Eye movements could help diagnose ADHD
Researchers say involuntary eye movements are a reliable physiological marker for diagnosing the disorder.
Attention deficit hyperactivity disorder is one of the most commonly diagnosed – and misdiagnosed – disorders in children. With no reliable physiological marker to indicate it, an ADHD diagnosis is based on a patient's medical and social history. A new study, however, claims that a physiological marker does exist – and it's all in the eyes.
The research has found that involuntary eye movements could help doctors diagnosis the disorder more accurately – and that medications like Ritalin (methylphenidate) are effective in treating it.
In the study published in the journal Vision Research, scientists, led by Dr. Moshe Fried at Tel Aviv University's Sackler School of Medicine, used an eye-tracking system to monitor eye movements in two groups of 22 adults as they completed a computer-based Test of Variables of Attention – a common test for ADHD. The first group had been previously diagnosed with ADHD; the second was a control group of people who had not been diagnosed with the disorder. The ADHD-diagnosed group completed the test with and without medication. Results of the testing showed a direct correlation between involuntary eye movement and ADHD.
"We had two objectives going into this research. The first was to provide a new diagnostic tool for ADHD, and the second was to test whether ADHD medication really works." Dr. Moshe Fried
On average, the researchers found that small, involuntary jerk-like eye movements and blink rates were higher in the unmedicated ADHD group, especially in anticipation of visual stimuli. These rates increased at a corresponding rate throughout the session for both groups, but the unmedicated ADHD group increased at significantly faster increments. When medicated, the ADHD group's eye movements were normalized to the average level of the control group.
“We had two objectives going into this research,” said Fried. “The first was to provide a new diagnostic tool for ADHD, and the second was to test whether ADHD medication really works.”
Researchers say their findings suggest that ADHD subjects are unable to remain sufficiently alert and attentive during simple and prolonged tasks, and that medication helps those who need it.
Previous research has tested anticipatory body and eye movements in relation to ADHD and other psychological disorders, and one team even holds a U.S. patent for a method of diagnosing ADHD through “angular movements of the eyeball.” That study differs in one crucial respect from the Tel Aviv research: Eye movements were measured while subjects stared at a blank screen rather than while taking the TOVA test.
"The control of eye movements is foundational for everything an individual might do in life, and if compromised, it can lead to reduced ability and function," Dr. Dawn Stratton, founder of Stratton Eyes, based in Lexington, Ky., wrote in a recent article on KyForward. "Eye movements and control are among the foundational processes evaluated in every eye exam, particularly in all ages where attention issues may be present. I encourage parents of children with suspected attention disorders to have their children undergo a comprehensive eye examination by an optometrist in order to determine the extent that vision might play in the overall process."
Fried said this new test is affordable, accessible and more reliable than using patient history for diagnosing ADHD, making it more practical for medical professionals.
Research to explore further applications of the test is ongoing, Fried said.
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