Meta-analysis of structural MRI studies in children and adults with attention deficit hyperactivity disorder indicates treatment effects.
About 50-80% of ADHD cases have been found to persist into adulthood, but ADHD symptoms change with age. The aim of this study was to perform a meta-analysis of MRI voxel-based morphometry (VBM) and manual tracing studies to identify the differences between adults and children with ADHD as well as between treated and untreated individuals. Several databases were searched using keywords 'attention-deficit and MRI', 'ADHD and MRI'. Gray matter volumes from VBM studies and caudate volumes from tracing studies of patients and controls were analyzed using signed differential mapping. Meta-analyses detected reduced right globus pallidus and putamen volumes in VBM studies as well as decreased caudate volumes in manual tracing studies in children with ADHD. Adult patients with ADHD showed volume reduction in the anterior cingulate cortex (ACC). A higher percentage of treated participants were associated with less changes. Basal ganglia regions like the right globus pallidus, the right putamen, and the nucleus caudatus are structurally affected in children with ADHD. These changes and alterations in limbic regions like ACC and amygdala are more pronounced in non-treated populations and seem to diminish over time from child to adulthood. Treatment seems to have positive effects on brain structure. © 2011 John Wiley & Sons A/S.