Vitamin <scp>B12</scp> Levels Association with Functional and Structural Biomarkers of Central Nervous System Injury in Older Adults
Bibliographic record
Abstract
OBJECTIVE: Vitamin B12 (B12) plays a critical role in fatty- and amino-acid metabolism and nucleotide synthesis. While the association between B12 deficiency and neurological dysfunction is well-known, the exact threshold for adequacy remains undefined in terms of functional impairment and evidence of injury. The objective was to assess whether B12 levels within the current normal range in a cohort of healthy older adults may be associated with measurable evidence of neurological injury or dysfunction. METHODS: We enrolled 231 healthy elderly volunteers (median age 71.2 years old) with a median B12 blood concentration of 414.8 pmol/L (as measured by automated chemiluminescence assay). We performed multifocal visual evoked potential testing, processing speed testing, and magnetic resonance imaging to assess neurological status. Moreover, we measured serum biomarkers of neuroaxonal injury, astrocyte involvement, and amyloid pathology. RESULTS: Low (log-transformed) B12, especially decreased holo-transcobalamin, was associated with visual evoked potential latency delay (estimate = -0.04; p = 0.023), processing speed impairment (in an age-dependent manner; standardized β = -2.39; p = 0.006), and larger volumes of white matter hyperintensities on MRI (β = -0.21; p = 0.039). Remarkably, high levels of holo-haptocorrin (biologically inactive fraction of B12) correlated with serum levels of Tau, a biomarker of neurodegeneration (β = 0.22, p = 0.015). INTERPRETATION: Healthy older subjects exhibit neurological changes at both ends of the measurable "normal" B12 spectrum. These findings challenge our current understanding of optimal serum B12 levels and suggest revisiting how we establish appropriate nutritional recommendations. ANN NEUROL 2025;97:1190-1204.
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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 | 0.001 | 0.001 |
| 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".