Association between <b><i>BDNF</i></b> Polymorphism and Hypothalamic-Pituitary-Adrenal Activity in Later Adulthood
Bibliographic record
Abstract
Stress exposure over the lifespan is robustly associated with accelerated cognitive decline in later life. Brain-derived neurotrophic factor (BDNF) is shown to regulate activity of the hypothalamic-pituitary-adrenal axis. The objective of this study was to evaluate the association betweenthe BDNF polymorphism and indices of stress among adults aged 50+. Community-dwelling middle-aged and older adults provided a blood sample for BDNF genotyping. Participants also sampled their saliva 5 times/day for 3 consecutive days for the measurement of diurnal cortisol and underwent the Trier Social Stress Test (TSST) for the measurement of stress reactivity. Among 121 adults aged 50-67 years (78% female; 89% Caucasian), 74 participants were Val/Val carriers and 47 carried 1 copy of the Met allele. Repeated-measures analyses did not reveal an association between BDNF genotype and diurnal salivary cortisol (p = 0.63); however, analyses revealed that Met+ carriers displayed lower levels of cortisol secretion in response to the TSST compared with Val/Val carriers; F(4.43, 496.238) = 2.57, p = 0.032. This is the first study to evaluate the role of the BDNF polymorphism in stress physiology among older adults. Future studies are needed to evaluate the lifespan interconnections between BDNF and stress physiology.
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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 | 0.000 |
| 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".