Blood pressure levels and brain volume reduction
Bibliographic record
Abstract
OBJECTIVE: High blood pressure (BP) levels may be associated with brain volume reduction and may contribute to brain atrophy in key brain regions involved in cognition and susceptible to neurodegeneration in Alzheimer's disease. The purpose of this work was to systematically review and quantitatively synthesize the association of BP levels with brain volume reduction in humans. METHODS: An English Medline, Cochrane Library and PsycINFO search was conducted in June 2012 using the Medical Subject Heading terms 'Blood pressure', 'Hypertension', 'Brain mapping' and 'Brain atrophy'. RESULTS: Of the 609 screened abstracts, 28 studies (4.6%) were included in the qualitative analysis. Twenty-six studies (92.9%) showed a significant association of higher BP levels and/or hypertension with total and/or regional brain volume reduction, the frontal and temporal lobes being particularly affected. In addition, four other studies reported an association between lower BP levels and brain volume reduction. Due to the heterogeneity of methodology and outcomes, random-effects meta-analyses of the mean difference of brain volume could be performed on only seven studies, with a total of 709 cases with hypertension and 1001 controls without hypertension. The findings showed no between-group difference regarding the whole-gray matter volume (summary mean difference = 2.42 cm [95% confidence interval (CI): -2.13 to 6.96]). Conversely, cases with hypertension exhibited lower hippocampus volume compared with controls [summary mean difference = -0.10 cm (95% CI: -0.17 to -0.02)]. CONCLUSION: These findings provide evidence that high BP levels lead to brain volume reduction, specifically in hippocampus, and may be an important factor that contributes to neurodegeneration in Alzheimer's disease.
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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 | 0.012 | 0.053 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.006 | 0.008 |
| Bibliometrics | 0.011 | 0.009 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".