1. ¹Academic Child Psychiatry Unit, Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Murdoch Children's Research Institute, Parkville, VIC, Australia
2. ²School of Psychology, Psychiatry and Psychological Medicine, Monash University, Clayton, VIC, Australia
3. ³School of Behavioural Science, University of Melbourne, Parkville, VIC, Australia
4. ⁴Howard Florey Institute and Centre for Neuroscience, University of Melbourne, Parkville, VIC, Australia

Correspondence: Professor A Vance, Academic Child Psychiatry Unit, Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Parkville, VIC 3052, Australia. E-mail: avance@unimelb.edu.au

Received 4 October 2006; Revised 8 February 2007; Accepted 8 February 2007; Published online 1 May 2007.

Abstract

Attention deficit hyperactivity disorder, combined type (ADHD-CT) is associated with spatial working memory deficits. These deficits are known to be subserved by dysfunction of neural circuits involving right prefrontal, striatal and parietal brain regions. This study determines whether decreased right prefrontal, striatal and parietal activation with a mental rotation task shown in adolescents with ADHD-CT is also evident in children with ADHD-CT. A cross-sectional study of 12 pre-pubertal, right-handed, 8–12-year-old boys with ADHD-CT and 12 pre-pubertal, right-handed, performance IQ-matched, 8–12-year-old healthy boys, recruited from local primary schools, was completed. Participants underwent functional magnetic resonance imaging while performing a mental rotation task that requires spatial working memory. The two groups did not differ in their accuracy or response times for the mental rotation task. The ADHD-CT group showed significantly less activation in right parieto-occipital areas (cuneus and precuneus, BA 19), the right inferior parietal lobe (BA 40) and the right caudate nucleus. Our findings with a child cohort confirm previous reports of right striatal-parietal dysfunction in adolescents with ADHD-CT. This dysfunction suggests a widespread maturational deficit that may be developmental stage independent.