PIB-Positive PET in Individuals with Early- but Not Late-Onset Frontotemporal Dementia (P6.326)
Bibliographic record
Abstract
OBJECTIVE: To compare PIB retention in early- and late-onset temporal-variant frontotemporal dementia (tvFTD), Alzheimer's disease (AD), and controls. BACKGROUND: The amyloid tracer, Pittsburgh compound B (PIB), identifies amyloid-β (Aβ) deposition in patients with AD. Frontotemporal dementia (FTD) patients typically have early-onset dementia and show low Aβ deposition. We hypothesized that clinical late-onset but not early-onset temporal-variant FTD (tvFTD) would have an increased Aβ load related to aging or temporal lobe vulnerability to neuropathologic changes. Resolving this question could clarify the role of future anti-amyloid interventions for tvFTD. DESIGN/METHODS: Following injection with PIB, PET scans were obtained in 11 participants with tvFTD (6 with onset before age 65 and 5 with late onset), 9 with probable AD, and 10 healthy controls over age 60. We extracted time activity curves from regions of interest and calculated standardized uptake value ratios (SUVR) by using a cerebellar reference. Hierarchical cluster analysis established our PIB-positive (PIB+) cutoff. RESULTS: The temporal lobe SUVR was significantly lower in the tvFTD group than controls. Seven of 9 AD, 1 of 10 controls, and 2 of 11 tvFTD (both early-onset) were PIB+. The PIB+ tvFTD participants did not have significant memory or visuospatial deficits (that would suggest a diagnosis of AD). CONCLUSIONS: Although the early- and late-onset tvFTD did not differ significantly, lower temporal lobe PIB retention in tvFTD patients than controls has not been previously reported. This may relate to partial volume effects on the PIB signal, however our group has shown similar group comparisons irrespective of partial volume correction. Alternatively, the proteinopathy of tvFTD, whether tauopathy or TDP-43-opathy, may protect against Aβ deposition. Future larger studies may reveal whether a significant minority of early-onset FTD patients exhibit amyloid deposition. Study Supported by: NIA grant 1R03AG034413-01A2, CAMH Foundation, Internal support from CAMH, Women of Baycrest (TWC).
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".