Parkinson's disease and narcolepsy-like symptoms

Various sleep-related problems, for example, insomnia and symptoms of rapid eye movement behavior disorder (RBD), are common in patients with Parkinson's disease (PD). We studied the prevalence of symptoms of narcolepsy (NARC), hallucinations, and RBD and their association with other symptoms.

Altogether, 1447 randomly selected patients with PD, aged 43-89 years, participated in a questionnaire study. A structured questionnaire with 207 items was based on the Basic Nordic Sleep Questionnaire. Questions on demographics, PD, RBD, and other issues were included.

The response rate was 59.0%; of these patients, 73% had answered to all questions that were used in the analyses (N = 623). The occurrence of suspected narcolepsy (Ullanlinna Narcolepsy Scale ≥ 14 and Epworth Sleepiness Scale ≥ 11) was observed in 9.3% of the subjects (PD with NARC), RBD (REM Sleep Behavior Disorder Screening Questionnaire ≥ 6) in 39.2% of all patients with PD, and in 62.1% of those with PD and NARC. In patients with PD, hallucinations before going to bed in the evening occurred in 5.8%, hypnagogic hallucinations in 4.0%, hallucinations during night 8.3%, and hypnopompic hallucinations in 3.2%. Cataplexy symptoms occurred in 43.1% of subjects with PD and NARC. In a logistic regression analysis, PD with NARC was associated with RBD, all types of hallucinations, daytime sleepiness, fatigue, insomnia, and intense dreaming also when adjusted for age, sex, disease duration, and levodopa.

Narcolepsy-like symptoms may be present in patients with PD. Symptoms of RBD were associated with symptoms of narcolepsy including symptoms of cataplexy.