Abstract P61: Pulsatility Index Outperforms Conventional Imaging Markers in the Association With Cognition in Community Subjects
Bibliographic record
Abstract
Increase in pulsatility index (PI), measured by the transcranial Doppler (TCD), correlates with cognitive impairment and is associated with progression of non-demented patients into Alzheimer’s disease (AD) with dementia, suggesting that increase in small vessel resistance is a critical marker of cognitive decline. No study compared PI and MRI markers for small vessel disease or AD that have been shown to be associated with worse cognitive functions. The objectives of this study include: (i) compare PI against conventional MRI markers in its association with cognition, and (ii) investigate the association of PI and cognition in the presence of vascular risk factors. We measured clinical data and PI in the middle cerebral artery in 331 stroke- and dementia-free community subjects. General cognition was assessed using Hong Kong-Montreal Cognitive Assessment. Conventional imaging markers (including lacunes, white matter hyperintensities (WMH), brain parenchymal fraction (BPF), cerebral microbleeds, Alzheimer’s Disease Resemblance Atrophy Index (ADRAI)) were assessed by MRI. Linear regression models were used to compare the sensitivity of PI against conventional MRI markers (including WMH, BPF, ADRAI, lacune and cerebral microbleeds count), with age and years of education entered as covariates. PI was negatively associated with cognition (standardised b=-0.122, p=0.01). PI outperformed (standardised b=-0.118, p=0.012) other imaging markers and contributes to 1.1% change in the variance. PI was associated with higher systolic blood pressure (standardised b=0.122, p=0.028), and level of triglyceride (standardised b = 0.126, p = 0.021). To conclude, PI is associated with cognition, higher levels of blood pressure and triglycerides, suggesting a vascular component in cognitive decline. PI outperforms conventional MRI markers in the association with cognition in community subjects without dementia. As TCD is non-invasive, portable with a lower cost than MRI, PI may serve as a simple marker in monitoring cerebral small vessel resistance and cognition in older people.
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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 | 0.002 | 0.007 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".