Volumetry of the Olfactory‐Related Structure as a New Biomarker of Individuals at Risk of Alzheimer Disease? Results From the CIMA‐Q Cohort
Bibliographic record
Abstract
Abstract Background Hippocampal and entorhinal atrophies are used as gold‐standard biomarkers of the prodromal stage of Alzheimer's disease (AD). These atrophies are related to episodic memory deficits found in individuals with mild cognitive impairment (MCI). Olfactory deficits have been identified as clinical biomarkers of AD and found in individuals with MCI. Olfactory‐related structures such as the primary olfactory cortex (POC) were found to be atrophied in patients with AD. The aim of this study was to evaluate if the atrophy of hippocampal and entorhinal regions in individuals with MCI was accompanied with the atrophy of the POC regions. Method Using voxel‐based morphometry (VBM), we compared hippocampal, entorhinal and POC’s grey matter volume between a group of 93 participants with memory complaint (mean age: 72.15, SD: 4.74) and a group of 40 patients with MCI (mean age: 72.08, SD: 5.51) from the Consortium for the early identification of Alzheimer's disease–Quebec (CIMA‐Q). VBM analyses were done using the region of interest (ROI) approach with a specific mask combining masks for the hippocampus and the entorhinal cortex from the Neuromorphometrics atlas and a mask for POC structures from Northwestern University (Zhou et al., 2019). Result VBM analysis reveals smaller bilateral grey matter volume within bilateral hippocampus (left peak: MNI ‐32 −10 ‐22, k = 24, T = 3.78, pFWE corr. = 0.033) (right peak: MNI 30 −8 ‐26, k = 111, T = 4.11, pFWE corr. = 0.016) and right POC (peak: MNI 27 0 ‐14, kE = 20, T = 3.71, pFWE corr. = 0.035) in MCI patients compared to the older participants with memory complaints. Conclusion The neurodegeneration of olfactory‐related structures seems to occur in the prodromal stage of AD and atrophy of these structures might represent a way to improve the specificity of preclinical AD if combined with hippocampal atrophy.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".