Persistent Hyposmia as Surrogate for α-Synuclein-Linked Brain Pathology
Bibliographic record
Abstract
ABSTRACT Impaired olfaction can be associated with neurodegenerative disorders. We examined odor identification in newly diagnosed patients with parkinsonism and those at increased risk, measured olfactory performances longitudinally, and juxtaposed results to cerebrospinal fluid (CSF) values. Using Sniffin’-Sticks-Identification Tests (SST-ID), we examined 312 age-matched individuals at a German center, including: 126 with Parkinson disease (PD), 109 healthy controls, 25 with other neurodegenerative disorders and 52 with a REM-sleep behavior disorder (RBD). As expected, PD patients had significantly lower SST-ID scores than controls. Scent identification by subjects with other neurodegenerative diseases fell between those with PD and healthy individuals. Those with isolated RBD, who subsequently converted to PD or dementia, had lower baseline scores than non-converters. When monitoring olfaction in participants up to a decade, we saw small group differences in progression rates for hyposmia. However, these variations were insignificant after controlling for age, sex and length of intervals between testing. When analyzing participants’ sense of smell versus several CSF biomarkers linked to neurodegeneration, we found no correlation with SST-ID scores. However, the means for normalized concentrations of α-synuclein, total tau, phosphorylated tau and amyloid-β peptide 42 were reduced in PD. We also identified significant age- and sex-linked differences in CSF values. Finally, we compared olfaction to the results of a validated α-synuclein ‘Seed Amplification Assay’ (SAA) using CSF. We found that hyposmia strongly correlated with a positive CSF α-synuclein SAA-test. We conclude that chronically impaired olfaction in older adults is strongly associated with a positive α-synuclein SAA-test from CSF but not with the concentrations of several, neuropathologically relevant CSF markers. We posit that simple-to-administer, quantitative smell tests could serve as inexpensive screening tools in future population studies for the identification of α-synuclein-related brain disorders, including Parkinson’s during its premotor phase.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".