EEG in demented and non-demented parkinsonian patients.

The electroencephalograms (EEG) of patients with Parkinson's disease (PD) were evaluated in relation to age, mental status and motor disability. Abnormalities, particularly mild slowing, were observed in 34% of 128 patients and more frequently in the elderly. While a slowing in occipital background activity was more frequent in demented patients, a statistically significant association was also observed between the degree of motor disability and the frequency of slowing in occipital background activity in mentally intact patients. This correlation may suggest that subcortical structures (involved in motor control) influence occipital background activity.