Results from a study show that patients with PD who are off medication have more asymmetric brain waves than those on medication, and that medication decreases this asymmetry.
“Converging work has shown that PD is associated with excessive beta synchrony. Here we show that this pathophysiological synchrony is manifest in a change in waveform shape which can be detected at the scalp,” wrote senior author Nicole Swann, PhD, of the University of Oregon, Eugene, OR, and colleagues.
Results showed that patients with PD who are off medication have more asymmetric brain waves than those on medication, and that medication decreases this asymmetry.
“Waveform shape is a putative non-invasive electrophysiology biomarker of PD state with potential utility for assessing treatments, monitoring disease, or diagnosis. This signature can be detected with a safe, affordable, and available method (i.e. EEG),” they added.
Diagnosis and monitoring of PD mainly relies upon clinical rating scales that can be imprecise. Having a more objective test, especially a noninvasive one, may improve diagnosis and management of PD.
To investigate the issue, researchers used resting scalp EEG to evaluate 15 PD patients (8 female, mean age 63.2 years) on and off dopaminergic medication for at least 12 hours, and 16 healthy, age-matched controls (9 females, mean age 63.5 years). The study took place at a single movement control clinic in La Jolla, California.
Beta wave oscillation in PD patients off medication were significantly sharper and steeper than in PD patients on medication (p<0.02), the authors found.
PD patients off medication also had significantly higher PAC, or phase amplitude coupling between beta and gamma waves (PAC refers to the phenomenon in which slower brain wave oscillations modulate faster ones, which may play a role in information processing in the brain) (p=0.017).
The authors hypothesized that the changes in waveform shape may measure underlying brain pathophysiology in PD: excessive beta synchrony.
“This synchrony exists in the healthy state, but is amplified throughout motor networks, both within and between individual structures in PD. Dopaminergic medication reduces this excessive synchrony, in conjunction with improvement of the Parkinsonian state, which is reflected in the reduction of PAC, sharpness ratio, and steepness ratio,” they wrote.
They mentioned several potential applications for these results. A noninvasive PD biomarker could be used to adjust medication dosage amount and timing, or to more precisely adjust deep brain stimulation settings. It could even be used for automatic programming of DBS, which may obviate the need for clinical appointments for adjustment.
“These approaches may be especially useful for PD patients who lack easy access to neurologists, especially those who are mobility impaired or live in remote areas. With increases of wearable technology, one could imagine that acquiring these measures could become increasingly easy even in patients’ own homes,” they wrote.
The study had a small number of participants and took place at a single center. So results need to be confirmed in a larger, more diverse group of patients.
1. Jackson N, Cole SR, Voytek B, et al. Characteristics of Waveform Shape in Parkinson's Disease Detected with Scalp Electroencephalography. eNeuro. 2019 May 20. pii: ENEURO.0151-19.2019. doi: 10.1523/ENEURO.0151-19.2019.