APOE4 status is related to differences in memory-related brain function in asymptomatic older adults: Baseline analysis of the PREVENT-AD task fMRI dataset
Bibliographic record
Abstract
Abstract Episodic memory decline is one of the earliest symptoms of late-onset Alzheimer’s Disease (AD) and older adults with the apolipoprotein E e4 (+APOE4) genetic risk factor for AD may exhibit altered patterns of memory-related brain activity years prior to initial symptom onset. In the current study we report the baseline episodic memory task fMRI results from the PRe-symptomatic EValuation of Experimental or Novel Treatments for Alzheimer’s Disease (PREVENT-AD) study in Montreal, Canada, in which 327 healthy older adults, within 15 years of the parent’s conversion to AD, were scanned. During the task fMRI protocol volunteers were scanned as they encoded and retrieved object-location spatial source associations. The task was designed to discriminate between brain activity related to successful spatial source recollection and failures in spatial source recollection, with memory for only item (object) memory. Multivariate task-related partial least squares (task PLS) was used to test the hypothesis that +APOE4 adults with a family history of AD would exhibit altered patterns of brain activity in the recollection-related memory network, comprised of medial frontal, parietal and medial temporal cortices, compared to APOE4 non-carriers (-APOE4). We also tested for group differences in the correlation between event-related brain activity and memory performance in +APOE4 compared to -APOE4 adults using behavioral-PLS (B-PLS). We found group similarities in memory performance and in task-related brain activity in the recollection network. However, the B-PLS results indicated there were group differences in brain activity-behavior correlations in ventral occipito-temporal, medial temporal, and medial prefrontal cortices during episodic encoding. These findings are consistent with previous literature on the influence of APOE4 on brain activity and provide new perspective on potential gene-based differences in brain-behavior relationships in people with parental history of AD. Future research should further investigate the potential to distinguish risk of AD development based on memory performance and associated patterns of brain activity.
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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 | 0.000 | 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) | 0.001 | 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".