[Neuroimaging data of ADHD, tic-disorder and obsessive-compulsive-disorder in children and adolescents]

ADHD, Tic Disorder, Tourette's Syndrome, and Obsessive-Compulsive Disorder are all characterised by an impairment of executive functioning and often occur together. There are thus indications of a similar neurobiological basis. This review presents an overview of neuroimaging studies of these disorders in childhood and adolescence, focusing thereby on magnet resonance imaging data. Studies provide concurring data about structural changes in the basal ganglia and the prefrontal cortex, and abnormal activation in the fronto-striatal circuitry in patients as compared to healthy controls. ADHD and Tourette's Syndrome are both associated with prefrontal aberrations. However, variances in Tourette's Syndrome are less pronounced, which might be due to compensation mechanisms. ADHD children show small, but more global, morphological alterations in the cortex and cerebellum, while Tourette's Syndrome seems to be linked additionally to differences in the occipital cortex. Furthermore, structural and functional data for obsessive-compulsive disorder indicate aberrations in the amygdala and thalamus, and functional changes in the orbito-frontal cortex. By comparison, findings in children with ADHD point towards abnormal activity in the ventral prefrontal cortex. To summarise, the data display an impairment of cortico-striato-thalamic circuits which appears to be associated with dysfunctioning motor inhibition, and impulsive behaviour and objectionable thoughts. Since the majority of the studies reviewed are characterised by small and heterogeneous samples, and since the studies differ in their methods, comparability is limited and general conclusions can not be drawn.