Dynamic cerebral autoregulation in cognitively intact controls and in people with mild cognitive impairment
Bibliographic record
Abstract
BACKGROUND: Reductions in cerebral blood flow are associated with Alzheimer's Disease pathological changes and represent a potential therapeutic target. Measuring changes in middle cerebral artery velocity (MCAv) using transcranial Doppler ultrasound measurement of acute changes in MCAv during dynamic maneuvers and uncover relationships with cerebral autoregulation. We tested the hypothesis that changes in cerebral autoregulation are associated with clinical change in patients with mild cognitive impairment. METHODS: ). K-means clustering was used to split MCI participants into higher-standing-velocity (n = 9) and lower-standing-velocity (n = 21) groups. A one-way analysis of variance was employed to determine group differences for MoCA scores and dCA. A two-way repeated measures ANOVA assessed group by position (supine, nadir, standing) effects for cardiorespiratory and cerebrovascular indices. Significance was set to p <0.05. RESULTS: MoCA scores were significantly higher in controls and the higher-standing-velocity groups compared to the lower-standing-velocity group (Figure 2). dCA was enhanced in the lower-standing-velocity group compared to the higher-standing-velocity group (Figure 2) with an inverse relationship between dCA and standing MCAv at diastole. Interactions were observed for the resistance index, cerebrovascular resistance index, and MCAv at diastole (p = 0.045, 0.008, and, 0.004 respectively). Effects of position were observed for all cardiopulmonary and cerebrovascular metrics other than MCAv at systole. CONCLUSIONS: This is the first study investigating a supine-to-standing induced dCA response within a cohort of people with MCI. Contrary to our hypothesis, an enhanced dCA was observed in the higher-standing-velocity group compared to the lower-standing-velocity group despite the higher-standing-velocity group having greater cognitive scores. Interestingly, the higher-standing-velocity group with MCI and controls had similar MoCA scores and dCA. An enhanced dCA may be a compensatory mechanism in the neurodegenerative disease processes. The unexpected results highlight the importance of uncovering hemodynamic pathways in clinical populations and identifying the adaptions made to preserve cognitive function in the face of dementia.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".