To compare the patterns of grey matter loss in subjects with amnestic Mild Cognitive Impairment (aMCI) who progress to Alzheimer's disease within a fixed clinical follow-up time versus those who remain stable.
Twenty-one aMCI subjects were identified from the Mayo Clinic Alzheimer's research program that remained clinically stable for their entire observed clinical course (aMCI-S), where the minimum required follow-up time from MRI to last follow-up assessment was three years. These subjects were age and gender-matched to 42 aMCI subjects who progressed to AD within 18 months of the MRI (aMCI-P). Each subject was then age and gender-matched to a control subject. Voxel-based morphometry (VBM) was used to assess patterns of grey matter atrophy in the aMCI-P and aMCI-S groups compared to the control group, and compared to each other.
The aMCI-P group showed bilateral loss affecting the medial and inferior temporal lobe, temporoparietal association neocortex and frontal lobes, compared to controls. The aMCI-S group showed no regions of grey matter loss when compared to controls. When the aMCI-P and aMCI-S groups were compared directly, the aMCI-P group showed greater loss in the medial and inferior temporal lobes, the temporoparietal neocortex, posterior cingulate, precuneus, anterior cingulate, and frontal lobes than the aMCI-S group.
The regions of loss observed in aMCI-P are typical of subjects with AD. The lack of grey matter loss in the aMCI-S subjects is consistent with the notion that patterns of atrophy on MRI at baseline map well onto the subsequent clinical course.