P3‐033: Physical exercise differentially moderates cognitive decline trajectories in incident dementia and normal aging
Bibliographic record
Abstract
A mentally and physically active lifestyle is a known protective factor against dementia. Education and leisure activities have been shown to delay the onset of accelerated cognitive decline in Alzheimer disease (AD), but it has yet to be determined whether physical exercise similarly delays the clinical expression of AD. We employed data from the Canadian Study of Health and Aging (CSHA) to determine whether physical exercise moderates cognitive decline trajectories in incident AD. The CSHA included three waves: CSHA-1(1991-1992), CSHA-2 (1996-1997) and CSHA-3 (2001-2002). This study included participants who a) completed a Risk Factor Questionnaire (RFQ) and a physician's examination at CSHA-1 and were determined to be nondemented, b) were diagnosed with AD at CSHA-2 or CSHA-3 and c) underwent neuropsychological assessment in at least one of the three waves of the CSHA. Multilevel analyses were used to model change in neuropsychological test performance as a function of self-reported engagement in regular physical exercise documented in the RFQ. Education was included as a covariate. 217 cases of incident AD met criteria for inclusion. We found no effect of physical exercise in this sample. To examine whether these null findings were specific to incident dementia, we re-specified our models to include only those who remained nondemented at CSHA-2 and CSHA-3 (n = 888). Here we found physical exercise to delay decline on the total recall score of the Buschke Cued Recall test (p < 0.05). Given the sample size discrepancy between AD cases and those who remained nondemented, we randomly generated a subsample of 217 nondemented participants to determine whether exercise would moderate cognitive performance in a sample of equal size to the incident AD group. Results again demonstrated a significant effect of physical exercise on total recall of the Buschke Cued Recall test (p < 0.05). We found protective effects of regular physical exercise on cognitive functioning to be specific to participants who remained nondemented through the 10-year course of the CSHA. The differential importance of physical exercise for predicting decline in the non-demented, but not those who developed AD, suggests that risk factors for accelerated impairment and dementia may diminish in importance as the neurodegenerative process advances.
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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 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.007 | 0.001 |
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".