O2‐03‐01: AMYLOIDOSIS INDUCES EARLY METABOLIC REORGANIZATION
Bibliographic record
Abstract
Cerebral glucose hypometabolism – indexed by 18-fluorodeoxyglucose ([F]FDG) positron emission tomography (PET) imaging – is a metabolic signature of Alzheimer's disease (AD) patients. More than providing regional estimations of glucose metabolism, [F]FDG network analyses constitute a sophisticated approach for analyzing [F]FDG data at the group level. [F]FDG networks have the potential for unraveling disease-related cerebral metabolic architecture abnormalities. Here, we developed a novel and refined metabolic brain network method that has the potential to significantly detect subtle alterations in glucose metabolism and applied this method to cognitively unimpaired (CU) amyloid positive (Aβ+) and amyloid negative (Aβ-) individuals. We hypothesized similar glucose metabolism between groups but a more disorganized metabolic brain network in the Aβ+ group. We selected the 186 CU individuals from the ADNI1 and ADNI2 studies who had available data for [F]FDG-PET and CSF Aβ1-42 (Elecsys® immunoassay). Aβ positivity cutoff was defined as <1098 pg/mL. CU individuals were divided in Aβ- (n=108) and Aβ+ (n=78). Standardized uptake value ratio (SUVr) were calculated using the pons as reference region. Kruskal-Wallis between-groups corrected by false discovery rate (FDR) were used to compare regions classically hypometabolic in AD. Group-based metabolic brain networks were constructed using 96 volumes of interest (VOIs). We defined representative networks by computing the group-wise mean correlation matrix based on 10000 random sub-sampling. Networks were corrected for multiple comparisons using FDR. Graph theoretical measures such as density and global efficiency were calculated for each of the subsamples. Statistical significance was set as p<0.05. Aβ+ and Aβ- individuals presented similar median SUVR values in regions classically associated with AD (parieto-temporal areas, precuneus, cingulate region, hippocampal formation and frontal cortex, figure 1). By contrast, a widespread hyposynchronyc pattern was identified in the Aβ+ group (Figure 2A-B). Graph measures demonstrates a lower global efficiency (Figure 2C) and decreased density (Figure 2D).
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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 | 0.000 |
| 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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 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".