Measuring the electric brain activity of people with Parkinson’s may be a non-invasive and accurate way of diagnosing the disease and monitoring response to treatment, a study suggests.
The study, “Characteristics of Waveform Shape in Parkinson’s Disease Detected with Scalp Electroencephalography,” was published in the journal eNeuro.
The brain produces brainwaves in specific patterns characterized by smooth period oscillations, which to some extent represent how the brain works. Brain oscillations refer to the rhythmic electrical activity generated both spontaneously and in response to stimuli. Scientists have proposed that these oscillations could have a different shape in people with Parkinson’s, and several other neurological diseases, than what is seen in healthy people.
Diagnosing and monitoring Parkinson’s disease is now based on clinical rate scales that can be subjective, relying on the opinion of the neurologist or other expert reviewing movement tests that make up these scales. Researchers in this study suggest that analyzing irregular (non-sinusoidal) brainwave features in waveform shapes, as detected by an electroencephalogram (EEG), can be useful in characterizing Parkinson’s disease and treatment response.
EEG is a common and non-invasive test to capture brain neural activity. It uses small metal discs, called electrodes, attached to a person’s scalp together with a conducive gel that enhances brain signals.
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“Using this safe and affordable way to measure and quantify brain activity, we were able to distinguish differences between Parkinson’s patients who were on and off medications and in comparisons with healthy people,” Nicole Swann, PhD, assistant professor at the University of Oregon and the study’s senior author, said in a press release.
“We don’t know yet whether this approach will be better, but it could provide easily obtained brain measurements that would be helpful and possibly used in tandem with clinical observations and other EEG measurements,” Swann added.
Researchers from the University of Oregon and the University of California San Diego focused on analyzing unfiltered raw brain waves, and looked for differences in shape oscillations and their specific angles. Such efforts, to date, have only been tried with Parkinson’s using electrodes surgically implanted in patients’ brains.
The team collected EEG data from 15 Parkinson’s patients, with a mean age of 63.2 and eight of whom were women, and 16 healthy age-matched volunteers. The patients were on and off dopaminergic medication.
Data showed that patients off such medications had a sharper wave peak at the top of the oscillation than in its trough, or low part.
“The raw signals go up and down like sine waves but with more asymmetry,” Swann said. “The steepness — the slant — turns out to be important in Parkinson’s patients. This was easily detectable in the patients who are off medication,” added Scott Cole, a UC San Diego researcher and study co-author.
“Here we show that this pathophysiological synchrony [excessive beta wave synchrony] is manifest in a change in waveform shape which can be detected at the scalp,” the study concludes. “Specifically, we show waveforms are more asymmetric for PD patients off medication and that this is reduced with medication.”
If this new approach proves to be an accurate and easy way of determining a patient’s status, it might lead to treatment adjustments that can be made in real-time. It may also help in detecting the disease.
Further studies are necessary because accurate measures of electric brain activity can be challenging. Swann and her team hope to combine EEG data collected in such a non-invasive way with detailed patient medical history in a large study, to better evaluate this method’s accuracy.
Still, “our findings highlight the importance and value of considering waveform shape for future EEG studies,” the researchers wrote.