Megan Brooks

May 18, 2013

SAN FRANCISCO — Examining the retina may aid in the diagnosis of attention-deficit/hyperactivity disorder (ADHD), new research suggests.

A small study by investigators at Albert-Ludwigs University of Freiburg, Germany, showed that patients with ADHD displayed significantly elevated "background noise" on a pattern electroretinogram (PERG) compared with their healthy peers.

Altered visual signal processing may be a "neuronal correlate for ADHD," study presenter Emanuel Bubl, MD, told Medscape Medical News. "If we can replicate this finding, it would be of great clinical importance because it would be an objective marker of ADHD."

Dr. Bubl presented the study here at the American Psychiatric Association's 2013 Annual Meeting.

PERG — which is a kin to an electrocardiogram of the retina — provides an electrophysiologic measurement of the activity of the retinal ganglion cells.

"This technique is an easy-to-apply and already well-established instrument in ophthalmology. With adaption, it could be widely used," Dr. Bubl said.

Inattention and distractability are core symptoms of ADHD, but a "clearcut neuronal correlate is missing. Any attempt to find objective markers of ADHD would be very helpful in this context," Dr. Bubl said.

Dr. Bubl and colleagues used PERG to measure the response of the retina to a checkerboard visual stimuli in 20 patients with ADHD and 20 healthy control participants.

"An elevated neuronal noise or background firing has been proposed as an underlining pathophysiological mechanism and treatment target. We found evidence for an early alteration in visual perception or signal transmission in patients with ADHD, with significantly elevated neuronal noise (P < .014)," said Dr. Bubl. In particular, neuronal noise significantly correlated with inattention, as measured with the Conners' Adult ADHD Rating Scale.

"The results might explain why patients with ADHD are easily distracted," Dr. Bubl added.

With more study, the results could have potentially important clinical implications. "With ADHD, there is a debate about the existence of the disease on the one hand and a growing concern about overdiagnosing ADHD and prescription of medication on the other," he said.

With PERG, the diagnosis of ADHD could be "objectified by measurable signals, and this would be dramatically helpful in the controversial public discussion." Use of PERG might also help in determining the effects of methylphenidate or psychotherapy on ADHD.

The authors report no relevant financial relationships.

The American Psychiatric Association's 2013 Annual Meeting. Abstract SCR02-2. Presented May 18, 2013.


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