The role of hippocampal subfield and medial temporal lobe volumes in subjective cognitive decline
Bibliographic record
Abstract
BACKGROUND: Subjective cognitive decline (SCD), defined as self-perceived memory decline with normal test performance, may indicate preclinical Alzheimer's disease (AD). While medial temporal lobe (MTL) atrophy is a key neuroimaging biomarker for AD, specific atrophy patterns in SCD remain unclear. Neuroimaging studies also indicate that hippocampal subfields, particularly the CA1 and subiculum, are among the earliest affected in AD. However, the literature on volumetric alterations in the hippocampal subfields and other MTL subregions in SCD is inconsistent. One potential reason is failure to account for previous diagnosis of depression, which itself is associated with hippocampal atrophy, in SCD samples. This study compared MTL and hippocampal subfield volumes in older adults with SCD and cognitively unimpaired (CU) adults without prior or current depression and examined their associations with quantitative measures of subjective memory. METHOD: Fifty-one participants (26 SCD (13M, age 70.6 ± 5.1) and 25 CU (10M, age 71.4 ± 7.4) without psychiatric history completed the Memory Functioning Questionnaire (MFQ) and high-resolution magnetic resonance imaging (MRI) of the MTL at 3Tesla. The Automatic Segmentation of Hippocampal Subfields (ASHS) pipeline and manual segmentation were used to extract regions-of-interest (ROIs). ANCOVA was used to compare group differences in ROIs. Regression analyses were conducted to examine associations between MFQ scores and ROIs. RESULT: Relative to CU, parahippocampal volume was smaller bilaterally in SCD [left: F(1, 48 =5.87, p =0.019; right: F (1, 48)=5.35, p =0.026], after controlling for age, sex, and total intracranial volume. A trend towards smaller left subicular volume was observed in SCD [F(1,48)=3.86, p =0.055]. Multivariable regression analyses controlling for age, sex, and intracranial volume showed positive associations between left subiculum volumes and MFQ-Seriousness of Forgetting subscale scores, and between left CA1 volumes and MFQ-Frequency of Forgetting subscale scores. CONCLUSION: These preliminary findings implicate the subiculum and parahippocampal gyrus in the neurobiology of SCD and suggest a predominant effect of the left hemisphere. Further, these data are not confounded by the presence of past or current depression in our sample. These findings require replication using larger samples of SCD with biomarker evidence of AD neuropathology.
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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) | 0.000 | 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".