Deformation‐based morphometry analysis shows early degeneration in Nucleus basalis of Meynert in Subjective Cognitive Decline
Bibliographic record
Abstract
Abstract Background People with subjective cognitive decline (SCD+) are thought to be at greater risk of Alzheimer’s disease (AD). The Nucleus basalis of Meynert (NbM) has been shown to change early in AD (Fernández‐Cabello et al., 2020), and it is the main source of cholinergic projection to entorhinal cortex (EC) (Mesulam et al., 2013). We thus investigated if there was evidence of degeneration in the NbM, or EC in SCD+ participants compared to those without (SCD‐), and if there was a relationship between changes in these regions and SCD status using deformation‐based morphometry (DBM). Method Data included baseline visit MRI scans of 232 cognitively healthy older adults (148 SCD‐; 84 SCD+) from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) dataset (using only ADNI2). SCD status was extracted based on the cognitive change index (CCI) of the subjects reported in ADNIMERGE data (CCI ≥16). MRI resolution was increased to 0.5 mm isotropic voxel‐size before non‐linear registration to an ADNI‐based unbiased symmetric template. The resulting deformation fields were used to compute the Jacobian determinant map for each subject as a proxy for local volume. NbM, and EC masks were mapped to our high‐resolution template and mean determinant values inside these masks were estimated, and sex‐ and age‐corrected z‐scores were calculated. Two‐sample t‐tests were then used to compare the SCD+:SCD‐ differences. Result Figure 1 shows the mean z‐score values for NbM and EC regions for both SCD+ and SCD‐ groups. Results for left NbM showed a significant difference between two groups (p = .007), but not for the right NbM (p = .12). However, z‐scored EC volumes did not show any statistically significant difference between groups for either left (p = .58) or right region (p = .41). Conclusion Our results suggest that in SCD+ subjects, while the EC is still intact, neurodegeneration in the NbM appears to have already begun. Quantifying degeneration in the NbM may allow for early diagnosis of AD. Further research is needed to evaluate if such differences can be computed on an individual subject basis for use as a biomarker.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".