Effect of healthy aging on cerebral blood flow, CO<sub>2</sub> reactivity, and neurovascular coupling during exercise
Bibliographic record
Abstract
We sought to make the first comparisons of duplex Doppler ultrasonography-derived measures of cerebral blood flow during exercise in young and older individuals and to assess whether healthy aging influences the effect of exercise on neurovascular coupling (NVC) and cerebral vascular reactivity to changes in carbon dioxide (CVRco 2 ). In 10 healthy young (23 ± 2 yr; mean ± SD) and 9 healthy older (66 ± 3 yr) individuals, internal carotid artery (ICA) and vertebral artery (VA) blood flows were concurrently measured, along with middle and posterior cerebral artery mean blood velocity (MCAv mean and PCAv mean ). Measures were made at rest and during leg cycling (75 W and 35% maximum aerobic workload). ICA and VA blood flow during dynamic exercise, undertaken at matched absolute (ICA: young 336 ± 95, older 352 ± 155; VA: young 95 ± 43, older 100 ± 30 ml/min) and relative (ICA: young 355 ± 125, older 323 ± 153; VA: young 115 ± 48, older 110 ± 32 ml/min) intensities, were not different between groups ( P > 0.670). The PCAv mean responses to visual stimulation (NVC) were blunted in older versus younger group at rest (16 ± 6% vs. 23 ± 7%, P < 0.026) and exercise; however, these responses were not changed from rest to exercise in either group. The ICA and VA CVRco 2 were comparable in both groups and unaltered during exercise. Collectively, our findings suggest that 1) ICA and VA blood flow responses to dynamic exercise are similar in healthy young and older individuals, 2) NVC is blunted in healthy older individuals at rest and exercise but is not different between rest to exercise in either group, and 3) CVRco 2 is similar during exercise in healthy young and older groups. NEW & NOTEWORTHY Internal carotid artery and vertebral artery blood flow responses to dynamic exercise are similar in healthy young and older individuals. Neurovascular coupling and cerebrovascular carbon dioxide reactivity, two key mechanisms mediating the cerebral blood flow responses to exercise, are generally unaffected by exercise in both healthy young and older 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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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".