Subgroup (image) Radiological Society of North America Caption This shows subgroup averages of parametric maps of MRI brain iron indices: magnetic field correlation (MFC: top row) and relaxation rates R2 (second row), R2*(third row), and R2' (bottom row). Parametric maps, masked for regions of interests (green): caudate nucleus (CN), putamen (PUT), globus pallidus (GP) and thalamus (THL), are shown for controls (n = 27), medication-naïve ADHD patients (ADHD-non-medicated; n = 12) and ADHD patients with a history of psychostimulant treatment (ADHD-medicated; n = 10). The ADHD-non-medicated subgroup displayed significantly reduced striatal (CN, PUT) and thalamic MFC compared to both controls and the ADHD-medicated subgroup. No significant differences were detected between the latter two groups. Credit Radiological Society of North America Usage Restrictions May use with credit Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.