Mild cognitive impairment and Alzheimer disease: regional diffusivity of water.
OBJECTIVE
To compare the regional diffusivity of water in the brains of normally aging elderly people and patients with mild cognitive impairment (MCI) or Alzheimer disease.


METHODS
Magnetic resonance images were obtained in 21 patients with Alzheimer disease, 19 patients with MCI, and 55 normally aging elderly control subjects without evidence of cognitive impairment. Regions of interest were drawn to compare the apparent diffusion coefficient (ADC) and the anisotropy index (AI) in frontal, parietal, temporal, occipital, anterior, and posterior cingulate white matter (WM), and the thalami and hippocampi.


RESULTS
Hippocampal ADC was higher in MCI and Alzheimer disease patients than in control subjects. ADC of the temporal stem and posterior cingulate, occipital, and parietal WM was higher in Alzheimer disease patients than in control subjects. Except for occipital AI, which was lower in MCI patients than in control subjects, there were no differences in AI among the three groups for any of the regions.


CONCLUSIONS
Hippocampal ADC was significantly different between control subjects and MCI patients, many of whom likely have preclinical Alzheimer disease. Elevation in hippocampal ADC may reflect early ultrastructural changes in the progression of Alzheimer disease.
Department of Diagnostic Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA.
K
K
Kantarci
C R
CR
Jack
Y C
YC
Xu
N G
NG
Campeau
P C
PC
O'Brien
G E
GE
Smith
R J
RJ
Ivnik
B F
BF
Boeve
E
E
Kokmen
E G
EG
Tangalos
R C
RC
Petersen
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis*; D000647:Amnesia / Q000175:diagnosis*; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D002540:Cerebral Cortex / Q000473:pathology; D004058:Diffusion; D005260:Female; D006179:Gyrus Cinguli / Q000473:pathology; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012016:Reference Values; D012680:Sensitivity and Specificity; D013788:Thalamus / Q000473:pathology