Abnormal occipital event-related potentials in Parkinson's disease with concomitant REM sleep behavior disorder

Rapid eye movement sleep behavior disorder is found in 33-46% of patients with Parkinson's disease and was shown to be associated with cognitive deficits. Our goal was to improve our understanding of the role of this sleep disorder in cerebral dysfunction occurring in Parkinson's disease using a visual cognitive task and event-related potentials.

Sixteen patients with Parkinson's disease and rapid eye movement sleep behavior disorder, 15 patients with Parkinson's disease without rapid eye movement sleep behavior disorder and 16 healthy control subjects were included. The amplitude and latency of event-related potentials were compared between groups.

No group differences were found for reaction times or accuracy. A Group effect was found for P2 wave amplitude; patients with rapid eye movement sleep behavior disorder had increased P2 in comparison with the control group (p < 0.05). Patients with Parkinson's disease alone were not different from the two other groups for this component. Prolonged novelty P3 latencies on Cz were associated with longer disease durations among patients with Parkinson's disease (p < 0.01).

Co-morbid Parkinson's disease and rapid eye movement sleep behavior disorder were associated with abnormal visual P2 component of event-related potentials. Although patients with Parkinson's disease alone were not significantly different from patients with combined Parkinson's disease and rapid eye movement sleep behavior disorder, their P2 amplitudes were not sufficiently abnormal to differ from that of control subjects. This study confirms that rapid eye movement sleep behavior disorder accentuates cerebral dysfunctions in Parkinson's disease.