Treatment appears to have a positive effect on ADHD brain structure, researchers in Ireland have found.

The findings were published online November 28 by researchers at the Department of Psychiatry, Trinity College Dublin, Dublin St. James’s, Adelaide and Meath Hospitals Incorporating the National Children’s Hospital, Psychiatric Services, Dublin Lindara Child and Adolescent Mental Health Service, Dublin, Ireland.

T. Frodl and N. Skokauskas performed a meta-analysis of MRI studies to determine the effects of treatment on brain structure in children and adults with ADHD. They hoped to identify differences between children and adults with ADHD, as well as the differences between individuals who were treated and untreated.

The researchers searched databases to find studies using MRS voxel-based morphometry (VBM) and manual tracing. Gray matter volumes from VBM studies and caudate volumes from tracing studies of patients and controls were analyzed using signed differential mapping.

In children with ADHD, VBM studies showed changes in the basal ganglia, such as reduced right globus pallidus and putamen volumes; manual tracing studies showed decreased caudate volumes. In adults with ADHD, the limbic region was affected, with a volume reduction in the anterior cingulate cortex (ACC).

A higher percentage of treated participants was associated with fewer changes.

“Alterations in limbic regions like ACC and amygdala are more pronounced in non-treated populations and seem to diminish over time from childhood to adulthood,” the researchers found.

“Treatment seems to have positive effects on brain structure,” they concluded in their abstract, published in the journal Acta Psychiatrica Scandinavica.

Frodl, T. and Skokauskas, N. (2011), Meta-analysis of structural MRI studies in children and adults with attention deficit hyperactivity disorder indicates treatment effects. Acta Psychiatrica Scandinavica. doi: 10.1111/j.1600-0447.2011.01786.x