Understanding REM Sleep Behavior Disorder through Functional MRI: A Systematic Review.

Area of Science:

• Neuroscience
• Neurology
• Neuroimaging

Background:

• Rapid eye movement sleep behavior disorder (RBD) is a prodromal marker for synucleinopathies like Parkinson's disease (PD).
• Functional magnetic resonance imaging (fMRI) is sensitive to early neural network alterations in neurodegenerative diseases.

Approach:

• Systematic review of 32 original fMRI studies (2000-2024) on isolated RBD (iRBD) and PD with RBD, adhering to PRISMA guidelines.
• Analysis of functional connectivity changes across brain regions and networks in iRBD and PD patients with RBD compared to controls and PD patients without RBD.

Key Points:

• iRBD patients show widespread functional alterations in brainstem, basal ganglia, and cortical networks compared to healthy controls.
• PD with RBD patients exhibit reduced whole-brain and brainstem connectivity but increased cerebellar and frontal lobe connectivity versus PD without RBD.
• Longitudinal fMRI data indicate that resting-state functional connectivity changes correlate with disease progression.

Conclusions:

• fMRI detects early neurodegenerative signatures in motor and non-motor pathways in RBD.
• fMRI in RBD holds potential for differentiating prodromal PD from prodromal dementia with Lewy bodies.
• fMRI-based measures could serve as outcomes in clinical trials for disease-modifying therapies.