The amnestic syndrome of hippocampal type is frequent in patients without hippocampal atrophy in a memory clinic population
Bibliographic record
Abstract
Abstract Background Since 2011, diagnostic criteria for Alzheimer’s Disease have led to the introduction of biomarkers. Hippocampal atrophy, either volumetric or visually‐rated is arguably the most widely available biomarker of neurodegeneration. An association with a specific type of amnestic disorder has been claimed, but the clinical validity of this concept remains to be established in unselected patient populations. This problem is important as the amnestic syndrome of the hippocampal type is theoretically a key element in the diagnosis of the most common clinical syndrome of Alzheimer’s disease. Our objective was to determine the correlation between the amnestic syndrome of hippocampal type and hippocampal atrophy. Method This is a retrospective study of 274 consecutive patients who were assessed in the Memory Clinic between 01/2014 and 11/2018. Verbal memory was assessed with the Free and Cued Selective Reminding Test (FCSRT) and the Montreal Cognitive Assessment Memory Index Score. Brain imaging was performed within six months of the neuropsycholgical assessment and hippocampal atrophy was estimated using the Scheltens Scale, adjusted for age. Result The Scheltens scale had a moderate correlation with FCSRT free recall (Pearson correlation = ‐0,425, p<0,001) and weak correlation with FCSRT Cueing index (Pearson correlation = ‐ 0,293, p< 0,001). However, 34% of our cohort (n=93) had an abnormal FCSRT Cueing index (< = 71%), but a normal Scheltens score. As for the MoCA‐MIS, 26% of our cohort (n=57) had an abnormal score (< = 7), but a normal Scheltens score. Conclusion A large subgroup of our patients demonstrate an amnestic syndrome of the hippocampal type, without showing hippocampal atrophy on routine brain imaging. Our results show the limits of equating hippocampal atrophy with the particular profile of amnesia that does not improve with cueing. The claimed specificity of this type of cognitive deficit in the differential diagnosis of dementia needs to be re‐assessed.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".