Progression of two Progressive Supranuclear Palsy phenotypes with comparable initial disability.

Area of Science:

• Neuroscience
• Neurology
• Clinical Trials

Background:

• Progressive Supranuclear Palsy (PSP) is a rare neurodegenerative disease with distinct phenotypes.
• Accurate assessment of disease progression is vital for therapeutic trial design and patient stratification.
• Phenotypic differences, such as PSP-Parkinsonism and PSP-Richardson syndrome, may influence disease trajectory.

Purpose of the Study:

• To compare the disease progression rates between PSP-Parkinsonism and PSP-Richardson syndrome phenotypes.
• To determine if PSP phenotype is a significant predictor of disease progression in clinical trials.
• To inform patient selection criteria for future therapeutic interventions in PSP.

Main Methods:

• A cohort of 138 patients (56 PSP-Parkinsonism, 82 PSP-Richardson syndrome) from the TAUROS trial were analyzed.
• Patients were followed for up to 60 weeks with similar baseline clinical severity.
• Disease progression was assessed using the PSP Rating Scale and secondary outcome measures (e.g., Dementia Rating Scale-2).

Main Results:

• PSP-Richardson syndrome patients exhibited significantly faster disease progression compared to PSP-Parkinsonism patients.
• This difference was evident across primary and key secondary outcome measures.
• PSP phenotype emerged as the strongest predictor of disease progression, even when controlling for baseline symptom duration.

Conclusions:

• PSP-Richardson syndrome is associated with a more rapid disease course than PSP-Parkinsonism.
• Future PSP clinical trials should stratify patients by phenotype to ensure population homogeneity.
• Lumping distinct PSP phenotypes in trials, despite similar baseline severity, may introduce bias and reduce statistical power.