CSF α-Synuclein Seed Amplification Assay in Patients With Atypical Parkinsonian Disorders
Chloe Anastassiadis, Iván Martínez-Valbuena, Anna Vasilevskaya, Simrika Thapa, Mohsen Hadian, Alonso Morales‐Rivero, Daniela Mora‐Fisher, Cristina Salvo, Foad Taghdiri, Christine Sato, D. González Moreno, Cassandra Jessica Anor, Karen Misquitta, Blas Couto, David F. Tang‐Wai, Anthony E. Lang, Susan H. Fox, Ekaterina Rogaeva, Gábor G. Kovács, Maria Carmela Tartaglia
Abstract
BACKGROUND AND OBJECTIVES: There is no disease-modifying treatment of corticobasal syndrome (CBS) and progressive supranuclear palsy (PSP), 2 disorders characterized by their striking phenotypic, and, in CBS, pathologic heterogeneity. Seed amplification assays (SAAs) could enable the detection of neuropathologic processes, such as α-synuclein (αSyn) copathology, that affect the success of future disease-modifying treatment strategies. The primary objective was to assess possible αSyn copathology in CBS and PSP, as detected in CSF using an αSyn SAA (αSyn-SAA). Secondary objectives were to evaluate the association of αSyn-SAA positivity with other biomarkers including of Alzheimer disease (AD), and with clinical presentation. We hypothesized that αSyn-SAA positivity would be detectable in CBS and PSP and that it would be associated with AD biomarker positivity and β-amyloid (Aβ) 42 levels, neurodegeneration as assessed by neurofilament light chain (NfL) levels, and symptoms associated with synucleinopathies. METHODS: This cross-sectional observational study included patients clinically diagnosed with CBS and PSP who underwent a lumbar puncture between 2012 and 2021 (Toronto Western Hospital, Canada). CSF was tested for αSyn-SAA positivity, AD biomarkers, and NfL levels. Clinical data were derived from medical records. RESULTS: < 0.01). DISCUSSION: We detected a frequency of αSyn-SAA positivity in CBS and PSP in line with pathologic studies, highlighting the usefulness of SAAs for in vivo detection of otherwise undetectable neuropathologic processes. Our results also suggest that AD status (specifically low Aβ42) and older age at onset may contribute to αSyn-SAA positivity. This opens new perspectives for the stratification of patients in clinical trials.