Self-testing for symptoms and signs of prodromal alpha-synucleinopathies: results from the Tasmanian ISLAND Sleep Study

Isolated rapid eye movement (REM) sleep behavior disorder (iRBD) may occur at least 10 years before a clinical diagnosis of an α-synucleinopathy, such as dementia with Lewy bodies (DLB), Parkinson's disease (PD) or multiple system atrophy (MSA). The extent to which people with iRBD manifest subtle features of these conditions is an area of active research and whether these changes can be measured remotely in the community is an important aim. Better characterisation may aid early detection and monitoring for people at risk of neurodegeneration. The aim of this study was to investigate remote tests of subjective and objective features of α-synuclein-related conditions in probable iRBD (pRBD). We hypothesised that α-synuclein-related symptoms and signs would be more frequent in pRBD than healthy controls. 2,891 participants aged 50 + from the Tasmanian ISLAND Sleep Study completed the REM Sleep Behavior Disorder Single-Question Screen (RBD1Q), and several online questionnaires and unsupervised objective assessments of motor, cognitive and olfactory function. People with pRBD (n = 267; mean (SD) age 63 (7.6) years; 53% female) reported more α-synuclein-related features than controls (n = 2,624; mean (SD) age 64 (7.7) years; 75% female), especially orthostatic intolerance, neuropathic pain, falls, olfactory impairment and hand motor dysfunction. These results show that people with pRBD exhibit a range of symptoms and signs of α-synuclein-related conditions that can be measured using remote (online and postal) assessment tools. Remote monitoring in the community may aid early detection of progression to DLB, PD and MSA and facilitate enrolment into clinical trials.