EEG brainwave tests can diagnose ADHD, including sub-types
To date, there have been few reliable ways to confirm an attention-deficit/hyperactivity disorder (ADHD) diagnosis, but a new study recently found that using electroencephalogram (EEG) to test brainwaves may help diagnose two subtypes of the disorder known as "inattentive" or "combined" (the latter including both inattentiveness and hyperactivity).
Researchers involved in the study, which has been published in the journal Biological Psychiatry, say that the EEG test results demonstrate "that these groups display distinct physiological profiles."
In other words, EEG may be an effective and objective biological test for identifying specific sub-types of ADHD that can be subjectively observed in the clinic.
"This study shows that there are changes in brainwaves related to visual processing and motor planning that can be used to distinguish ADHD subtypes," says Ali Mazaheri, assistant professor University of Amsterdam in the Netherlands, and a guest researcher at the Center for Mind and Brain of the University of California, Davis.
He added that subtypes of ADHD “appear subjectively very different in the clinical setting, but there are few objective physiological markers that have been able to detect those differences."
For the study, which was conducted from 2009 to 2013, 17 children between the ages of 12 and 17, as well as 23 same-aged children without ADHD, wore EEG caps with 32 electrodes that the researchers used to assess how they performed a computer task.
The group of children and teens were given visual cues to help with their performance, with some cues being more obvious than others, and therefore not as helpful, so the test became more difficult for those with ADHD because responding correctly required them to override initial impulses.
In one task, for example, the child was asked to look at a series of arrows pointing in different directions on the computer screen, and to show which direction the center arrow was pointed in.
After the child viewed the visual cues, their alpha and beta brainwaves were read on EEG. As a result, the researchers saw differences between the children and teens who had either one of the two ADHD subtypes. The researchers could also tell which of the participants were developing normally and did not have ADHD.
"The alpha wave patterns of teens with the inattentive type of ADHD did not process the important information in the visual cues, limiting their ability to succeed," the researchers reported.
Those participants who had the most difficulty pressing a button also turned out to be the ones who had the combined-type of ADHD, as indicated by measurements of beta wave patterns that helped monitor motor task performance.
The study’s findings are most remarkable for challenging the notion that combined-type ADHD is worse than the inattentive type. According to the researchers, it instead appears to be a different type of ADHD – and not a type that involves a combination of symptoms, which may help when it comes to prescribing more sensitive treatments.
"This research also gives us clues regarding the development of treatments to address the underlying processing differences between ADHD subtypes,” said co-author Catherine Fassbender, a research scientist with the MIND Institute at UC Davis. “Most treatments for ADHD do not take subtype differences into account," Fassbender added.
"Our findings suggest targets for treatment should differ for the ADHD inattentive versus combined subtypes, and that advanced analysis of brainwaves may provide a biomarker for testing treatment responses," she concludes.
In another recent study, researchers discovered that combining EEG feedback with drug treatment improved outcomes for those with ADHD, with EEG feedback by itself having an rate of effectiveness "as high as 60-70%", and "results in long-term steady improvement on emotional, behavioral and academic performance, as well as improved cognition and performance in daily activities." The study involved a randomized trial of EEG feedback in combination with the commonly used ADHD stimulant medication, Ritalin (methylphenidate).
SOURCES: 1.) Differential oscillatory electroencephalogram between attention-deficit/hyperactivity disorder subtypes and typically developing adolescents, Mazaheriemail A, Fassbender C, Coffey-Corina S et al., Biological Psychiatry, published online October 11, 2013 (DOI: 10.1016/j.biopsych.2013.08.023). 2.) A randomised controlled trial of combined EEG feedback and methylphenidate therapy for the treatment of ADHD, Lia L, Yanga L, Zhuoa C and Wanga YF, Swiss Medical Weekly, published online August 22, 2013 (DOI:10.4414/smw.2013.13838).