Eye tracking identifies biomarkers in α-synucleinopathies versus progressive supranuclear palsy

Area of Science:

• Neuroscience
• Ophthalmology
• Neurology

Background:

• Alpha-synucleinopathies (αSYN) like Parkinson's disease (PD) and Multiple System Atrophy (MSA) are neurodegenerative disorders.
• Progressive supranuclear palsy (PSP) is a distinct tauopathy.
• Rapid-eye-movement sleep behavior disorder (RBD) is a prodromal stage of αSYN.

Purpose of the Study:

• To compare saccade and pupil abnormalities in αSYN (PD, MSA) and PSP patients.
• To determine if RBD patients exhibit early abnormal eye responses indicative of future PD or MSA risk.

Main Methods:

• A video-based eye-tracking task (Free Viewing) was used.
• Saccade and pupil behaviors were measured in 90 αSYN patients (46 RBD, 27 PD, 17 MSA), 10 PSP patients, and 132 healthy controls (CTRL).

Main Results:

• All patient groups exhibited reduced macro-saccades and altered saccade responses post-stimulus compared to controls.
• RBD patients showed distinct, less pronounced saccade abnormalities than PD and MSA patients.
• PSP patients displayed vertical gaze palsy and altered pupil responses, differentiating them from αSYN.

Conclusions:

• RBD patients present with early saccade abnormalities, suggesting a preclinical marker for αSYN.
• Vertical gaze palsy and pupil control differences distinguish PSP from αSYN, aiding in differential diagnosis.