High delta and gamma EEG power in resting state characterise dementia in Parkinson’s patients

Abstract

• We compare EEG power changes in PD with or without dementia. • Higher power in delta and gamma bands differentiate PD dementia stage form PD non-dementia stage. • Changes in delta power occur globally over the scalp. • Power in gamma band changes in right frontal and centro-parietal regions. Parkinson’s disease (PD) is a chronic neurodegenerative disease with appearance of dementia as the disease progresses. Dementia in PD worsens the quality of life and poses a burden on caregivers. Objective markers of the presence and as well as onset of dementia needs to be explored to improve the quality of life. We attempted to identify EEG abnormalities that differentiate PD patients with or without dementia using high density EEG. The differential changes in the EEG spectral activity could mark the early stage as well as onset of dementia in Parkinson’s disease (PD). The present study was designed to find out the resting eyes-closed (EC) EEG characteristics in PD with dementia (PDD) and without dementia (PDND) compared to healthy controls (CON) of both gender using high density EEG. Absolute power of seven frequency bands based on individual alpha frequency was estimated by Fast Fourier transform algorithm in 58 PD patients (30 PDND and 28 PDD) and 26 CON. Compared to CON, PDND had higher power in theta and lower alpha1 bands while PDD had higher power in delta, theta, lower alpha1 and beta bands. Higher delta and gamma power with no difference in theta and lower alpha 1 power was the characteristic feature of PD patients with dementia compared to non-dementia. This cross-sectional study proposes to use these differential changes in power as EEG signatures of appearance of dementia in PD. Absence of high delta power, but presence of high theta and lower alpha 1 power defined PDND group compared to CON.