Differential cortical atrophy in subgroups of mild cognitive impairment.
OBJECTIVE
To compare gray matter brain volumes in patients diagnosed with subtypes of mild cognitive impairment (MCI) (those with a focal amnestic disorder and those with more diffuse cognitive dysfunction) with those of elderly controls.


METHODS
Magnetic resonance imaging volumetric study of MCI subgroups (MCI-amnestic [MCI-A], and MCI-multiple cognitive domain [MCI-MCD]) using a whole brain voxel-based analysis.


METHODS
Referral dementia clinic. Patients Thirty-seven patients with MCI (age range, 49-85 years; MCI-A, n = 9; MCI-MCD, n = 28) and 47 control subjects (age range, 55-81 years).


METHODS
Volumetric anatomical magnetic resonance imaging differences between MCI subgroups and normal controls, and between patients with MCI who progressed to dementia. Magnetic resonance imaging scans were analyzed using statistical software SPM99.


RESULTS
Overall, the patients with MCI had significantly decreased volume in the hippocampus and middle temporal gyrus, bilaterally, compared with control subjects. Compared with patients with MCI-MCD, patients with MCI-A had significant volume loss of the left entorhinal cortex and inferior parietal lobe. Compared with patients with MCI-A, patients with MCI-MCD had significantly reduced volume of the right inferior frontal gyrus, right middle temporal gyrus, and bilateral superior temporal gyrus. Patients with MCI who progressed to Alzheimer disease during follow-up (mean interval 2 years, maximum 4.5 years), showed greater atrophy in the left entorhinal cortex, bilateral superior temporal gyri, and right inferior frontal gyrus compared with those who did not progress.


CONCLUSIONS
These data provide evidence of distinct brain structural abnormalities in 2 groups of patients with MCI. While both have mesial temporal and cortical volume loss, those with a focal memory deficit have more involvement of the mesial temporal structures and less involvement of the neocortical heteromodal association areas than those patients with MCI with diffuse cognitive dysfunction. Thus, MCI may represent a more heterogeneous group than currently conceived, possibly reflecting 2 different etiological processes to dementia. These data also suggest that these structural abnormalities precede the development of Alzheimer disease.
Bell-McGinty
Sandra
S
Department of Psychiatry, University of Pittsburgh Medical Center, PA, USA.
Lopez
Oscar L
OL
Meltzer
Carolyn Cidis
CC
Scanlon
Joelle M
JM
Whyte
Ellen M
EM
Dekosky
Steven T
ST
Becker
James T
JT
D000368:Aged; D000369:Aged, 80 and over; D001284:Atrophy / Q000473:pathology; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000473:pathology*; D003072:Cognition Disorders / Q000145:classification* / Q000473:pathology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests