Clinical and Imaging Characteristics of Parkinson's Disease with Negative Alpha‐Synuclein Seed Amplification Assay

Key Points

Participants with negative alpha-synuclein assay have lower hyposmia rates, indicating potential variations in the disease presentation.
About 14% of SAA- participants experienced a change in diagnosis during the study, highlighting diagnostic uncertainty.
Participants were assessed on clinical characteristics like hyposmia and brain imaging for subcortical atrophy.
Findings suggest further investigation into the implications of subcortical brain atrophy for diagnosis and treatment.

Abstract

At baseline, SAA- sPD PPMI participants have a substantially lower rate of hyposmia, but otherwise cannot be readily distinguished from SAA+ participants based on clinical characteristics. However, SAA- participants have a greater degree of subcortical brain atrophy, and approximately one out of seven SAA- participants received a change in diagnosis. © 2026 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Clinical and Imaging Characteristics of Parkinson's Disease with Negative Alpha‐Synuclein Seed Amplification Assay

Key Points

Abstract

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