NAPS builds a shared framework for the earliest known stage of synucleinopathy
Isolated or idiopathic rapid eye movement sleep behavior disorder, or iRBD, sits at the center of a major clinical challenge in neurology and sleep medicine. It is a recognized prodromal state for α-synuclein disorders, including Parkinson’s disease, dementia with Lewy bodies, and multiple system atrophy, yet the field has struggled to study it with the consistency needed for therapeutic trials. The North American Prodromal Synucleinopathy, or NAPS, Consortium was created to solve that problem by bringing together academic sleep centers, a harmonized assessment strategy, and a longitudinal observational design aimed at the earliest measurable phase of disease.
The protocol sets out a multi-site effort across nine academic centers in North America. More than 500 individuals with iRBD will be enrolled from existing sleep clinics and followed over time, alongside 60 control participants matched for age, sex, and race. The study is not a treatment trial; it is the infrastructure trial that many disease-modifying programs have needed before they can realistically begin. In a field where progression is slow, phenoconversion is variable, and baseline characterization differs from center to center, standardization may be as important as any biomarker.
A longitudinal cohort built to reduce trial friction
The main obstacle in iRBD research is not identifying risk; it is conducting studies that are large, coherent, and reproducible enough to support intervention testing. Patients with iRBD are often dispersed across sleep centers, assessed with different instruments, and followed with inconsistent schedules. Biomarker work is similarly fragmented, with no single validated measure yet able to define disease burden in a way that can anchor a pivotal prevention trial.
NAPS addresses those bottlenecks directly. Each participant undergoes a standardized clinical battery that spans motor, cognitive, autonomic, psychiatric, sensory, and sleep domains. That breadth matters because iRBD is not simply a parasomnia; it is a window into a neurodegenerative process that can involve multiple systems long before the first parkinsonian motor syndrome appears. The protocol also includes structured diagnostic adjudication, biospecimen collection, and centralized analysis of both polysomnography and neuroimaging data.
The annual follow-up schedule creates a living cohort rather than a static registry. Participants are reassessed each year, and when a person phenoconverts to overt disease, that individual is replaced in the study cohort. This design preserves the longitudinal structure needed to study prodromal change while maintaining the size of the active observational sample. It is a pragmatic choice, especially for a syndrome where conversion to Parkinson’s disease, dementia with Lewy bodies, or multiple system atrophy can occur after years of apparently stable sleep symptoms.
Why iRBD matters for synucleinopathy prevention
The biological rationale for focusing on iRBD is straightforward. In many patients, dream enactment behavior appears years before the classic motor, cognitive, or autonomic features of α-synuclein disease. By the time a clinical diagnosis of Parkinson’s disease or dementia with Lewy bodies is made, much of the underlying neurodegenerative process has already advanced. That is why prodromal cohorts are so important: they offer a chance to identify the disease before major neurologic disability develops.
A cohort like NAPS is designed to make that window usable. The study’s emphasis on harmonized assessments across motor, cognitive, autonomic, psychiatric, sensory, and sleep domains reflects the reality that prodromal synucleinopathy is distributed, not isolated to one system. A patient may have subtle motor slowing, constipation, hyposmia, orthostatic symptoms, mood changes, or cognitive inefficiencies long before a formal diagnosis emerges. Capturing those features in the same way at every site creates a more reliable baseline and improves the interpretability of future interventional studies.
The protocol also recognizes a central limitation in the field: without common methods, it is difficult to compare cohorts, pool data, or define a practical threshold for disease burden. Centralized review of polysomnography and neuroimaging offers one route to greater consistency, especially when those studies are used to support biomarker development or eligibility criteria for neuroprotective trials.
This is the kind of groundwork that determines whether a prevention study can recruit quickly enough, follow patients long enough, and measure change clearly enough to be credible.
Centralized phenotyping and biospecimens are the core assets
The study’s value lies not only in the number of participants, but in the structure of the data collected from each one. Biospecimen collection creates an opportunity for future molecular analyses, while centralized imaging and sleep scoring help eliminate site-to-site drift. The protocol’s design signals a deliberate move away from isolated local datasets toward a coordinated North American resource that can support a range of downstream investigations.
For clinicians, this matters because iRBD is one of the clearest known clinical entry points into synucleinopathy. For investigators, it matters because the field still lacks a validated biomarker that can stand in for disease burden with enough confidence to guide therapeutic decisions. The NAPS framework is built to narrow that gap by linking carefully phenotyped participants to standardized physiologic and imaging data over time.
The consortium also expands geographic reach. By enrolling from established sleep centers across multiple sites, the study aims to reduce the center-specific bias that can distort natural history research. A broader recruitment network should also improve the diversity and representativeness of the cohort, though the protocol itself remains focused on feasibility, consistency, and readiness for trials rather than on proving treatment effect.
What this protocol changes for future trials
The immediate clinical consequence is practical: neuroprotective studies in iRBD will have a stronger platform for enrollment, follow-up, and endpoint development. The protocol is explicitly intended to facilitate trials of therapies designed to delay or prevent progression from iRBD to Parkinson’s disease, dementia with Lewy bodies, or multiple system atrophy. It does not claim to answer whether such therapies work. Instead, it creates the infrastructure needed to test that question properly.
For a prodromal disorder, that distinction is crucial. A prevention study cannot succeed if baseline phenotyping is inconsistent or if progression events are too poorly characterized to compare across sites. NAPS tackles both problems at once by combining annual clinical reassessment, centralized data handling, and a common diagnostic framework across nine academic centers.
The registry is also formally tied to ClinicalTrials.gov under NCT05826457, which places the effort squarely in the realm of organized translational research rather than retrospective observation. The consortium’s work should be read as a readiness platform: a means of making future neuroprotective studies more efficient, better powered, and more comparable from one site to another.
What remains unproven is whether the protocol’s harmonized biomarkers will eventually identify the most informative surrogate measures of disease burden or the best entry criteria for intervention. Until those relationships are established, the field will still be working from a promising but incomplete map of prodromal synucleinopathy.