Apolipoprotein E genotype and MRI-detected brain alterations pertaining to neurodegeneration: A systematic review
Bibliographic record
Abstract
Abstract Introduction The effect of apolipoprotein E (APOE) genotype, particularly APOE ε4, the main genetic risk factor for late-onset Alzheimer’s disease (LOAD), has been widely explored in neuroimaging studies pertaining to older adults. The goal of this systematic review was to review the literature on the relationship between carriage of the APOE ε4 allele and grey matter (GM) changes across various age groups and its influence on neurodegeneration as evidenced by structural magnetic resonance imaging (MRI). Methods A search of the electronic databases Pubmed, Scopus, Ovid and Cochrane was carried out till March 2020. Only studies published in English were included. Risk of bias of each study was assessed using the modified Newcastle-Ottawa Scale. Results A total of 115 articles met the inclusion criteria. Methodological quality varied from poor to good. There is moderate evidence of reduced GM volume in the middle frontal gyrus, precuneus, hippocampus, hippocampal subfields, amygdala, parahippocampal gyrus, middle temporal lobe, whole temporal lobe, temporal pole, and posterior cingulate cortex in APOE ε4 carriers. Conclusion The present data supports the utility of the hippocampal GM volume to evaluate early structural neurodegenerative changes that occurs in APOE ε4 positive elderly individuals who are at increased risk of developing LOAD. Furthermore, the evidence supports serial measurements and comparison of hippocampal volume based on age group, to track the progression of neurodegeneration in APOE ε4 carriers. Additional longitudinal studies are necessary to confirm whether the combination of MRI-detected hippocampal atrophy with APOE ε4 carrier status, can better predict the development of LOAD in cognitively normal individuals.
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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 | 0.007 | 0.031 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.009 | 0.007 |
| Bibliometrics | 0.010 | 0.010 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".