Quantitative EEG reflects non-dopaminergic disease severity in Parkinson's disease

Abstract

Objective: In Parkinson’s Disease (PD), measures of non-dopaminergic systems involvement may reflect disease severity and therefore contribute to patient-selection for Deep Brain Stimulation (DBS). There is currently no determinant for non-dopaminergic disease severity. In this exploratory study, we investigated whether quantitative EEG reflects non-dopaminergic disease severity in PD. Methods: Sixty-three consecutive PD patients screened for DBS were included (mean age 62.4 ± 7.2 years, 32% females). Relative spectral powers and the Phase-Lag-Index (PLI) reflecting functional connectivity were analysed on routine EEGs. Non-dopaminergic disease severity was quantified using the SENS-PD score and its subdomains; motor-severity was quantified using the MDS-UPDRS III. Results: The SENS-PD composite score correlated with a spectral ratio ((d + h)/(a1 + a2 + b) powers) (global spectral ratio Pearson’s r = 0.4, 95% Confidence Interval (95%CI) 0.1–0.6), and PLI in the a2 band (10–13 Hz) (r = 0.3, 95%CI 0.5 to 0.1). These correlations seem driven by the subdomains cognition and psychotic symptoms. MDS-UPDRS III was not significantly correlated with EEG parameters. Conclusions: EEG slowing and reduced functional connectivity in the a2 band were associated with non-dopaminergic disease severity in PD. Significance: The described EEG parameters may have complementary utility as determinants of non-dopaminergic involvement in PD.