P1‐177: Extensive white matter burden represents a new radiological phenotype in a distinct population of ad patients
Bibliographic record
Abstract
Previous neuropathological observations and neuroimaging studies in pathologically-proven non-AD dementias showed that tauopathies have characteristic tau inclusions throughout white matter (WM) brain regions, with relative sparing of grey matter (GM). However, the association between surrogate CSF markers of tau-induced neurodegeneration and WM structural changes in patients with Alzheimer's disease (AD) remains overlooked. In this study, we compared clinically-defined AD patients with and without CSF evidence of tau neurodegeneration, in order to radiologically characterize tau-dependent neurodegenerative processes in AD. Data were obtained from the ADNI (Alzheimer's Disease Neuroimaging Initiative) database (adni.loni.usc.edu) on all individuals with a baseline diagnosis of AD or normal control (CN), baseline T1-weighted brain MRI and CSF biomarkers. For the AD group, only patients with CSF amyloid-β1-42levels below the 192 pg/mL threshold (suggestive of significant cerebral amyloidopathy) were retained for further analyses. Selected AD patients were dichotomized using previously published CSF total tau (T-Tau) cutoff values: T-Tau positive (n=145, males=72) and T-Tau negative (n=63, males=48) patients, characterized by CSF T-Tau values above or below the 93 pg/mL threshold, respectively. Voxel-based morphometry (VBM) was applied to compare whole-brain patterns of GM and WM volume in T-Tau positive and negative patients. Statistical analyses were performed by using SPM12 software. Age, gender, education, MMSE score, MRI field strength and intracranial volume were included as nuisance variables in the analysis. T-Tau positive and negative patients were comparable in terms of age, dementia clinical severity, ApoE4 phenotype, and neuropsychological impairment. Only T-tau positive AD exhibited significant (FWE corrected) and extensive WM volume loss in bilateral medial temporal regions compared to CN, in particular in the parahyppocampal WM. When compared to T-tau negative AD, T-tau positive patients showed no GM volume reduction. Instead, they presented extensive WM atrophy in bilateral fornix, corona radiata and centrum semiovale (p<0.001 uncorrected).
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".