Mapping brain morphological and functional conversion patterns in amnestic MCI: a voxel-based MRI and FDG-PET study

Area of Science:

• Neuroimaging
• Neurology
• Alzheimer's Disease Research

Background:

• Amnestic mild cognitive impairment (aMCI) is a prodromal stage for Alzheimer disease (AD).
• Understanding the transition from aMCI to AD requires identifying early neurobiological markers.

Purpose of the Study:

• To investigate the morphological and functional brain changes associated with memory impairment in aMCI.
• To identify substrates predicting conversion from aMCI to Alzheimer disease.

Main Methods:

• Utilized brain MRI and FDG-PET in 20 aMCI patients and 12 controls.
• Tracked conversion to AD over a 2-year follow-up period.
• Compared grey matter density and glucose metabolism between converters, non-converters, and controls using SPM2.

Main Results:

• Converters showed reduced grey matter in the parahippocampal gyrus and thalami compared to controls.
• Hypometabolism was observed in the precuneus and posterior cingulate gyrus in both converters and non-converters versus controls.
• Converters exhibited greater hypometabolism in the left temporal cortex compared to non-converters.

Conclusions:

• Discrepancies between atrophy and hypometabolism, characteristic of AD, are evident at the aMCI stage.
• Posterior cingulate-precuneus hypometabolism may indicate early memory deficits.
• Left temporal cortex hypometabolism appears to be a marker for progression to Alzheimer disease.