According to a recent study, the number of children diagnosed with attention deficit hyperactivity disorder in the US increased by 42% between 2003-04 and 2011-12. The increase sparked concern that many children are being incorrectly diagnosed with the condition. But a new study published in the journal Radiology details a biomarker of ADHD that is identified through a brain imaging technique, which researchers say could help prevent misdiagnosis.

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that causes concentration problems, uncontrollable behavior and overactivity. ADHD onset usually occurs in childhood and the condition can last well into adulthood.

According to the research team, including Dr. Vitria Adisetiyo, postdoctoral research fellow at the Medical University of South Carolina, there has been much worry over the increasing rates of ADHD diagnosis in the US, particularly since around two thirds of those diagnosed receive psychostimulants – such as Ritalin – to help treat their condition.

Psychostimulants work to regulate impulsive behavior and improve attention span. But the medication also increases the levels of dopamine in the brain – a neurotransmitter linked to addiction – which may increase the likelihood of drug abuse.

In this latest study, the researchers set out to find a way to help prevent incidence of ADHD misdiagnosis, so children and adolescents are not subject to psychostimulant medication if it is not needed.

The team wanted to see whether levels of iron in the brain could be a potential biomarker for the diagnosis of ADHD.

In 2006, study co-authors Joseph Helpern, PhD, and Jens Jensen created a magnetic resonance imaging (MRI) technique – called magnetic field correlation imaging.

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Through magnetic field correlation imaging, researchers found that ADHD patients without a history of psychostimulant use had low brain iron levels, which may be a biomarker.
Image credit: Radiological Society of North America

Using this technique, the researchers measured the brain iron levels of 22 children and adolescents with ADHD, alongside 27 children and adolescents without the condition. Of participants with ADHD, 12 had never received psychostimulant medication for their condition. Participants’ iron levels in their blood were also measured.

The study results revealed that the 12 patients with ADHD who did not have a history of psychostimulant medication had much lower brain iron levels, compared with the remaining ADHD patients who had used psychostimulants and the healthy children and adolescents.

In fact, the team found that ADHD patients who had a history of psychostimulants had similar brain iron levels to the healthy patients, indicating that psychostimulant medication may normalize brain iron levels.

“Our research suggests that iron absorption into the brain may be abnormal in ADHD given that atypical brain iron levels are found even when blood iron levels in the body are normal,” explains Dr. Adisetiyo. “We found no differences in blood iron measures between controls, medication-naive ADHD patients or pscyhostimulant-medicated ADHD patients.”

Dr. Adisetiyo notes that at present, ADHD diagnosis relies on the patient taking part in subjective clinical interviews and questionnaires. But the team says their magnetic field correlation imaging technique could be used to improve ADHD diagnosis and treatment, as it can detect low iron levels in the brain.

They note that if their findings are duplicated in larger studies, the imaging technique could be used to identify the patients who would benefit from psychostimulant medication, while preventing others from being subject to the drugs if they are not needed.

Dr. Adisetiyo adds:

We want the public to know that progress is being made in identifying potential noninvasive biological biomarkers of ADHD, which may help to prevent misdiagnosis. We are currently testing our findings in a larger cohort to confirm that measuring brain iron levels in ADHD is indeed a reliable and clinically feasible biomarker.”

Medical News Today recently reported on a study, also published in the journal Radiology, which suggests that a resting-state functional magnetic resonance imaging (rfMRI) technique may provide accurate and early ADHD diagnosis.