August 20, 2014
- Eye May Be Key to More Accurate ADHD Diagnosis
A simple test examining involuntary eye movements may provide an objective
way to tell whether individuals have attention-deficit/hyperactive disorder
(ADHD) and whether stimulant medication will be an effective treatment, new
Investigators from Tel Aviv University in Tel Hashomer, Israel, observed
increased microsaccades and blink rates in adults with ADHD, which
normalized with methylphenidate treatment.
“We had 2 objectives going into this research,” lead investigator Moshe
Fried, PhD, from the Goldschleger Eye Institute, said in a statement. “The
first was to provide a new diagnostic tool for ADHD, and the second was to
test whether ADHD medication really works — and we found that it does. It
is certainly not a placebo, as some have suggested.”
The study was published
<http://www.sciencedirect.com/science/article/pii/S0042698914001187> in the
August issue of *Vision Research.*
*“Striking” Predictive Effect*
“The rationale behind our study was following recent studies ― of ours and
others ― which found that the rate of microsaccades is inversely correlated
with the level of attention,” Dr. Fried told *Medscape Medical News.*
In this latest study, the investigators recorded involuntary eye movements
in 22 adults with ADHD with and without methylphenidate and 22 control
individuals while they performed the test of variables of attention (TOVA).
They found that unmedicated ADHD patients had significantly higher rates of
eye blinks and microsaccades compared with control participants. This
effect was largest in the peristimulus period, “where eye movements should
be suppressed because they could interfere with the task,” the researchers
In addition, stimulant medication had a “striking effect” on involuntary
eye movements, with full normalization of the microsaccade rate to the
control level and partial normalization of blink rates, mainly in the
peristimulus interval, they report.
“In order to develop a clinical differential diagnostic tool, a more
refined study should be conducted,” said Dr. Fried. “Specifically, patients
should be divided into subtypes ― for example, ‘inattentive’ vs ‘impulsive’
― and also the control group should be screened to exclude potentially
undiagnosed ADHD subjects.”
*“Promising” Diagnostic Tool*
“This is an interesting paper,” Emanuel Bubl, MD, from Albert-Ludwigs
University of Freiburg, Germany, told *Medscape Medical News.*
“The study has many strengths, starting with an easy approach to the
patient by investigating the visual system and documenting a normalization
after therapy,” Dr. Bubl commented.
“The results are in line with findings from animal research and human
studies where methylphenidate acts by stabilizing neuronal networks and
reducing background noise. The authors link their finding to the arousal
system, and there is good evidence that especially the dopamine system with
the dopamine-1 receptor plays a prominent role in ADHD,” he added.
“In my opinion, a diagnostic strategy, accessing the eye to find a
diagnostic tool, has a lot of potential to reach clinic and is a promising
tool for the future,” Dr. Bubl said.
In his own research, Dr. Bubl has found that examining the retina may aid
in the diagnosis of ADHD. As reported
<http://www.medscape.com/viewarticle/804409> by *Medscape Medidcal News*,
in a small study, he and his colleagues showed that patients with ADHD
displayed significantly elevated “background noise” on pattern
electroretinography compared with their healthy peers.
*The study was supported by the National Institute for Psychobiology in
Israel, the Charles E. Smith family, and the Israel Science Foundation. The
authors report no relevant financial relationships.*
*Vision Res.* 2014;101:62-72. Abstract
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