154Asymptomatic Orthostatic Cerebral Hypoperfusion Is Common In Older Adults
Bibliographic record
Abstract
Orthostatic cerebral hypoperfusion (OCH) syndrome is a recently defined clinical entity whereby cerebral hypoperfusion exists in the absence of orthostatic hypotension (OH). Here we sought to determine the prevalence of OCH and asymptomatic OCH in an older adult population. A self-selected sample of n=80 older adults (age 87(6.1) years; 73.5% female) were recruited from a retirement village population living in Ontario, Canada. The protocol was approved by the local ethics committee. All participants underwent a supine-stand transition (AS). Orthostatic symptoms were quantified using an 8-point orthostatic symptoms scale. Beat-to-beat blood pressure (mmHg) was recorded throughout using a calibrated volume clamp method and used to define OH, while near-infra red spectroscopy (NIRS) measured relative changes in regional cerebral tissue oxygen saturation (tSO2 - %). Orthostatic cerebral hypoperfusion (OCH) was defined as an absolute drop of >4% from baseline in tSO2 in the absence of OH. 60.3% had IOH, 24.4% had OH 40 seconds after standing, and 6.4% had sustained OH. 34.6% (n = 27) had cerebral hypoperfusion on standing (drops >4% in tSO2) with at least 11% (n = 9) of the total population with OCH (cerebral hypoperfusion without concurrent OH). Over half (55%) of those with OCH were asymptomatic. Orthostatic cerebral hypoperfusion is common (11%) in older adults aged over 80 with over half of these asymptomatic. Individuals without symptoms may be at an increased risk of syncope or falls since they are unable to take avoidance countermeasures in response to silent cerebral hypoperfusion. Direct measures of cerebral hypoperfusion may be useful in the future evaluation of syncope and falls in older adults to identify these individuals.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".