A study published in Neurology demonstrates that excessive daytime sleepiness (EDS), REM sleep behavior disorder (RBD), and high levels of autonomic symptoms predict the risk for long-term psychotic symptoms in patients with Parkinson disease (PD).

A total of 423 patients with newly diagnosed, treatment-naïve PD who were included in the Parkinson Progression Markers Initiative (PPMI) were included in this cohort study. The Movement Disorders Society-Unified Parkinson Disease Rating Scale (MDS-UPDRS) item 1.2 was used to evaluate psychotic symptoms. Also, the Scales for Outcomes in Parkinson’s Disease–Autonomic, the RBD Screening Questionnaire, and the Epworth Sleepiness Scale were used at baseline. The primary outcome was comprised of the number of psychotic events at follow-up.

The multivariate logistic regression analysis, which was adjusted for age and sex, showed that the presence of RBD (odds ratio [OR] 1.9, P =.021), EDS (OR 2.5, P =.003), and greater autonomic symptom burden (OR 1.07 [for a 1-unit change in SCOPA-AUT], P =.002) at baseline were associated with an increased risk for experiencing psychotic symptoms on ≥2 occasions. In addition, the presence of two to three of these symptoms at baseline was associated with significantly lower Ch4 density (P =.007). According to a logistic regression model, the investigators found that greater Ch4 gray matter density correlated with lower risk for psychotic symptoms on ≥2 occasions (OR 0.96 [for an increase in density of 1 unit], P =.03).

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Findings from this study support associations rather than causal links between psychotic events and EDS, RBD, and autonomic symptoms. In addition, assessment of psychiatric symptoms relied on only one question in the MDS-UPDRS, potentially leading to underestimation of these symptoms in this cohort.

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The association between EDS, RBD, and autonomic symptom burden “and lower Ch4 density supports the potential utility of this neuroimaging biomarker to identify a diffuse malignant subtype of PD and to predict more rapid disease progression,” the investigators noted.


Barrett MJ, Blair JC, Sperling SA, Smolkin ME, Druzgal TJ. Baseline symptoms and basal forebrain volume predict future psychosis in early Parkinson disease [published online April 4, 2018]. Neurology. doi:10.1212/WNL.0000000000005421