Quantitative electroencephalography in Parkinson's disease, dementia, depression and normal aging.

The relationship between depression and dementia in Parkinson's disease (PD) has rarely been explored. Using a quantitative EEG (qEEG) parameter, we studied four groups of subjects: PD, demented Alzheimer's type and major depressed patients and normal controls. The qEEG data were compared with those of the Mini-Mental State and the Hamilton Depression Scale. The qEEG pattern was different in the four groups of subjects. Moreover, there was a significant correlation between the qEEG data and the other variables, and, particularly, with the cognitive performances. Our findings demonstrate that the qEEG method of assessment may give valuable data for a better classification of dementia syndromes and for a distinction between dementia and pseudodementia.