Synaptic Biomarkers in Alzheimer's Dementia: A Meta‐Analysis
Bibliographic record
Abstract
Abstract Background Alzheimer's dementia (AD) is a neurodegenerative condition characterized by progressive cognitive decline. Synaptopathy—defined as loss and dysfunction of existing synapses—is a hallmark pathological feature of AD and can directly contribute to underlying cognitive deficits. In this study, we meta‐analyzed several cerebrospinal fluid (CSF) and blood exosomal biomarkers associated with synaptopathy in AD and healthy controls (HCs). Method Original peer‐reviewed articles that reported synaptic biomarker concentrations in CSF or blood exosomes were reviewed. Specifically, synaptosome associated protein‐25 (SNAP‐25), growth associated protein‐43 (GAP‐43), neuronal pentraxin receptor (NPTXR), neuronal pentraxin‐1 (NPTX‐1), neuronal pentraxin‐2 (NPTX‐2), complexin‐2, syntaxin‐1B, syntaxin‐7, and vesicle‐associated membrane protein‐2 (VAMP‐2) in AD and HCs were included for meta‐analysis. A random‐effects model was used to determine standardized mean differences (SMDs) and 95% confidence intervals (CIs). Heterogeneity was quantified using I 2 . Result The meta‐analysis included 43 study cohorts. In CSF, concentrations of SNAP‐25 (N AD /N HC = 394/539, SMD [95% CI] = 1.08 [0.73, 1.42], p < 0.001; I 2 = 81.43%), GAP‐43 (N AD /N HC = 851/557, SMD [95% C] = 1.02 [0.69, 1.34], p < 0.001; I 2 = 83.97%), and VAMP‐2 (N AD /N HC = 398/490, SMD [95% CI] = 0.32 [0.05, 0.60], p = 0.02; I 2 = 64.91%) were elevated, and NPTXR (N AD /N HC = 575/470, SMD [95% CI] = ‐0.68 [‐0.96, ‐0.40], p < 0.001; I 2 = 75.59%), NPTX‐1 (N AD /N HC = 344/333, SMD [95% CI] = ‐0.48 [‐0.64, ‐0.31], p < 0.001; I 2 = 9.05%), and NPTX‐2 (N AD /N HC = 462/496, SMD [95% CI] = ‐0.78 [‐1.02, ‐0.54], p < 0.001; I 2 = 66.43%) were decreased in AD compared to HCs. In blood exosomes, SNAP‐25 (N AD /N HC = 161/159, SMD [95% CI] = ‐1.05 [‐1.28, ‐0.82], p < 0.001; I 2 = 0%) and GAP‐43 (N AD /N HC = 110/110, SMD [95% CI] = ‐1.66 [‐2.43, ‐0.88], p < 0.001; I 2 = 77%) concentrations were decreased in AD. Conclusion This study found that several synaptic biomarkers were significantly altered in AD in CSF and blood exosomes. There was significant heterogeneity for most comparisons (with the exception of CSF NPTX‐1 and blood exosome SNAP‐25) that remains to be explored. Nonetheless, further review of the identified biomarkers may provide fundamental insight into AD pathophysiology and disease trajectory.
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How this classification was reachedexpand
Direct model labels (unvalidated)
Per-model category and study-design labels from the labeling rounds. They are machine output, unvalidated, and the disagreement between models ships as data. No study design here is MEDLINE-validated yet.
| Model arm | Categories | Study design | Confidence |
|---|---|---|---|
| gemma | no category Domain: not available · Genre: Empirical About the Canadian research system: no · About a Canadian topic: no | Meta-analysis | low |
| gpt | no category Domain: not available · Genre: Review About the Canadian research system: no · About a Canadian topic: no | Meta-analysis | medium |
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 | 0.015 | 0.024 |
| Meta-epidemiology (narrow) | 0.004 | 0.002 |
| Meta-epidemiology (broad) | 0.014 | 0.056 |
| Bibliometrics | 0.004 | 0.005 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.001 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.004 | 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, unvalidatedLabeled directly by 2 models reading the full record.
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".