Probable RBD and association with neurodegenerative disease markers: A population-based study.

BACKGROUND: The prevalence of rapid eye movement sleep behavior disorder (RBD) and its association with markers of neurodegeneration in the general population are poorly defined. METHODS: We assessed the prevalence of probable RBD defined by two validated questionnaires, the RBD Screening Questionnaire (RBDSQ) and the Innsbruck RBD-Inventory (RBD-I), and studied its associations with clinical and imaging markers for neurodegeneration in the Bruneck Study cohort aged 60 y or older. RESULTS: Of the 456 participants without Parkinson's disease, 4.6% (RBDSQ; 95%CI, 3.0%-7.0%) and 7.7% (RBD-I; 95%CI, 5.6%-10.5%) had probable RBD. Probable RBD diagnosed with either of the questionnaires was associated with hyposmia (trend; P < 0.1), anxiety (P < 0.05), depression (P < 0.05), antidepressant use (P < 0.05), and self-reported non-motor symptoms (P < 0.01), specifically, dribbling saliva, memory problems, apathy, concentration problems, and anxiety. CONCLUSIONS: Our findings may provide a basis for future studies intending to identify cohorts at risk for Lewy body diseases through screening of the general elderly population for RBD.

Validity of the Japanese version of the REM Sleep Behavior Disorder (RBD) Screening Questionnaire for detecting probable RBD in the general population.

AIMS: In order to evaluate the validity of the REM Sleep Behavior Disorder (RBD) Screening Questionnaire (RBDSQ) as a screening tool for RBD in a general population setting, we conducted a validation study using residents of a rural community. METHODS: We sent questionnaires that included the RBDSQ to 2631 eligible adult residents in the town of Daisen, Japan. RESULTS: Of those residents, 1572 participants (59.7%) gave complete answers to the RBDSQ. Among them, 179 participants (11.4%) scored ≥5 points on the questionnaire; an additional 149 participants scoring ≤4 points were randomly selected for further telephone interview. Based on obtained results, nine participants (0.57%) were judged as having probable RBD. Receiver-operator curve analysis revealed that a total score of 6 points on the RBDSQ represented the best cut-off value for detecting probable RBD (sensitivity: 100%; specificity: 73.0%). Analysis based on the item response theory revealed that items 1, 4, 6-1, 7, and 8 had lower difficulty than the remaining items, suggesting that these items are more essential in the screening for probable RBD. CONCLUSIONS: The present study revealed that a score of 6 points on the RBDSQ could be used as a cut-off value for the screening of probable RBD in the general population. Evaluation of the distribution of positive items might be helpful for identifying the intensity of a person's RBD symptoms.

Body-First Subtype of Parkinson's Disease with Probable REM-Sleep Behavior Disorder Is Associated with Non-Motor Dominant Phenotype.

BACKGROUND: The hypothesis of body-first vs. brain-first subtype of PD has been proposed with REM-Sleep behavior disorder (RBD) defining the former. The body-first PD presumes an involvement of the brainstem in the pathogenic process with higher burden of autonomic dysfunction. OBJECTIVE: To identify distinctive clinical subtypes of idiopathic Parkinson's disease (iPD) in line with the formerly proposed concept of body-first vs. brain-first subtypes in PD, we analyzed the presence of probable RBD (pRBD), sex, and the APOEɛ4 carrier status as potential sub-group stratifiers. METHODS: A total of 400 iPD patients were included in the cross-sectional analysis from the baseline dataset with a completed RBD Screening Questionnaire (RBDSQ) for classifying as pRBD by using the cut-off RBDSQ≥6. Multiple regression models were applied to explore (i) the effect of pRBD on clinical outcomes adjusted for disease duration and age, (ii) the effect of sex on pRBD, and (iii) the association of APOEɛ4 and pRBD. RESULTS: iPD-pRBD was significantly associated with autonomic dysfunction (SCOPA-AUT), level of depressive symptoms (BDI-I), MDS-UPDRS I, hallucinations, and constipation, whereas significantly negatively associated with quality of life (PDQ-39) and sleep (PDSS). No significant association between sex and pRBD or APOE ɛ4 and pRBD in iPD was found nor did we determine a significant effect of APOE ɛ4 on the PD phenotype. CONCLUSION: We identified an RBD-specific PD endophenotype, characterized by predominant autonomic dysfunction, hallucinations, and depression, corroborating the concept of a distinctive body-first subtype of PD. We did not observe a significant association between APOE ɛ4 and pRBD suggesting both factors having an independent effect on cognitive decline in iPD.