Cerebrovascular pulsatility following long duration spaceflight is associated with changes in pulse pressure and carotid artery stiffness
Bibliographic record
Abstract
Abstract Central artery stiffening increases the haemodynamic pulsations transmitted downstream towards target organs, including the brain. While recent evidence suggests that long duration spaceflight is associated with reduced common carotid artery (CCA) distensibility, cerebrovascular pulsatility has not been extensively characterized in astronauts. This study investigated changes in pulsatility from pre‐flight to after 6 months in space, using a secondary analysis of data from four separate experiments. Middle cerebral artery blood velocity (MCAv) was measured during supine rest in 27 astronauts (20 men, 7 women). In subsets of this cohort, we measured CCA distensibility and β stiffness ( n = 20), and CCA wave intensity ( n = 12). The overall increase in MCAv pulsatility index (PI mca ) from pre‐flight to post‐flight was not significant (0.73 ± 0.12 vs. 0.77 ± 0.11, P = 0.060, partial η 2 = 0.13). However, individual changes in PI mca were directly associated with changes in estimated aortic pulse pressure ( r = 0.51, P = 0.007) and β stiffness ( r = 0.54, P = 0.015), and inversely associated with changes in distensibility ( r = −0.62, P = 0.003), in separate bivariate analyses. Wave intensity analysis suggested a reduction in normalized wave reflection ( P = 0.07), and that forward compression wave amplitude was directly related to PI mca ( r = 0.64, P = 0.025). These findings suggest that PI mca in the days immediately following spaceflight is a function of lower carotid distensibility, highlighting the interplay between arterial stiffness and cerebrovascular pulsatility.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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) | 0.001 | 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".