Dementia, mild cognitive impairment and quantitative EEG in patients with Parkinson's disease.

The objective of this study was to evaluate relationships between quantitative EEG (qEEG) changes and cognitive disturbance (mild cognitive impairment or dementia) and the motor disturbance stage in Parkinson's disease (PD). Thirty-two PD patients (age = 67.2 +/- 10.0) and 26 normal subjects (age = 68.4 +/- 4.7) were assessed using a neurological evaluation, modified Hoehn and Yahr (HY) scale for PD, a Portuguese version of the CERAD neuropsychological battery (consortium to establish a registry for Alzheimer's disease) incorporating the Mini-mental Status Examination, Clinical Dementia Rating and an EEG analysis of absolute and relative band amplitude at rest. Four groups were compared: three with PD (7 patients with dementia, 10 with mild cognitive impairment and 15 with no cognitive disturbances) and the control group. The qEEG showed no significant differences between the control group and PD patients without cognitive disturbance. Abnormalities on the qEEG were essentially associated with the occurrence of mild cognitive impairment or dementia in patients with PD. There was an increase in the absolute and relative posterior theta amplitude in the groups with mild cognitive impairment or dementia and of the posterior absolute and relative delta amplitude in the group with dementia This study suggested qEEG as a possible physiological tool in the assessment of cognitive aspects in PD.