Specific angles and sharpness of brain waves seen in unfiltered raw data from scalp; electroencephalograms have been tying to Parkinson’s disease. Reporting in the online journal eNeuro, researchers suggest that noninvasive EEG readings may provide easily detectable electrophysiological biomarkers to aid the diagnosis and fine-tune therapeutic treatments for the disease and potentially other motor disorders.
“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,” said the study’s principal investigator Nicole Swann; of the Department of Human Physiology at the University of Oregon. The initial diagnosis of Parkinson’s disease currently relies on a neurologist’s assessment of patients; performing a series of body-movement tasks. Such subjective testing, however, can lead to misdiagnosis.
“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 said. Previous efforts to detect Parkinson’s disease in EEG brain waves; have been inconsistent, she said, because the focus on measures which model brain signals as sine waves; which are beta waves filtered to round the waves and show the overall power of periodic oscillations.
Clinical observations and other EEG measurements
Novel methods like the one used here currently have only been shown to relate to Parkinson’s disease; with electrodes surgically implanted in patients’ brains. In the new analysis of scalp EEG data, previously collected at the University of California San Diego from 15 Parkinson’s patients; and 16 healthy control participants, Swann focused on the original unfiltered beta waves to look for specific angles; and full shape of the oscillations. Co-author Scott Cole, a doctoral student at UC San Diego in 2017, had noticed that people with Parkinson’s disease; appear to have sharp brain waves, suggesting a new look was warranty.
“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.” When the peak is sharper at the top of the wave than in the trough; or low part of the oscillation, it is indicative of patients who are off their medications, she said.
In a large follow-up study, Swann said she hopes to combine scalp EEG measurements with detailed medical histories and self-reports of how patients are feeling on each day of testing. Eventually, it is hope the approach could help detect changes in the disease in individuals over time.
An electric stimulator
Current treatment involves surgery to permanently implant an electric stimulator; but a pharmacological approach in which dosage titration is difficult and often results; in frustrating cycling of effectiveness, said study co-author Bradley Voytek; a neuroscientist at UC San Diego, in whose lab Cole, who has since earned his doctorate, had worked.
“If there were real-time measures of how effective treatments are at reducing the negative symptoms of Parkinson’s disease; treatments could be adjust in real-time,” Voytek said. “In the case of an invasive brain stimulator, this might mean only applying electric stimulation when it’s need. But in the case of pharmacology, it would mean adjusting a drug’s dose much like continuous glucose monitoring done by an implant can signal a pump to adjust insulin levels as needed.”
Ideally, Swann said, if the approach proves to provide robust information, EEG testing could be remotely done by Parkinson’s patients wearing a hat fitted with electrodes. But results could be sent to their neurologists and used to quickly and easily adjust treatments. A challenge, Voytek said, is that real-time measures of brain activity are often noisy and can cloud the ability to capture the correct signals. “A lot of the tools we have for measuring them take a lot of processing power, so they can’t easily be applied in real-time,” he said.