Related Experiment Videos
Regional metabolic patterns in mild cognitive impairment and Alzheimer's disease: A 1H MRS study
1Departments of Diagnostic Radiology, Mayo Clinic, Rochester, MN, USA.
Background:
Mild cognitive impairment (MCI) is a recently described transitional clinical state between normal aging and AD. Assuming that amnestic MCI patients had pathologic changes corresponding to an early phase and probable AD patients to a later phase of the disease progression, the authors could approximate the temporal course of proton MR spectroscopic (1H MRS) alterations in AD with a cross-sectional sampling scheme.
Methods:
The authors compared 1H MRS findings in the superior temporal lobe, posterior cingulate gyri, and medial occipital lobe in 21 patients with MCI, 21 patients with probable AD, and 63 elderly controls. These areas are known to be involved at different neurofibrillary pathologic stages of AD.
Results:
The N-acetylaspartate (NAA)/creatine (Cr) ratios were significantly lower in AD patients compared to both MCI and normal control subjects in the left superior temporal and the posterior cingulate volumes of interest (VOI) and there were no between-group differences in the medial occipital VOI. Myoinositol (MI)/Cr ratios measured from the posterior cingulate VOI were significantly higher in both MCI and AD patients than controls. The choline (Cho)/Cr ratios measured from the posterior cingulate VOI were higher in AD patients compared to both MCI and control subjects.
Conclusion:
These findings suggest that the initial 1H MRS change in the pathologic progression of AD is an increase in MI/Cr. A decrease in NAA/Cr and an increase in Cho/Cr develop later in the disease course.
Insights
Proton MR spectroscopic (1H MRS) analysis reveals that elevated myoinositol/creatine (MI/Cr) ratios mark the initial stage of Alzheimer's disease (AD) progression, preceding decreases in N-acetylaspartate/creatine (NAA/Cr) and increases in choline/creatine (Cho/Cr).
Area of Science:
- Neuroimaging
- Biomarkers
- Alzheimer's Disease Research
Background:
- Mild cognitive impairment (MCI) represents a transitional stage between normal aging and Alzheimer's Disease (AD).
- Proton magnetic resonance spectroscopic (1H MRS) imaging offers a method to study biochemical changes in vivo.
- This study investigates 1H MRS alterations in relation to AD pathology progression.
Purpose of the Study:
- To characterize the temporal sequence of 1H MRS changes in the brains of patients with MCI and AD.
- To correlate 1H MRS findings with known neurofibrillary pathology stages in AD.
- To differentiate early AD-related biochemical alterations from those in later stages.
Main Methods:
- Comparison of 1H MRS findings in the superior temporal lobe, posterior cingulate, and medial occipital lobes.
- Inclusion of 21 MCI patients, 21 probable AD patients, and 63 elderly controls.
- Analysis of metabolite ratios including N-acetylaspartate/creatine (NAA/Cr), myoinositol/creatine (MI/Cr), and choline/creatine (Cho/Cr).
Main Results:
- Significantly lower NAA/Cr ratios were observed in AD patients compared to MCI and controls in specific brain regions.
- Myoinositol/creatine (MI/Cr) ratios were elevated in both MCI and AD patients compared to controls in the posterior cingulate.
- Choline/creatine (Cho/Cr) ratios were higher in AD patients than in MCI and control subjects in the posterior cingulate.
Conclusions:
- The initial 1H MRS alteration in AD progression is an increase in MI/Cr.
- Decreased NAA/Cr and increased Cho/Cr are indicative of later stages in the AD disease course.
- 1H MRS can provide insights into the biochemical trajectory of AD.