P2‐253: Increased creatine in the posterior cingulate cortex in early Alzheimer's disease: A high‐field magnetic resonance spectroscopy study
Bibliographic record
Abstract
Alzheimer's disease (AD) is associated with abnormalities in the levels of several important brain metabolites. In most previous magnetic resonance spectroscopy (MRS) studies, total creatine (Cr) concentration (creatine plus phosphocreatine) has been used as an internal reference to obtain a relative ratio of other metabolites (e.g., N-acetyl aspartate (NAA)/Cr). This is done even though the level of Cr itself may also vary in AD, a finding that remains to be validated. In this study, we examined AD-associated changes in metabolite levels using high-field MRS, with a focus on possible changes in Cr concentration in early AD. Sixteen patients with early AD (76.7 ± 7.9 years old, 9 women) and 20 cognitively normal older adults (CN; 73.5 ± 6.3 years old, 12 women) were scanned at baseline and at 6 months. Single Voxel proton (SV 1H) MRS data were acquired using a 4 Tesla MRI (Oxford-Varian human imaging system) and the LASER pulse sequence (Localization by Adiabatic Selective Refocusing; TE = 46ms, NEX = 128). Two voxels (6.4 cm3 each) were located in the posterior cingulate gyri (PCG) and the left dorsal lateral prefrontal cortex (DLPFC). The MRS spectra were fitted using fitMAN, incorporating tissue type and partial volume adjustment from T1-weighted high-resolution anatomical imaging. A higher level of Cr concentration was observed in the PCG voxel in AD (10.73 ± 0.28) compared to CN (9.91 ± 0.23; p<0.05). In contrast, no group difference in Cr was found in the DLPFC voxel (ps>0.05), while a significantly lower Glu/Cr ratio was observed in AD (0.49 ± 0.04) compared to CN (0.59 ± 0.03, p<0.05). Meanwhile, the NAA/Cr ratio was significantly lower (ps<0.001) in AD than in CN in both the PCG (Δ = 0.12 ± 0.02) and the DLPFC (Δ = 0.18 ± 0.03). Using solely the absolute metabolite levels of Cr, NAA, and Glu in the DLPFC, the accuracy for the identification of individuals with early AD (vs. CN) reached 0.84 (95% CI = 0.74–0.93). An increased Cr concentration in PCG may be associated with the development of AD, reflecting the underlying neurodegenerative pathology and the disturbed balance of energy supply and energy demand. The study also suggests that combining information on changes of Cr levels and those of other major metabolites can help improve AD identification.
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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) | 0.001 | 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 | 0.001 | 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".