The REM sleep behavior disorder screening questionnaire: Validation study of a Japanese version

Background: REM sleep behavior disorder (RBD) is a parasomnia characterized by intermittent loss of normal skeletal muscle atonia during REM sleep and elaborate motor activity associated with dream mentation. Idiopathic RBD (iRBD) has a known association with neurodegenerative diseases such as synucleinopathies. Recently, a specific screening scale for assessment of REM sleep behavior disorder (RBDSQ) was validated. Detection of RBD using a Japanese version of the RBDSQ would be useful in the stepwise diagnostic process. We investigated the validity and reliability of a Japanese version of this instrument, the RBDSQ-J. Methods: Subjects were 52 patients with iRBD diagnosed according to criteria in the International Classification of sleep disorders, second edition, 55 obstructive sleep apnea syndrome (OSAS) patients who responded well to CPAP therapy after a diagnosis of RBD was ruled out by history and polysomnography (PSG) and 65 healthy subjects. Results: An RBDSQ-J score cut-Off of 5.0 was considered useful for differentiating the iRBD group from the healthy subjects or the OSAS group. Cronbach's alpha for the entire RBDSQ-J was 0.866. Conclusion: The RBDSQ-J had high sensitivity, specificity, and reliability and would be applicable as a screening method for iRBD in the elderly Japanese population. (C) 2009 Elsevier B.V. All rights reserved.