P2‐408: DEFICIT ACCUMULATION IN THE BRAIN MEDIATES THE EFFECT OF AGE ON COGNITION: AN APPLICATION OF THE BRAIN ATROPHY AND LESION INDEX USING CLINICAL ROUTINE MRI
Bibliographic record
Abstract
Brain aging is associated with cognitive decline and the accumulation of multiple MRI-revealed changes. How deficits in the brain combine to affect cognition is not well understood. In this study, we summarize common changes in the whole brain on MRI using the Brain Atrophy and Lesion Index (BALI), applying clinical routine sequences. Our objective is to understand to what extent the accumulation of deficits in the brain mediates the effect of age on cognition. Data were collected from 170 adults aged 45–82 years (women =60.0%; age =62.9±9.3 years) who were with normal cognition (n=120), mild cognitive impairment (n=30), or Alzheimer's disease (n=20). BALI scores were generated for each subject by evaluating 3.0T MRI routinely acquired in clinical settings (i.e., T1-weighted, T2-weighted, T2-weighted fluid-attenuated inversion recovery, and T2*-weighted gradient-recalled echo images). Global cognition was assessed using the Mini Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), and the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog). Associations between age, BALI, and cognition were tested using correlation and regression analyses. Mean differences in the measures among diagnostic groups were examined using Chi2 and non-parametric Kruskal-Wallis tests. The mediation effect of BALI relating age and cognition was analyzed using the PROCESS macro implemented in the SPSS software. The BALI and cognition scores were correlated (r2≥0.22, p<0.001, Figure 1); each changed with age (r2=0.27, p<0.001 for BALI vs. age, Figure 2; r2≥0.08, p<0.001 for cognition vs. age, Figure 3) and differed significantly by diagnosis (K–W/χ2=39.95, p<0.001). The BALI showed a strong mediation effect between age and cognition (−0.29; confidence interval CI: −0.42, −0.19 for MMSE; −0.26, 95% CI: −0.39, −0.16 for MoCA; 0.34, CI: 0.22, 0.45 for ADAS-cog). The mediation effect of BALI accounted for 78% to 86% (depending on cognitive scores) of the age effect on cognition, adjusting for sex and education (Table 1).
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".