MRI Detects Low Brain Iron Levels in Medication-Naive ADHD Patients

December 2, 2013

CHICAGO - Magnetic field correlation, a newer type of MRI, can detect low levels of iron in the brains of children and adolescents with ADHD who are ADHD medication-naive.

CHICAGO - Magnetic field correlation, a newer type of MRI, can detect low levels of iron in the brains of children and adolescents with ADHD who are ADHD medication-naive.

Magnetic resonance imaging detects lower brain iron levels in people with attention deficit hyperactivity disorder (ADHD) who are ADHD medication-naïve and who appear to normalize with medication, according to a study presented at RSNA 2013.

While researchers suspect that dopamine levels are part of the ADHD pathology, both increased and decreased levels of dopamine have been detected in people with ADHD. However, it has been found that patients who are medication-naive have reduced dopamine markers and those who have taken medications for ADHD symptoms have higher levels of dopamine.

Researchers from the Medical University of South Carolina in Charleston, S.C., assessed the relationship between medication history and brain iron levels in children and adolescents with ADHD by measuring iron levels. Brain iron is required for dopamine synthesis. By measuring iron levels, the researchers hoped that measurement by MRI would provide a noninvasive, indirect measure of dopamine.

Twenty-two subjects with ADHD (12 medication-naïve and 10 who took ADHD medications) and 27 healthy controls were recruited into the trial. All underwent an MRI technique called magnetic field correlation (MFC) imaging.

"MRI relaxation rates are the more conventional way to measure brain iron, but they are not very specific," Vitria Adisetiyo, PhD, said in a release. "We added MFC because it offers more refined specificity." Adisetiyo is a postdoctoral researcher fellow at the university.

The globus pallidus (GP), caudate nucleus (CN), putamen (PUT) and thalamus (THL) were chosen as regions of interest because of their suspected role in ADHD in addition to having high iron content. Serum iron measures were also collected.

The findings showed that the medication-naïve group had significantly lower magnetic field correlation (MFC) than both the medicated and control groups in three of the four brain regions studied. The lower brain iron levels in the non-medicated group appeared to normalize with psychostimulant medication.

MFC imaging's ability to noninvasively detect the low iron levels may help improve ADHD diagnosis and guide optimal treatment. Using such methods would allow clinicians who are uncertain of a diagnosis of ADHD to confirm low brain iron levels.

 

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Figure 1. Medication-naïve ADHD patients (ADHD-non-medicated) have reduced striatal (putamen (PUT), caudate nucleus (CN)) and thalamic (THL) magnetic field correlation (MFC) measures of brain iron compared to controls and psychostimulant medicated ADHD patients (ADHD-medicated); Brain iron measures in PUT, CN, THL or globus pallidus (GP) did not differ between controls and psychostimulant medicated ADHD patients. These statistical significant differences are visible in the MFC group maps (top row) but not in conventional relaxation rate maps: R2 (second row), R2*(third row), and R2' (bottom row).