Investigation of non-linear properties of multichannel EEG in the early stages of Parkinson's disease.
OBJECTIVE
Modifications of brain activity in the early stages of Parkinson's disease (PD) are difficult to detect using electroencephalography (EEG) signals and are often biased by L-DOPA treatment. We compare here the performances of both linear and non-linear methods in differentiating EEG of L-DOPA naive PD patients from that of control subjects.


METHODS
Resting multichannel EEG (20 electrodes, 30 s epochs) of 9 patients with PD in Hoehn and Yahr stages 1-2 (4 women, 5 men, mean age 54.3 years, range 48-63 years) were compared with those of 9 control subjects (7 women, two men, mean age 51.3 years, range 43-61 years). The following measurements were computed: theta-, alpha- and beta-band relative powers constituted the linear indices; localized entropy, slope asymmetry and number of non-linear EEG segments constituted the non-linear indices.


RESULTS
In the case of linear quantification, only a decrease in the beta-band was observed for patients. Significant non-linear structures were observed in our EEG data. Non-linear quantifiers demonstrate an increase in entropy and in the number of non-linear EEG segments for the patients.


CONCLUSIONS
Changes in EEG dynamics observed here in L-DOPA naive PD patients may represent early signs of cortical dysfunction produced by subcortical dopamine depletion.
Pezard
L
L
Laboratoire de Neurosciences Comportementales, Université René Descartes, 45 rue des Saints-Pères, F-75270 Cedex 06, Paris, France.
Jech
R
R
Růzicka
E
E
D000465:Algorithms; D000978:Antiparkinson Agents / Q000627:therapeutic use; D004569:Electroencephalography; D019277:Entropy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D010300:Parkinson Disease / Q000188:drug therapy / Q000503:physiopathology* / Q000523:psychology; D011569:Psychiatric Status Rating Scales
D000978:Antiparkinson Agents