View Full Version : Maybe, possibly, a hint that EEG might be useful.


Amtram
10-09-13, 04:41 PM
UC Davis does some excellent work on brain research, and is a wealth of information on ADHD and ASD. Last year, the American Association of Pediatrics released a paper suggesting that EEG might show some promise as a diagnostic tool for ADHD. I thought it was premature, and still haven't seen anything that looks like an enormous breakthrough, but this is another one of the findings that show that it may have some potential uses.

UC Davis study finds potential biomarker differentiating the inattentive and combined subtypes of ADHD (http://www.ucdmc.ucdavis.edu/publish/news/newsroom/8228)

This was a small study, and all the subjects were teenagers. The article does not specify if there were medicated vs. unmedicated controls. However, the subjects were separated into Inattentive and Hyperactive-Impulsive groups, and non-ADHD controls. The test measured both brain wave response and physical response time.

It showed not only differences between ADHD and control subjects, but differences between the two types of ADHD subtypes.

Not ready for prime-time, but an interesting study from what is usually a reliable source, so we may see some more EEG-based studies in the future following up on this.

Amtram
10-12-13, 10:38 AM
And. . .just as expected, Google is now loaded with articles proclaiming that "Brain Scans Can Diagnose ADHD." A couple of articles actually are more sensible than their SEO-written headlines would lead you to believe, but I really don't want to link to them because they are wretched sites that don't deserve the traffic.

One elaborates a little more on the testing model:

The teens' brain waves were assessed using EEG caps with 32 electrodes. Some cues were more helpful than others, so the task required the participants to sometimes override an initial impulse in order to respond correctly. Such situations are particularly challenging for people with ADHD, researchers noted.

Overall, the 23 typically developing (TD) teens had the fastest response times and the most correct responses compared with the other two groups.

The CB group had the lowest number of correct answers and the slowest response times. And a post-hoc analysis showed that both the TD and IA groups had significantly faster reaction times than the CB group.
Researchers found that these differences among the groups also correlated with differing brain waves patterns -- illustrating that these groups display distinct physiological profiles.

In the part of the test called response preparation cue, where the teens were told that a particular color (blue or yellow) of a cartoon hand would elicit the right answer, researchers found significant differences in alpha wave suppression.

Alpha wave suppression is required when a person must extract features from a visual stimulus to make sense of it. In other words, it filters out the noise.

The TD group had the largest amount of alpha suppression, while the IA group had the least -- suggesting their noise-filtering mechanism was less than optimal.

Although the CB group fit somewhere in the middle, there was no statistical difference between the CB and IA groups in terms of alpha suppression.

Furthermore, the more alpha suppression in the TD group, the greater the number of correct responses. No such correlation was found in either the CB or IA groups.

Researchers found similar results regarding beta wave changes in the brain's motor cortex.

The greatest amount of beta suppression occurred in the TD group after the response preparation cue. The CB group had the least amount of beta suppression. The difference between the IA and CB groups was not significant.

"Our study suggests differential impairment profiles in the ADHD subtypes, and not simply an additive effect of impairments in the ADHD combined subtype," said co-author Catherine Fassbender, PhD, a research scientist with the UC Davis M.I.N.D. Institute, in a statement.
"The inattentive group had problems processing the cues, whereas the combined type had problems using the cues to prepare a motor response," she pointed out.

In the null cue part of the test, where no information was given regarding right or wrong answers, the groups did not display any difference in alpha suppression.

In addition, the alpha suppression in this part of the test was significantly less than in the previous response preparation cue test -- "suggesting the null cues were not processed to the same extent in the visual cortex."
Nine of the 17 teens in the IA group were taking medication for ADHD, and researchers found no difference in alpha suppression between the medicated and nonmedicated IA participants.

It also has this useful tidbit of information:

Because they'd need more than 850 participants to detect a significant difference -- if one existed -- researchers concluded that medication differences "were unlikely to account for our alpha suppression findings."

The study size was less than 10% of that number. 57 participants, folks. This is preliminary research being used to validate a hypothesis as worthy of further study.

Another article points out that one of the goals of the study is to provide not only a differential diagnosis, but to show a concrete demonstration that ADHD actually exists. Because, you know, otherwise we're all just faking it. /snark.

The likelihood of this research providing a usable diagnostic tool or treatment modality is a lot smaller in the short run than providing validation of ADHD as a condition, but I suppose that the latter is kind of a worthy goal as well.