Attention-deficit hyperactivity disorder (ADHD) -- one of the most misdiagnosed conditions that leads to many children taking Ritalin (methylphenidate) even though they don't need it -- can now be identified objectively and in a foolproof way.
Researchers at Tel Aviv University's Sackler Faculty of Medicine and colleagues at Sheba Medical Center and the University of Haifa have found that involuntary eye movements accurately reflect the presence of ADHD.
Until this discovery, there had been no reliable physiological markers to diagnose ADHD. Parents brought in their children asking for a prescription for Ritalin, which in some cases improves concentration and class performance and grades even in children who do not suffer from ADHD.
Doctors generally diagnose the disorder by recording a medical and social history of the patient and the family, discussing possible symptoms and observing the patient's behavior. As a result, too many children get the drug, and there is even illegal trade in prescriptions. An incorrect evaluation can lead to overmedication with Ritalin, which has doctors, pharmacists and parents concerned.
A report on the objective tool to accurately diagnose ADHD has just been published in the journal Vision Research.
Dr. Moshe Fried, Dr. Anna Sterkin and Prof. Uri Polat of TAU; Dr. Tamara Wygnanski-Jaffe, Dr. Eteri Tsitsiashvili, Dr. Tamir Epstein of Sheba's Goldschleger Eye Research Institute; and Dr. Yoram S. Bonneh of Haifa developed the eye-tracking system. They studied two groups of 22 adults to monitor their involuntary eye movements and gave them an ADHD diagnostic computer test called the Test of Variables of Attention (TOVA). The exercise, which lasted 22 minutes, was repeated twice by each participant. The first group of participants, diagnosed with ADHD, initially took the test unmedicated and then took it again under the influence of Ritalin. A second group, not diagnosed with ADHD, constituted the control group.
"We had two objectives going into this research," said Fried, who as an adult was himself diagnosed with ADHD. "The first was to provide a new diagnostic tool for ADHD, and the second was to test whether ADHD medication really works. We found that it does. There was a significant difference between the two groups, and between the two sets of tests taken by ADHD participants unmedicated and later medicated."
The researchers found a direct correlation between ADHD and the inability to suppress eye movement in the anticipation of visual stimuli. The research also reflected improved performance by participants taking methylphenidate, which normalized the suppression of involuntary eye movements to the average level of the control group.
"This test is affordable and accessible, rendering it a practical and foolproof tool for medical professionals," said Fried. "With other tests, you can slip up, make 'mistakes' – intentionally or not. But our test cannot be fooled. Eye movements tracked in this test are involuntary, so they constitute a sound physiological marker of ADHD. Our study also reflected that methylphenidate does work. It is certainly not a placebo, as some have suggested."
The researchers are currently conducting more extensive trials on larger control groups to further explore applications of the test.
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