REM Sleep Behavior Disorder and Its Possible Prodromes in General Population

Abstract

<h3>Objective:</h3> To evaluate the prevalence of REM sleep behavior disorder (RBD) and its possible prodromal conditions, isolated dream-enactment behavior (DEB) and isolated REM without atonia (RWA), in a general population sample, and the factors associated with diagnosis and symptom frequency. <h3>Methods:</h3> From a population-based prospective cohort in Korea, 1,075 subjects (age 60.1±7.0 years; range 50–80 years; men 53.7%) completed the RBD screening questionnaire (RBDSQ), a structured telephone-interview for the presence and characteristics of repeated DEB, and home polysomnography. REM without atonia (RWA) was measured on submentalis EMG, including 30-second epoch based tonic and phasic activity as well as 3-second mini-epoch based phasic and any EMG activities. Based on the presence of repeated DEB and any EMG activity of ≥22.3%, we categorized the subjects into no RBD, isolated RWA, isolated DEB, and RBD groups. <h3>Results:</h3> RBD was diagnosed in 20, isolated RWA in 133 subjects, and isolated DEB in 48 subjects. Sex and DEB frequency-adjusted prevalence of RBD was 1.4% (95% confidence interval [CI] 1.0–1.8%), isolated RWA 12.5% (95% CI 11.3–13.6%), and isolated DEB 3.4% (95% CI 2.7–4.1%). Total RBDSQ score was higher in the RBD and isolated DEB groups than in the isolated RWA and no RBD group (median 5, interquartile range [IQR 4–6] for RBD, median 4 [IQR 3–6] for isolated DEB, median 2 [IQR 1–3] for isolated RWA and median 2 [IQR 1–4] for no RBD groups, <i>P</i>&lt;0.001). RBDSQ score of ≥5 had good specificity but poor positive predictive value (PPV) for RBD (specificity 84.1% and PPV 7.7%) and its prodromal conditions (specificity 85.2% and PPV 29.1%). Among the RWA parameters, any EMG activity showed the best association with the RBD and its possible prodromes (area under the curve, 0.917). 3-second mini-epoch based any EMG activity and phasic EMG activity were correlated with the frequency of DEB (standardized Jonckheere-Terpstra Statistic [std. J-T static] for trend =0.488, <i>P</i>&lt;0.001 and std. J-T static=3.265, <i>P</i>=0.001, respectively). <h3>Conclusions:</h3> This study provides prevalence estimates of RBD and its possible prodromal conditions based on a structured telephone-interview and RWA measurement on PSG from the general population.

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