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54 Sleep spindles as a biomarker for alpha-synucleinopathies in Rapid eye movement (REM) behaviour disorder (RBD)
  1. Eilidh McMillan,
  2. Stevie Williams and
  3. Renata Riha
  1. University of Edinburgh, Edinburgh, UK


Introduction Idiopathic rapid eye movement behaviour disorder (iRBD) is a strong predictor for the development of alpha-synucleinopathies. Electroencephalographic (EEG) oscillations known as sleep spindles are found during non-rapid eye movement sleep. These bursts of neural oscillatory activity are known to decrease in patients with alpha-synucleinopathies. We hypothesized that that sleep spindle density would differ in patients with iRBD with and without an alpha-synucleinopathy.

Methods This was a retrospective cohort study comprised of sixty male participants, all of whom were diagnosed with RBD. Sleep spindles were manually identified by an experienced technologist at a central scalp location (C3-A2) in 20 patients with iRBD who converted to an alpha-synucleinopathy, 20 age-matched patients with secondary RBD and 20 patients with a diagnosis of iRBD who had not converted.

Results Patients who phenoconverted showed a significant decrease in sleep spindle activity compared to patients with secondary RBD (p<0.05) at time of diagnosis. Spindle density was lower in patients who had phenoconverted. Sleep spindle density reduction was significant in patients with PD; there were too few patients with MSA and DLB to determine differences in spindle density counts.

Discussion This is the first study to look into multiple alpha-synucleinopathies to investigate sleep spindle density changes. As a statistical significance was found between the spindle density of patients who had gone on to develop a neurodegenerative disorder and those who had secondary RBD, when examining spindle density in the second half of the night (p=0.026) (figure 1). It follows that sleep spindle density may have the potential to be a prodromal marker for phenoconversion and underlying alterations in sleep networks that lead to a clinical diagnosis of an alpha-synucleinopathy.

Abstract 54 Figure 1

Sleep spindle density. A) The average spindle density per minute in each block of NREM throughout the night‘*’=p<0.05(One-way ANOVA and post-hoc Tukey’s test)Abbreviations: SS/min=Sleep spindles per minutes. Error bars show a 95% confidence interval

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