Association of CSF Aβ, amyloid PET, and cognition in cognitively unimpaired elderly adults
Bibliographic record
Abstract
<h3>Objective</h3> To compare CSF β-amyloid (Aβ) and florbetapir PET measurements in cognitively unimpaired (CU) elderly adults in order to detect the earliest abnormalities and compare their predictive effect for cognitive decline. <h3>Methods</h3> A total of 259 CU individuals were categorized as abnormal (+) or normal (−) on CSF Aβ<sub>1-42</sub>/Aβ<sub>1-40</sub> analyzed with mass spectrometry and Aβ PET measured with <sup>18</sup>F-florbetapir. Simultaneous longitudinal measurements of CSF and PET were compared for 39 individuals who were unambiguously Aβ-negative at baseline (CSF−/PET−). We also examined the relationship between baseline CSF/PET group membership and longitudinal changes in CSF Aβ, Aβ PET, and cognition. <h3>Results</h3> The proportions of individuals in each discordant group were similar (8.1% CSF+/PET− and 7.7% CSF−/PET+). Among baseline Aβ-negative (CSF−/PET−) individuals with longitudinal CSF and PET measurements, a larger proportion subsequently worsened on CSF Aβ (odds ratio 4 [95% confidence interval (CI) 1.1, 22.1], <i>p</i> = 0.035) than Aβ PET over 3.5 ± 1.0 years. Compared to CSF−/PET− individuals, CSF+/PET− individuals had faster (estimate 0.009 [95% CI 0.005, 0.013], <i>p</i> < 0.001) rates of Aβ PET accumulation over 4.4 ± 1.7 years, while CSF−/PET+ individuals had faster (estimate −0.492 [95% CI −0.861, −0.123], <i>p</i> = 0.01) rates of cognitive decline over 4.5 ± 1.9 years. <h3>Conclusions</h3> The proportions of discordant PET and CSF Aβ-positive individuals were similar cross-sectionally. However, unambiguously Aβ-negative (CSF−/PET−) individuals are more likely to show subsequent worsening on CSF than PET, supporting the idea that CSF detects the earliest Aβ changes. In discordant cases, only PET abnormality predicted cognitive decline, suggesting that abnormal Aβ PET changes are a later phenomenon in cognitively normal individuals.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".