0722 NEURODEGENERATIVE BIOMARKER FREQUENCY IN IDIOPATHIC REM SLEEP BEHAVIOR DISORDER

Abstract

The majority of patients with idiopathic REM sleep behavior disorder (iRBD) are thought to have prodromal synucleinopathy. 25–60% of iRBD patients have probable neurodegenerative biomarkers such as olfactory, orthostatic blood pressure, cognitive, or motor function impairments. We aimed to describe frequencies of neurodegenerative biomarkers in the Mayo Clinic iRBD prospective registry cohort. We included adults diagnosed with iRBD by ICSD-3 criteria, and excluded symptomatic RBD patients (i.e., diagnosis of mild cognitive impairment, dementia with Lewy bodies, Parkinson disease, or multiple system atrophy). We considered clinical neurodegenerative biomarker measures as abnormal when subjects met age-gender defined cut-offs for the brief Smell Identification Test (BSIT) and neurocognitive assessments (Montreal Cognitive Assessment (MOCA), “Kokmen” Short Test of Mental Status (STMS) and King-Devick Test (KDT)), orthostatic systolic blood pressure (SBP) drop >10 mm Hg, or timed up and go (TUG) speed > 7.5 seconds. 38 iRBD subjects participated. Mean age was 65.4 (range 21 - 84) years, and 12 (31%) were women. Duration of dream enactment was 11+/-16 years. 18 (47%) were receiving antidepressant medications. Mean (range) measure scores were: BSIT 8.8 (4–12); MOCA, 26.2 (20–30); STMS, 34.3 (30–38); KD, 60.2 (39–125.6); SBP drop, 14.64 (1–49); and TUG, 8.5 (5.3–13.8) seconds. The number (%) with abnormal biomarker measures were: BSIT, 6 (16%); MoCA, 6 (16%); STMS, 0%; KD, 12 (32%); SBP drop, 15 (41%); and TUG, 11 (31%). Overall, 31 (82%) had one or more clinical neurodegenerative biomarkers at baseline, and 20 (52%) had two or more biomarkers at baseline. Antidepressant medication was not associated with abnormality on any of the measures. 82% of iRBD patients had at least one neurodegenerative biomarker present, suggesting that iRBD is a prodromal synucleinopathy. Further longitudinal analyses of this cohort compared to age-gender matched control subjects is planned. Mayo Clinic CCaTS.