences of subcortical brain volumes in both ADHD and ASD.