Brain fuel uptake during aging and in Alzheimer's disease: A positron emission tomography and MRI study comparing glucose and a new ketone tracer – <sup>11</sup>C-acetoacetate
Bibliographic record
Abstract
Lower regional cerebral metabolic rate of glucose (CMR g ) is present during normal aging and may contribute to the development or progression of Alzheimer's disease (AD) (1) . However, with only [ 18 F]-fluorodeoxyglucose ( 18 F-FDG) available to measure brain energy metabolism by positron emission tomography (PET), it remains unclear whether lower CMR g in AD represents a global problem of brain energy substrate metabolism or is specific to glucose. The ketones, acetoacetate (AcAc) and beta-hydroxybutyrate, are the brain's main alternative energy substrates to glucose during prolonged fasting or in other forms of glucose deficit, so we compared brain glucose and AcAc metabolism in three groups: young healthy adults, healthy elderly and mild AD. Our objectives were to: (i) quantify CMR g and brain [ 11 C]-AcAc uptake (CMR a ) by PET, and (ii) compare regional brain volumes, CMR g and CMR a between healthy young and elderly persons, and between the healthy elderly and mild AD.
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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 | 0.001 | 0.000 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".