A Comprehensive, Multimodal Characterization of Prodromal PD in Subjects With RBD

Comprehensive characterization of early-stage Parkinson's disease in patients with REM sleep behavior disorder

Parkinson's disease (PD) is the fastest-growing neurodegenerative disorder worldwide, significantly affecting quality of life and causing substantial social and economic burdens. Currently, treatments for Parkinson's disease primarily manage symptoms through medication and lifestyle changes but cannot stop disease progression. By the time Parkinson's disease is diagnosed, substantial nerve-cell loss has already occurred in specific brain areas. Identifying early signs of PD before symptoms fully develop is essential for improving future treatment strategies.

This research project aims to deeply understand the earliest stages of Parkinson's disease by studying patients with REM sleep behavior disorder (RBD). RBD is a condition characterized by unusual movements or behaviors during dream sleep, caused by nerve-cell loss in the brainstem. Importantly, more than 80% of individuals with RBD eventually develop Parkinson's disease or related conditions, such as Dementia with Lewy Bodies or Multiple System Atrophy.

Study Goals:

Our study will examine multiple potential biomarkers (measurable indicators) that could help identify early stages of Parkinson's disease. These include:

1. Brain structure changes: The Investigators will use advanced imaging methods (7-Tesla MRI) to closely examine specific brain regions known to be affected early in Parkinson's disease, particularly the substantia nigra and the locus coeruleus (LC). The LC helps regulate sleep and wakefulness, and studies have shown it is damaged in patients with RBD and Parkinson's disease. Additionally, the investigators will use specialized imaging (Pe2i-PET and MIBG-scintigraphy) to measure dopamine availability and changes in heart nerve function. 2. Abnormal protein buildup (ɑ-synuclein): In Parkinson's disease, nerve-cell death is linked to abnormal clumping of a protein called ɑ-synuclein within cells. Detecting this abnormal protein buildup early might help identify who is at risk of developing Parkinson's disease. The investigators aim to explore how levels of ɑ-synuclein aggregation relate to other early signs of the disease. 3. Functional changes in brain and body: Polysomnography, an overnight sleep test recording brain (EEG) and heart (ECG) activity, is the best method for diagnosing RBD. The investigators will also measure brain activity during wakefulness to further understand early changes. 4. Symptoms and physical tests: Participants will undergo thorough clinical assessments, including motor and cognitive tests, as well as tests evaluating autonomic (automatic nervous system) function, such as cardiovascular responses using a tilt-table test.

Together, these extensive assessments will provide a detailed understanding of how Parkinson's disease begins and progresses. This knowledge can greatly improve early diagnosis, allowing earlier and potentially more effective treatments for individuals at high risk.

Study Design:

The investigators will recruit:

* 50 individuals diagnosed with REM sleep behavior disorder * 50 control participants without major psychiatric or neurological disease, matched by age and gender

THe investigation team have a complete, detailed plan and will begin collecting data as soon as ethical approval is granted.

Main Hypotheses:

Although our extensive data will allow many analyses, the investigation team specifically predict:

* Individuals with RBD will show more significant damage in the locus coeruleus compared to controls. * Greater damage in the locus coeruleus will correlate with more severe cognitive issues, sleep problems, and autonomic dysfunction. * Cognitive issues in RBD patients might correlate with specific patterns of damage in different parts of the locus coeruleus. For example, memory problems might be linked to more damage in the front (rostral) part of this region.

Impact:

This study will significantly enhance early detection of Parkinson's disease, paving the way for personalized medical approaches and potentially more effective treatments. Conducted by a multidisciplinary team of experts in brain imaging, sleep medicine, autonomic function, and protein aggregation, this research supports Denmark's leadership in precision clinical imaging and aligns closely with hospital research strategies aimed at understanding and treating chronic diseases. Ultimately, our goal is to improve personalized patient care for Parkinson's disease in the future.