The patterns of EEG changes in early-onset Parkinson's disease patients.

The aim of this study was to investigate the patterns of brain activity changes in early-onset Parkinson's disease (EOPD) patients and its relationship with the severity of disease and motor deterioration. Electroencephalography (EEG) was performed in a sample of 52 nondemented EOPD patients and 20 healthy controls with similar age. All patients underwent a battery to assess PD severity and motor deterioration. The EEG data were rated by visual and quantitative analyses with the grant total EEG (GTE) score and NicoletOne Software. The parameters of relative band power and coherences for various frequency bands were calculated. In addition, all parameters were compared between groups and examined for correlations with the severity of disease and motor deterioration. The GTE score and two subscores including "Diffuse Slow Waves" and "Frequency of Rhythmic Background Activity" of EOPD increased comparing to control group. The relative beta band powers in seven regions (O1,O2,T5,T6,P3,P4 and C3) indicated significant decreases in EOPD patients and obvious increases in interhemispheric beta coherences were observed in the midtemporal area and frontal area (T3T4 and F3F4). Furthermore, correlation analyses revealed that longer duration was associated with the subscore of "background wave frequency". The beta frequency bands in the right posterior temporal (T6) showed negative relationship with the modified Hoehn-Yahr grading scores. This study is the first to depict the patterns of EEG changes in EOPD patients without dementia and offer a better understanding of the pathophysiological mechanisms underlying and prognostic purposes in EOPD. Some of these changes could serve as useful biomarkers in the study of EOPD.