Olfaction in patients with isolated REM sleep behavior disorder who eventually develop multiple system atrophy
Bibliographic record
Abstract
Olfactory impairment is common in patients with idiopathic rapid eye movement sleep behavior disorder (iRBD) [1]. iRBD is an early phase alpha-synucleinopathy, as most of these patients convert over time to Parkinson’s disease (PD), dementia with Lewy bodies (DLB) or, more rarely, multiple system atrophy (MSA) [2]. Olfactory dysfunction is frequent in PD3 and in DLB, whereas in MSA olfaction is usually not impaired [3, 4]. Therefore, the aim of this retrospective study was to investigate whether patients with initially iRBD who eventually converted into MSA had hyposmia or were normosmic before conversion. Data were retrospectively collected among the members of the International RBD Study Group (IRBDSG). The IRBDSG comprises 24 centers following a total of 1280 RBD patients [1]. All patients with iRBD who eventually developed MSA and underwent olfactory test before conversion were included in this study. Demographic and clinical data, as well as information about olfactory function, were collected. As different olfactory tests were used, for data analysis scores were converted to brief smell identification test (B-SIT) scores using published equating scores [5]. Among all centers, 16 patients with initially iRBD eventually developed MSA after a mean follow-up time of 4.6 years [1]. Twelve patients with initially iRBD underwent olfactory test before conversion to MSA and could be included in this study. The mean age was 68 ± 9 years. Seven patients (58.3 %) were female, and five (41.7%) were male. Age at diagnosis of iRBD was 60 ± 8 years, and age at conversion to MSA 64 ± 9 years, with a time from iRBD diagnosis to conversion of 4 ± 3 years. Olfactory testing before conversion was normal in 6/12 (50 %) and showed hyposmia in 6/12 (50 %) of the participants. The frequency of olfactory dysfunction in our cohort of iRBD who eventually developed MSA (50 %) is slightly higher than the reported frequency in the elderly population (25%–30%) [3, 6], but much lower than the frequency of hyposmia/anosmia in patients with PD (up to 100%) [3, 4]. Interestingly, olfactory function has been suggested to predict phenoconversion in patients initially presenting with pure autonomic failure (PAF). In a prospective large cohort of 100 patients with PAF, those who phenoconverted to MSA had preserved olfaction, whereas those who phenoconverted to PD or DLB had decreased olfaction [7]. Based on our preliminary observations in iRBD, we speculate similarly that normosmia in these patients might be considered predictive of conversion to MSA. To confirm this hypothesis, prospective studies with larger sample size and including also matched controls as well as patients who eventually converted to PD or DLB are needed. The authors confirm that patient consent was not required for this work, as this is a retrospective study. We confirm that we have read the Journal’s position on issues involved in ethical publication and affirm that this work is consistent with those guidelines. A.S.: research project organization and execution; statistical analysis design and execution; writing of the first draft of the manuscript. L.F.-S.: review and critique of the manuscript. R.B.P.: review and critique of the manuscript. A.I.: review and critique of the manuscript. A.V.: research project organization; review and critique of the manuscript. B.H.: research project organization and execution; review and critique of the manuscript. G.K.W.: research project conception and organization; statistical analysis review and critique; review and critique of the manuscript. Conflict of interest statement. None declared.
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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 | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".