Fronto-striatal underactivation during interference inhibition and attention allocation in grown up children with attention deficit/hyperactivity disorder and persistent symptoms

Attention deficit hyperactivity disorder (ADHD) in medication-naive children has been associated with reduced activation in inferior/medial prefrontal, striatal and parieto-temporal cortices during inhibitory control and attention allocation. Functional magnetic resonance imaging (fMRI) studies in adult ADHD, however, have been inconsistent and confounded by medication-history and the need for a retrospective diagnosis of childhood ADHD. We used fMRI combined with a Simon task that measured interference inhibition and controlled for and co-measured attention allocation to compare brain function in 11 medication-naive adults with persistent inattentive/hyperactive behaviours, followed up from childhood ADHD, and 15 age-matched controls. Despite comparable task performance, patients showed reduced activation compared to controls in left orbital/medial frontal cortex and striatum during interference inhibition and in left lateral inferior/dorsolateral prefrontal cortex during attention allocation. Whole-brain regression analyses within patients showed a negative correlation between symptom severity and fronto-striatal, temporo-parietal and cerebellar brain activation. The findings demonstrate that the typical fronto-striatal dysfunction observed in children with ADHD during interference inhibition and attention allocation is also observed in adults grown up from childhood ADHD with persistent symptoms. Furthermore, they show that functional deficits in adult ADHD are not related to chronic stimulant medication given that this sample was medication-naive. (C) 2011 Elsevier Ireland Ltd. All rights reserved.