A SYSTEMATIC REVIEW OF CHANGE POINT STUDIES ON COGNITIVE AND NEUROLOGIC OUTCOMES PRECEDING DEMENTIA
Bibliographic record
Abstract
Older adults who ultimately develop dementia experience accelerated cognitive decline long before diagnosis. The current systematic review aimed to summarize the literature on preclinical change points (CPs) in relation to mild cognitive impairment (MCI) and dementia, identifying the order in which cognitive and neurological outcomes decline and factors that modify the onset of decline. Eligible studies included preclinical MCI/dementia CP models for cognitive/neurological outcomes from longitudinal cohorts free of early-onset dementia or concurrent neurological disorders associated with cognitive decline. The search protocol yielded 16 eligible studies describing 9 cohorts (1 pre-MCI, 8 pre-dementia). Only the MCI cohort involved neuroimaging and motor outcomes, identifying CPs for increased ventricular cerebrospinal fluid volume (CP=3.66 years before onset [95% CI: 0.75–5.58]) and white matter (WM) hyperintensities (10.58 years [5.15-Unknown]). Gait resulted in the earliest CP at 12.10 years (8.10-Unknown), while finger tapping declined after diagnosis. Across domains, cognitive abilities declined roughly 3–4 years prior to MCI. The earliest observed CP for dementia was perceptual speed (10.90 years [7.50–14.40]). Verbal memory was most commonly measured, with CPs ranging from 1.00–8.60 years pre-diagnosis. The latest cognitive ability to decline was reading ability (0.40 years [-0.10–0.11]). Greater education, female gender, and involvement in cognitively-stimulating activities significantly delayed CP onset. CPs preceding Alzheimer’s disease occurred earlier than CPs preceding vascular dementia. The findings from this systematic review suggest that neurological and cognitive changes occur long before MCI/dementia diagnoses. Lifestyle, dementia type, and gender influence the onset of decline, but few studies evaluated CP moderators.
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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 | 0.011 | 0.064 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.010 | 0.011 |
| Bibliometrics | 0.010 | 0.012 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 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".