REM sleep behavior disorder: relation between aggressiveness and emotions expressed in dream enactment and cognitive and anxiety/depression status

Aggressiveness and negative emotions in dreams reports of patients with alfa-synucleinopathies have been associated with cognitive dysfunction. Observation of dream enactment episodes could be a more precise method to capture dream content in patients with REM sleep behavior disorder (RBD). Our objective was to assess the relation between aggressive and emotional dream enactment episodes in patients with RBD and cognition and depression/anxiety. Motor events (ME) during REM sleep were classified by visual inspection of video-PSG files. Cognition and anxiety/depression were assessed with MoCA and the Hospital Anxiety and Depression Scale (HADS), respectively. Multivariate regression analysis was performed, with MoCA or HADS scores as predictors, age and DED as co-variates and aggressive, negative and positive ME frequency (raw values, per total and per complex indexes) as the dependent variable. We included 15 patients with isolated RBD and 12 and 4 with RBD associated with Parkinson's disease and Dementia with Lewy Bodies, respectively. They presented a total of 873 ME. There was a significant positive association between HADS score and violent/complex and negative emotion/complex indexes. There was a significant positive association between MoCA score and violent/complex index. A significant correlation between depression/anxiety severity and negative emotion and aggression ME frequency agrees with the dream continuity hypothesis and suggests that REM sleep acts as a regulator of emotional experience. Patients with a higher prevalence of aggressive ME had higher scores in cognitive testing, suggesting that the elaboration of these complex movements could depend on the integrity of cognitive functions.