A quantitative study of the electroencephalographic response to levodopa treatment in parkinsonian patients.

A quantitative EEG study was done in order to confirm previous impressions that there is a significant EEG response to levodopa in parkinsonian patients, and in order to trace the existence of dopaminergic mechanisms in the generation of the human EEG. EEGs of twenty-five parkinsonian patients were recorded both before and during levodopa treatment, two to four weeks apart, when levodopa doses reached maintenance levels of 3-5g/d. Derivations from F7-T3, F8-T4, T5-O1, and T6-O2 were recorded and digitally processed into power density spectra. These spectra were analyzed for levodopa effects in a full factorial repeated measures multiple analysis of variance (MANOVA). A significant effect of levodopa treatment on the EEG was found, and localized to the left occipital lobe. This effect manifested as an increase in power in all the EEG frequency bands. These findings are compatible with multiband synchronization of the EEG generating processes, attributable to dopaminergic mechanisms.