O2‐02‐01: Early‐life linguistic ability, late‐life pathology and asymptomatic Alzheimer's disease: Findings from the Nun Study
Bibliographic record
Abstract
The observation that not all who meet neuropathologic criteria for Alzheimer's disease (AD) are demented has stimulated interest in the concept of brain reserve. Early-life measures reflecting reserve capacity, such as linguistic ability, may distinguish those who resist clinical expression of AD (asymptomatic AD) from those who become demented, but these measures also act in the context of late-life predictors of dementia, such as brain infarcts and atrophy. The Nun Study is a longitudinal study of aging in 678 participants 75+ years; 180 wrote early-life autobiographies and 56 of these met CERAD neuropathologic criteria for AD (29 demented, 27 not demented). Autobiographies were analyzed for idea density and grammatical complexity, with ranked scores categorized as high (top three quartiles) or low (bottom quartile). Cerebral cortical atrophy, large or lacunar brain infarcts, and neuropathologic diagnosis of AD were determined by gross and microscopic postmortem examinations. In logistic regression models adjusted for age at death, education and APOE, asymptomatic AD was six times more likely in individuals with high idea density (Odds ratio [OR]=6.77; 95% confidence interval [CI]=1.23-37.31) and eight times more likely in those with high grammatical complexity (OR=7.97; 95% CI=1.81-35.16) compared with individuals with low idea density and grammatical complexity, respectively. The association of linguistic ability with asymptomatic AD was modified by the presence of brain infarcts and atrophy, and remained significant only in individuals with these late-life pathologies. Linguistic ability in early life significantly predicts likelihood of asymptomatic AD in late life, with its strongest impact in those with brain infarcts or atrophy. Elucidation of the association and interactions of predictors with asymptomatic AD may provide insight into mechanisms of cognitive reserve and strategies to maintain cognition in late life.
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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 | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| 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".