Patient groups

Initial phase of CSF RT‐QuIC development was carried out on 99 CSF samples obtained from the OPTIMA cohort (Oxford Project to Investigate Memory and Ageing) with clinically and neuropathologically confirmed diagnosis of pure DLB (n = 12), PD (n = 2), progressive supranuclear palsy (PSP) (n = 2), corticobasal degeneration (n = 3), DLB with AD pathology (n = 17), AD with incidental LBs (n = 13), pure AD (n = 30), and controls (n = 20). OPTIMA initiated in 1988, is a prospective, longitudinal clinico‐pathological study of dementia and aging including CSF collection at multiple time points during clinical follow‐up. All clinical and pathological protocols have been described in detail13 and were approved by the local ethics committee and participants provided informed consent prior to enrollment.

The validation phase of RT‐QuIC was carried out on CSF samples (20 PD, 15 controls, and 3 at‐risk) obtained from the Oxford Discovery cohort (http://opdc.medsci.ox.ac.uk) which is one of the largest, clinically best‐characterized longitudinal PD cohorts to date. Full clinical details of this cohort have been described previously.14 In brief, patients with idiopathic PD diagnosed within 3.5 years according to UK PD Society Brain Bank diagnostic criteria15 were recruited between September 2010 and September 2014 from a 2.9 million population (ethics study 10/H0505/71). Mean disease duration among 20 PD patients was 1.6 ± 1.1 years (range 0.1–3.2 years) and Hoehn and Yahr stage 1.9 ± 0.4 (range: 1–3, maximum possible score 5). The control population was recruited from spouses and friends of patients taking part in the study, as well as the general public. The at‐risk group comprised patients with REM sleep behavior confirmed on overnight polysomnography,16 80% of which have shown to develop Lewy body disorder over time.17 Demographic information is given in Table 1.

Patient demographic information for the Optima and Discovery patients investigated