Objective: to assess the correlations between the severity of RSWA and cognitive functions in patients with RBD, both isolated (iRBD) and associated to Parkinson’s Disease (PDRBD).

Background: RBD might represent a prodromal markers of Parkinson’s disease and other alpha-synucleinopathies(1) Moreover, RBD in PD may be associated with a malignant phenotype with an increased risk for dementia.(2)

Method: Sixty-seven RBD (M=50, mean age 69.5±8.0yrs, including 25PDRBD and 42iRBD) were enrolled. RBD diagnosis was made according to standard criteria.(3)Severity of RSWA was quantified according to the Montreal (%tonic and phasic chin EMG activity), and the SINBAR scoring method (%any, either tonic or phasic chin EMG activity combined with bilateral upper limbs EMG activity).(4,5)All patients underwent a comprehensive neuropsychological assessment. Correlations between RSWA measures and neuropsychological data were assessed by Pearson.

Results: Severity of both tonic and “any” components of RSWA showed significant positive correlation with inhibition and selective attention (r=0.332,p=0.023), visuo-constructional abilities (r=-0.330,p=0.022), phonemic fluency (r=0.459,p=0.001), and significant negative correlation with visuospatial functions(r=-0.519,p=0.001). Moreover, severity of phasic component of RSWA showed significant negative correlations with global cognitive functions (r=-0.370, p=0.009), long-term verbal memory (r=-0.439,p=0,002), visuoconstructional abilities (r=-0.586,p<0.000), semantic and phonemic fluency (r=-0.340,p=0.018), visuospatial functions (r=-0.462,p=0.001), and significant positive correlation with inhibition and selective attention(r= 0.295,p=0.047), working memory (r=0.574,p=>0.000). Moreover, a significant correlation was found between severity, of both phasic, tonic and any components of RSWA and the total score of the Hospital Anxiety and Depression Scale (r=0.360,p=0.034).

Conclusion: The severity of RSWA, especially its component related to phasic EMG activity, correlates with cognitive functions, particularly with visuospatial abilities and with the executive functions, in a sample of RBD patients. Furthermore, severity of phasic components of RSWA showed significant correlation with anxiety and depression in these patients. Further studies will assess the relationships between RSWA and cognitive functions in each of the two RBD populations (iRBD and PDRBD).

References: 1. Postuma RB. Prodromal Parkinson’s disease–using REM sleep behavior disorder as a window. Parkinsonism Relat Disord. 2014 Jan;20 Suppl 1:S1-4. 2. Fereshtehnejad S-M, Romenets SR, Anang JBM, Latreille V, Gagnon J-F, Postuma RB. New Clinical Subtypes of Parkinson Disease and Their Longitudinal Progression: A Prospective Cohort Comparison With Other Phenotypes. JAMA Neurol. 2015 Aug 1;72(8):863. 3. ICSD-3 Online Version – American Academy of Sleep Medicine (AASM) [Internet]. AASM. 2015 [cited 2015 Jan 10]. Available from: http://www.aasmnet.org/store/product.aspx?pid=849

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MDS Abstracts - https://www.mdsabstracts.org/abstract/severity-of-rem-sleep-without-atonia-rswa-correlates-with-cognitive-functions-in-patients-with-rem-sleep-behaviour-disorder-rbd/