An observational clinical and video-polysomnographic study of the effects of clonazepam in REM sleep behavior disorder.

To analyze the differences in sleep structure and nocturnal motor activity between drug-free REM sleep behavior disorder (RBD) patients and those under therapy with clonazepam, and to evaluate the long-term longitudinal changes under continued therapy with clonazepam. Fifty-seven consecutive iRBD patients were recruited (52 men and 5 women, mean age 68.8±6.03years). Forty-two patients were not taking any medication at the time of the evaluation (iRBD-Clo) while 15 were taking clonazepam (0.5-1mg) at bedtime (iRBD+Clo). The Clinical Global Impression-Severity (CGI-S) scale was obtained. Sleep was video-polysomnographically recorded and the RBD severity scale (RBDSS) obtained. The chin EMG amplitude was quantitatively assessed and the Atonia Index computed. Disease duration was significantly longer in iRBD+Clo patients who also showed a lower rate of stage shifts, higher sleep efficiency and lower percentage of wakefulness after sleep onset and of sleep stage 1, and an increased percentage of sleep stage 2. The longitudinal long-term follow up study in a subgroup of 13 patients showed moderately increased total sleep time, sleep efficiency, sleep stage 2, slow-wave sleep and decreased wakefulness after sleep onset and sleep stage 1, under clonazepam treatment. The CGI scale clearly tended to improve after treatment, but no common trend was evident for RBDSS or Atonia Index. This study provides evidence of important objective effects of clonazepam on NREM sleep in RBD; this data might be very important for the development of new and effective treatments for this condition.