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Curr Alzheimer Res. 2009 Aug;6(4):347-61.

Baseline MRI predictors of conversion from MCI to probable AD in the ADNI cohort.

Author information

  • 1IU Center for Neuroimaging, Division of Imaging Sciences, Department of Radiology, Indiana University School of Medicine, 950 W Walnut St, R2 E124, Indianapolis, IN 46202, USA.

Abstract

The Alzheimer's Disease Neuroimaging Initiative (ADNI) is a multi-center study assessing neuroimaging in diagnosis and longitudinal monitoring. Amnestic Mild Cognitive Impairment (MCI) often represents a prodromal form of dementia, conferring a 10-15% annual risk of converting to probable AD. We analyzed baseline 1.5T MRI scans in 693 participants from the ADNI cohort divided into four groups by baseline diagnosis and one year MCI to probable AD conversion status to identify neuroimaging phenotypes associated with MCI and AD and potential predictive markers of imminent conversion. MP-RAGE scans were analyzed using publicly available voxel-based morphometry (VBM) and automated parcellation methods. Measures included global and hippocampal grey matter (GM) density, hippocampal and amygdalar volumes, and cortical thickness values from entorhinal cortex and other temporal and parietal lobe regions. The overall pattern of structural MRI changes in MCI (n=339) and AD (n=148) compared to healthy controls (HC, n=206) was similar to prior findings in smaller samples. MCI-Converters (n=62) demonstrated a very similar pattern of atrophic changes to the AD group up to a year before meeting clinical criteria for AD. Finally, a comparison of effect sizes for contrasts between the MCI-Converters and MCI-Stable (n=277) groups on MRI metrics indicated that degree of neurodegeneration of medial temporal structures was the best antecedent MRI marker of imminent conversion, with decreased hippocampal volume (left > right) being the most robust. Validation of imaging biomarkers is important as they can help enrich clinical trials of disease modifying agents by identifying individuals at highest risk for progression to AD.

PMID:
19689234
[PubMed - indexed for MEDLINE]
PMCID:
PMC2764863
Free PMC Article

Images from this publication.See all images (7)Free text

Fig. (1)
Fig. (2). Group comparisons of healthy control participants and patient groups using a one-way ANOVA of GM density maps.
Fig. (3). Group comparisons of patient groups based on baseline diagnosis and one year conversion status using a one-way ANOVA of GM density maps.
Fig. (4). Extracted GM density, volume, and cortical thickness values from medial temporal lobe structures.
Fig. (5). Cortical thickness values from the temporal lobe extracted using automated parcellation.
Fig. (6). Parietal cortical thickness values extracted using automated parcellation.
Fig. (7). Effect sizes of the comparison between MCI-Stable and MCI-Converter groups evaluated for selected imaging biomarkers.
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