Skip to content

Journal · Sleep

In Parkinson’s, the REM Sleep Disorder Is the Earliest Signal of Cognitive Decline.

In de novo Parkinson's, REM sleep behaviour disorder accelerates cognitive decline across all domains.

Updated October 2, 2026

The PPMI Cohort Study (2024) analysed de novo Parkinson's patients, assessing the presence of REM sleep behaviour disorder (pRBD) and its impact on cognitive decline over time.

Bedroom of an Engadine chalet just before dawn: cold bluish light from the window, pale linen sheets, a smart ring and watch resting on the nightstand; no faces.

REM sleep behaviour disorder (pRBD)

In normal conditions, muscles are paralysed during REM. In pRBD, this paralysis is absent — the patient physically acts out dream content.

Macro detail of a wearable ring and a smartwatch recording sleep phases in low light; night-blue tones, soft reflections; no faces.

pRBD is one of the most powerful neurodegeneration predictors, often present years before diagnosis.

The PPMI Cohort data

Luminous chart of REM and deep-sleep phases projected on the dark wall of a premium clinical room; soft light, order; no faces.

De novo Parkinson's patients with pRBD show faster decline in global cognition and all cognitive domains: verbal memory, visuospatial ability, executive function, language and processing speed.

Implications for early diagnosis

Chalet window at dawn framing the snowy Engadine peaks seen from an unmade bed; cold natural light, stillness; no faces.

pRBD identified early allows activation of intensive neurological monitoring, evaluation of neuroprotective therapies, and cognitive compensation interventions before decline becomes significant.

Silent corridor of an Alpine clinic at dawn, warm materials (wood and stone) and soft light; a mood of clinical calm; no faces.

The Digital Twin as a neurological sentinel

Wearables with advanced accelerometers can detect abnormal movements during REM as an indirect pRBD signal. The Digital Twin integrates these signals into the neurological risk profile.

Bedroom of an Engadine chalet just before dawn: cold bluish light from the window, pale linen sheets, a smart ring and watch resting on the nightstand; no faces.

PPMI Cohort Study — PubMed (2024) — https://pubmed.ncbi.nlm.nih.gov/38764318/ · pubmed.ncbi.nlm.nih.gov

On the same topic

All the research in the Journal →