Browsing by Subject "koko aivojen konnektiivisuus"

Objectives. ADHD (attention deficit/hyperactivity disorder) is a neurodevelopmental disorder characterised by inattention, hyperactivity and impulsivity. In majority of the cases, these symptoms persist into adulthood, but research from adult ADHD is lacking despite the many negative impacts it has on everyday life. Nowadays ADHD symptoms are seen to arise from structural and functional changes in multiple brain networks. Structural connectivity between brain regions also forms a basis for their functional co-operation. Studying structural connectivity is therefore essential for understanding the neural basis of adult ADHD. The aim of this thesis was to study the complex structural connectivity changes in adults with ADHD. Connectivity was studied exploratively by using a whole-brain approach and in addition in two networks often related to ADHD, dorsal attention network (DAN) and default mode network (DMN). Methods. Structural brain connectivity was measured with diffusion weighted magnetic resonance imaging and connectivity strength was compared between adults with ADHD (n = 39) and healthy controls (n = 18). Whole-brain connectivity was studied with Network-based statistics to find networks that differed in structural connectivity between groups. In addition, structural connectivity within and between DAN and DMN was compared between groups. We also studied how connectivity strength in the networks was related to ADHD symptoms and to performance in a continuous performance test. Results and conclusions. Adults with ADHD had almost statistically significant decreased structural connectivity in two large-scale networks connecting multiple lateral and medial cerebral brain regions and cerebellum. In addition, the ADHD group had decreased structural connectivity in the left-sided DAN. Decreased connectivity was associated with more ADHD symptoms and worse performance in the continuous performance test. Most of the connections distinguishing ADHD participants from healthy controls in the whole-brain analysis were between different brain networks, not within these networks. These networks included the frontoparietal, DMN, visual and somatomotor networks. Results suggest that whole-brain approaches can be used to study structural connectivity changes related to the symptoms and weaker task performance in adult ADHD.