To analyze the timeline, incidence, and survival of REM sleep-behavior disorder (RBD) in patients who developed alpha-synucleinopathies compared to age and sex-matched controls in an incident-cohort study.

We used an incident cohort study of alpha-synucleinopathies 1991-2010 among Olmsted County, MN residents. A movement-disorder specialist reviewed medical records to confirm diagnoses. REM sleep-behavior disorder was diagnosed by reported dream-enactment symptoms (Probable RBD) or polysomnography.  Probable RBD and polysomnography-confirmed RBD were analyzed singularly and combined.

Among the 444 incident cases of an alpha-synucleinopathy, 86 were clinically diagnosed with RBD (19.8%) including 30 (35%) by polysomnography and 56 (65%) as probable. The frequency of RBD within our cohort of alpha-synucleinopathy patients was 3.4%. The frequency of RBD increased to 23.8% after 15 disease years, with an overall incidence of 2.5 cases per 100 person years. The odds of developing RBD was 53 times greater in alpha-synucleinopathy patients than controls (OR=53.1, 95% CI: 13.0- 217.2, p<.0001), higher in DLB compared to PD, (OR=2.57, 95% CI: 1.50–4.40, p=.0004), higher in men compared to women with PD/DLB/PDD (OR = 3.70, 95% CI: 2.07–6.62, p<.0001), but was not associated with mortality. Conversely, the odds of a PDD patient being diagnosed with RBD were 82.6% lower than a PD patients (OR = 0.17, 95% CI: 0.04 – 0.73, p = .008). Median symptom onset of RBD occurred 0.7 years following PD diagnosis (IQR= -3.3 – 5.4). In DLB patients the median RBD symptom onset occurred 3.8 years prior to the diagnosis (IQR=-7.1 — -0.4).

The odds of developing RBD were 53 times greater in alpha-synucleinopathy patients compared to controls. Patients diagnosed with DLB were more likely to develop RBD compared to patients diagnosed with PDD.