[P2–230]: USING CSF MARKERS TO VALIDATE METABOLIC AND SYNAPTIC DYSFUNCTION HYPOTHESES OF ALZHEIMER's DISEASE (AD): META‐ANALYSIS
Bibliographic record
Abstract
Alzheimer's disease (AD) is currently incurable and a majority of investigational drugs have failed clinical trials. One explanation for this failure is the invalidity of some hypotheses explaining AD pathogenesis. Recently, hypotheses centered on synaptic and metabolic dysfunction are increasingly implicated in AD. Importantly, these hypotheses can readily be validated using neurotransmitter and metabolite biomarkers. Meta-analysis allows for statistical comparison of existing CSF biomarker data extracted from multiple publications, providing a unique opportunity to rapidly validate AD hypotheses in silico. Pubmed and Google Scholar were comprehensively searched for published English articles, without date restrictions, for the keywords “AD”, “CSF”, and “human” plus biomarkers selected for synaptic and metabolic pathways. Synaptic biomarkers were acetylcholine, GABA, glutamine, and glycine. Metabolic biomarkers were glutathione, glucose, lactate, pyruvate, and 8 other amino acids. Only studies that measured biomarkers in both AD and controls, provided means, standard errors/deviation, and subject numbers were included. Data were extracted by six authors and checked by two for accuracy. The data were transformed to log ratio of the means (AD/Control) and analyzed by the random effects model in the meta-analysis software (Cochrane Review Manager). Of 435 identified publications, after exclusion and removal of duplicates, 35 articles were included comprising a total of 605 AD patients and 585 controls. The following biomarkers for synaptic and metabolic pathways were significantly changed in AD/controls: acetylcholine (average ratio 0.36, 95% CI 0.24–0.53, p<0.00001), GABA (0.68, 0.54–0.85, p<0.0008), pyruvate (0.48, 0.24–0.94, p=0.03), glutathione (1.11, 1.01–1.21, p=0.03), alanine (1.10, 0.98–1.23, p=0.09), and lactate (1.17, 0.98–1.39, p=0.09). This study provides proof of concept for the use of meta-analysis validation of AD hypotheses, specifically via robust evidence for the cholinergic hypothesis of AD. Our data disagree with the other synaptic hypotheses of glutamate excitotoxicity (normal glutamate) and GABAergic resistance to neurodegeneration (decreased GABA levels). With regards to metabolic hypotheses, the data supported upregulation of anaerobic glycolysis, pentose phosphate pathway (glutathione), and TCA anaplerosis (several metabolites involved). Future applications of meta-analysis indicate the possibility of further in silico evaluation and generation of novel hypotheses in the AD field.
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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 | 0.018 | 0.058 |
| Meta-epidemiology (narrow) | 0.004 | 0.001 |
| Meta-epidemiology (broad) | 0.013 | 0.052 |
| Bibliometrics | 0.005 | 0.008 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.003 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.010 | 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".