Characteristics of cognitive function in patients with Parkinson's disease: a comparison with healthy subjects

The object of the present study was to evaluate the visual event-related potentials (ERPs) and the effects of emotion in patients with Parkinson disease without dementia. Visual ERPs were recorded using an oddball paradigm in 18 patients and 18 age-matched healthy subjects. The P300 amplitude and latency, as well as the subject's reaction time were recorded. There was no difference in the P300 amplitude between patients and controls when viewing a smiling baby or viewing a crying baby. The P300 amplitude when viewing a smiling baby was smaller than that when viewing a crying baby for the both patients and the healthy controls. The P300 amplitude was significantly larger in the stage 3 group than in the stage 4 group as classified by Hoehn and Yahr. The P300 latency in patients was significantly longer both in group 3 and group 4 patients than that in the healthy controls, in response to both the facial stimuli. These results indicate that patients with Parkinson diseases are likely to have cognitive dysfunction and that ERPs are biological markers useful for the evaluation of patients. These results also suggest that the P300 is influenced by affective facial expressions and that the effects for patients are essentially similar to healthy controls.