Baseline symptoms and basal forebrain volume predict future psychosis in early Parkinson disease

Objective Determining baseline predictors of future psychosis in Parkinson disease (PD) may identify those at risk for more rapidly progressive disease, i.e., a more malignant PD subtype. Methods This cohort study evaluated 423 patients with newly diagnosed PD collected as part of the Parkinson's Progression Markers Initiative. Psychotic symptoms were assessed with the Movement Disorders Society-Unified Parkinson Disease Rating Scale item 1.2, which assesses hallucinations and psychosis over the past week. At baseline, participants completed the Scales for Outcomes in Parkinson's Disease-Autonomic, the REM Sleep Behavior Disorder (RBD) Screening Questionnaire, and the Epworth Sleepiness Scale. Cholinergic nucleus 4 (Ch4) density was calculated for 228 participants with PD and 101 healthy controls. Results Multivariate logistic regression adjusted for age and sex found that greater autonomic symptoms (p = 0.002), RBD (p = 0.021), and excessive daytime sleepiness (EDS) (p = 0.003) at baseline were associated with increased risk of reporting psychotic symptoms on >= 2 occasions. Having 2 or 3 of these baseline symptoms was associated with lower Ch4 density (p = 0.007). In a logistic regression model adjusted for age and sex, higher Ch4 gray matter density was associated with lower risk of reporting psychotic symptoms on >= 2 occasions (odds ratio 0.96 [for an increase in density of 1 unit], p = 0.03). Conclusions This study confirms that RBD, EDS, and greater autonomic symptom burden are associated with greater risk of future psychotic symptoms in PD. Reduced Ch4 density at baseline is associated with future psychotic symptoms and a greater burden of RBD, EDS, and autonomic symptoms.