Real-World Use of Alpha-Synuclein Seeding Amplification Assay in a Behavioral Neurology Clinic
David Fischer1, Tara Ellingson1, Bruce Miller1, Lawren VandeVrede1
1Memory and Aging Center, Neurology, UCSF
Objective:
To characterize use and impact on clinical decision-making of the alpha-synuclein seeding amplification assay (SAA) in a tertiary behavioral neurology clinic.
Background:
The cerebrospinal fluid (CSF) SAA is a new marker with high specificity for Lewy body disease (LBD) in well-defined research cohorts, but real-world use data are sparse.
Design/Methods:
This is a retrospective cohort of all cases who had the SAA test (SynTap, Amprion) performed at our behavioral neurology clinic. Medical records were reviewed for diagnosis, clinical syndrome/affected cognitive domain(s), cognitive tests, presence of core LBD features and other symptoms, MRI, PET and SPECT imaging, Alzheimer’s disease biofluid markers, and clinical decisions made following the SAA result.
Results:
In our first year of use, the SAA was performed for 21 patients. Most were men (76%). Patients at time of testing were between 53-86 years old (mean 74). Mild cognitive impairment was the most common diagnosis (71%) followed by dementia (19%) and subjective cognitive impairment or normal (9.5%). The SAA was abnormal in 9 patients (43%). The p(181)-tau/amyloid-beta(42) ratio was abnormal in 44% of SAA-positive cases and in 45% of SAA-negative cases. In SAA-positive cases, 5 met the core features from McKeith et al. for probable and 2 for possible LBD; in SAA-negative cases, none were probable and 7 were possible LBD. Of the cohort, 17 had questionable or mild motor parkinsonism. Clinical syndromes varied and included amnestic, multidomain (2/6 positive), non-amnestic, dysexecutive and behavioral (0/5), logopenic primary progressive aphasia (1/1), corticobasal syndrome (1/1), behavioral variant frontotemporal dementia (0/1), multiple system atrophy (0/1), and Parkinson’s disease (0/1); there were no purely amnestic patients tested. Subsequent clinical decisions included additional diagnostic tests and medication changes (lecanemab included).
Conclusions:
The SAA adds diagnostic information in early-stage, heterogeneous clinical presentations and may alter clinical decisions.
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