Introduction
The first medical device to assist in the diagnosis of attention-deficit/hyperactivity disorder (ADHD) received US Food and Drug Administration (FDA) approval on July 15, 2013, and open comments on an American Academy of Neurology (AAN) Clinical Guideline for assessing the utility of this device recently closed.
The Neuropsychiatric EEG-Based Assessment Aid (NEBA) system measures the theta/beta ratio at Cz (vertex on the International 10-20 system) and was evaluated in two Class I clinical trials. It is not intended to diagnose ADHD independently but rather to "help clinicians more accurately diagnosis (sic) ADHD..." Patients are to be tested off medications. The device is manufactured by NEBA Health of Augusta, Georgia. The website advertises that clinics can rent the NEBA unit "starting at $79/month."
Discussion
I remember being astonished when this device received FDA approval last year. It presumes that consistent and reproducible EEG abnormalities exist in ADHD.
Increased EEG power in the theta band at rest has been observed as a possible biomarker for ADHD.[1] Until now, this observation has not been used for the clinical diagnosis of ADHD.
As the guideline points out, several EEG normal variants could affect theta power at Cz, such as the Ciganek rhythm, rhythmical mid-temporal theta, wickets, and mu. Not to overlook the obvious, the clinical state of drowsiness brings with it excessive theta that could possibly result in a positive test. Sleep problems are commonly reported in children and adolescents with ADHD.[2]
EEG abnormalities, such as rolandic spikes, have been observed to be increased in children with ADHD.[3] However, the underlying basis for the increase in these spikes and their relationship to ADHD symptoms remains to be clarified.
The FDA validation study states that the NEBA device should not be used in individuals with a history of EEG abnormalities, seizure disorder, on anticonvulsants, or with a metal plate or device in the head. Only "medical professionals qualified to assess psychiatric disorders and experienced in diagnosing ADHD" should employ the device.
It is critical to learn whether children and adolescents with ADHD have underlying neurophysiologic abnormalities that are responsible for their attention-deficit/hyperactivity behavior that can be reliably detected by EEG. If this is the case, then ADHD may be more of an "organic" than "environmental" disorder. One must question the origin of these neurophysiologic abnormalities and why they would affect such a large (and growing) percentage of the population.
The implications of an ADHD diagnosis are consequential, as many of these children and adolescents receive medication that may or may not improve their symptoms but certainly exposes them to the risk for adverse events.
One must also know the differential diagnosis of an abnormal NEBA result. For example, could an increase in theta/beta frequencies at Cz be due to anxiety, depression, a primary sleep disorder, or medication treatment?
The upcoming publication of the AAN guideline provides an opportunity to address multiple clinical questions regarding the use of EEG to help diagnose ADHD:
Does the NEBA test increase the accuracy of clinical diagnosis of ADHD? (If not, what is its value?)
If the NEBA test does work, which clinicians should administer it? Is training in EEG interpretation needed? (On the basis of the NEBA website, it appears that the results are interpreted offsite by the company.)
What is the likelihood that an abnormal result (increased theta/beta ratio at Cz) is due to normal variants and drowsiness?
What is the differential diagnosis of an abnormal NEBA result?
If brain waves are abnormal in ADHD, what is the underlying pathophysiology that creates this condition?
The conclusions of this AAN guideline will affect many children and adolescents with ADHD and those suspected of having this diagnosis. I submitted a comment, as I felt that the guidelines could be more clear on whether the new NEBA test should be used, and if so, when.
Medscape Neurology © 2014 WebMD, LLC
Cite this: Andrew N. Wilner. EEG for the Diagnosis of ADHD? - Medscape - Aug 28, 2014.
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