Idebenone in REM sleep behaviour disorder

The research record

This is the project's file for this landmark, as written and checked. Sources are listed at the end; anything not yet confirmed is marked "Not yet verified".

Who

Ruijin Hospital, Shanghai Jiao Tong University School of Medicine (lead sponsor), with the Second Affiliated Hospital of Soochow University and Union Hospital (Tongji Medical College, Wuhan). One listed site: Ruijin Hospital. Registered as NCT04534023.

What happened

Title: "A Clinical Study of the Efficacy of Idebenone in the Treatment of iRBD Into Synucleinopathies". iRBD means idiopathic (no known cause) REM sleep behaviour disorder, the dream-enacting sleep disorder that often precedes Parkinson's (landmark 221).

• Design. Phase 2, randomised, parallel groups, double-masked, idebenone versus placebo.
• Planned size. The summary says 142 people (71 per arm) treated for 5 years, with follow-up at 1, 3 and 5 years using the MDS-UPDRS (the standard motor rating scale), blood markers, and brain imaging (fMRI or PET-MR).
• Registered size. 28 (actual). The gap between 28 and 142 is unexplained in the record.
• Primary outcome. Five-year conversion rate to a synuclein disease, judged "effective" if the rate falls.
• Dates. Start 31 August 2020. Primary completion estimated 1 September 2026; completion 30 November 2026. Status "active, not recruiting"; the record was last verified in November 2024 and last updated 25 November 2025. No results posted.

Why it moved us toward a cure

It is one of the few registered attempts to treat people before they have motor symptoms, a setting many researchers see as the best chance for a protective drug to work. It tests the idea in landmark 221 that RBD patients can serve as a prevention population. It is a sibling of PRISMS (landmark 225). With 28 people, a 5-year conversion rate cannot be measured reliably, so it is mainly useful as a feasibility signal.

Outcome

Pending, overdue. The registry's estimated primary completion (1 September 2026) has passed with no update to the record (checked 22 Oct 2026; last updated 25 November 2025). The registry still estimates completion on 30 November 2026, which is now the expected date; the true state is unknown.

Sources

• ClinicalTrials.gov NCT04534023
• Not yet verified: why idebenone was chosen (the record states none; I believe it is a lab-made relative of coenzyme Q10, but did not confirm); whether enrolment stopped at 28 or the count is a registry error; whether the trial has ended; any publication. A 2026 Movement Disorders paper (Li et al., DOI 10.1002/mds.70356) reports a 3-year randomised pilot of idebenone in REM sleep behaviour disorder from Ruijin Hospital (27 randomised); we could not confirm it is this registry record (NCT04534023 lists 28), so no result is recorded here.