Sleep Disorders in Machado–Joseph Disease: Frequency, Discriminative Thresholds, Predictive Values, and Correlation with Ataxia-Related Motor and Non-Motor Features

Sleep disorders are common complaints in patients with neurodegenerative diseases such as spinocerebellar ataxia type 3 (SCA3) or Machado–Joseph disease (MJD)—SCA3/MJD. We evaluated the frequency of sleep disorders in SCA3/MJD patients against controls matched by age and gender, and correlated data with demographic and clinical variables. The main sleep disorders evaluated were rapid eye movement (REM) sleep behavior disorder (RBD), restless leg syndrome (RLS), and excessive daytime sleepiness (EDS). We recruited 40 patients with clinical and molecular-proven SCA3/MJD and 38 controls. We used the following clinical scales to evaluate our primary outcome measures: RBD Screening Questionnaire, International RLS Rating Scale, and Epworth Sleepiness Scale. To evaluate ataxia-related motor and non-motor features, we applied the International Cooperative Ataxia Rating Scale, the Scale for the Assessment and Rating of Ataxia, and the Unified Parkinson’s Disease Rating Scale part III. Psychiatric manifestations were tested with the Hamilton Anxiety Scale, and Beck Depression Inventory. The frequency of RBD and RLS were significantly higher in the SCA3/MJD group than in the control group (p < 0.001). There was no difference between both groups with regard to EDS. The accuracy of RDBSQ to discriminate between cases and controls was considered the best area under the ROC curve (0.86). Within-SCA3/MJD group analysis showed that anxiety and depression were significantly correlated with RDB, but not with RLS. Additionally, depression was considered the best predictive clinical feature for RDB and EDS.