Sleep-related hallucinations in patients with Parkinson's disease

Given that sleep-wake cycle dysfunction can cause hallucinations in Parkinson's disease patients, sleep-related hallucinations may be a different subtype from hallucinations that occur only during full wakefulness. However, few studies that distinguish the onset situations of hallucinations related to sleep from those that occur in full wakefulness have been conducted to investigate hallucinations in Parkinson's disease patients. Therefore, we conducted a multicenter observational study to investigate the prevalence of and factors associated with sleep-related hallucinations in patients with Parkinson's disease. Information on hallucinations was collected by using a questionnaire and face-to-face interviews. Of 100 consecutive patients with Parkinson's disease, 29 (29%) reported sleep-related hallucinations, and 16 (16%) reported hallucinations only in the full wakefulness. A longer duration of Parkinson's disease treatment (OR 1.35, 95% CI 1.07 to 1.72), higher Beck Depression Inventory-II scores (OR 1.07; 95% CI 1.01 to 1.14), and higher rapid eye movement sleep behavior disorder scores (OR 5.60; 95% CI 1.54 to 20.38) were independent factors associated with the presence of sleep-related hallucinations in a multivariable analysis. Sleep-related hallucinations, but not daytime hallucinations, were associated with probable rapid eye movement sleep behavior disorder. Phenomenological discrimination between sleep-related hallucinations and daytime hallucinations is important for elucidating the full pathology in Parkinson's disease and the mechanisms underlying hallucinations.