Executive dysfunction is the earliest sign of preclinical Alzheimer’s disease detected by regional Ab‐PET SUVr in the precuneus and posterior cingulate cortex
Bibliographic record
Abstract
Abstract Background Amyloid (Aβ) deposition occurs many years or even decades before the appearance of cognitive decline (preclinical Alzheimer’s disease (pAD)). The diagnosis of pAD is based on biomarker positivity using diagnostic tests such as amyloid‐PET that can provide regional quantification of Aβ deposition in the brain. The precuneus and posterior cingulate gyri are thought to represent the earliest brain regions affected by AD pathology. The present study sought to explore the associations of amyloid‐PET standardized uptake value ratio (SUVr) positivity with global, executive, and memory‐specific domain involvement in pAD. Method Ninety‐nine clinically‐normal, aged participants with Montreal Cognitive Assessment (MoCA) scores ≥ 23 that had undergone amyloid‐PET scanning were analyzed. The participants were divided into two groups based on SUVr in the posterior cingulate and precuneus gyri (SUVR≥1.17). Between group differences in MoCA, Trail Making Test (TMT), and California Verbal Learning Test‐II (CVLT‐II) scores were analyzed using two‐sided independent t test. Result The sample included 45 participants in the pAD group and 54 participants in the healthy control group that did not differ in age or education. Statistically significant between group differences were seen for TMT B, TMT B‐A and MoCA (p = 0.006, 0.001 and 0.034, respectively). No significant differences were seen between groups in delayed recall measures on the CVLT‐II. Conclusion While the prevailing view in the field suggests that early memory change is the hallmark of AD, the present data demonstrate that changes in executive function may be the earliest signs of pAD. Ongoing and future efforts at developing more sensitive tests for preclinical executive function deficits may serve as the most sensitive, low cost, non‐invasive clinical biomarkers of pAD.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 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) | 0.002 | 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".