Temporoparietal MR imaging measures of atrophy in subjects with mild cognitive impairment that predict subsequent diagnosis of Alzheimer disease.
OBJECTIVE
Mild cognitive impairment (MCI) represents a transitional state between normal aging and Alzheimer disease (AD). Our goal was to determine if specific temporoparietal regions can predict the time to progress from MCI to AD.


METHODS
MR images from 129 individuals with MCI were analyzed to identify the volume of 14 neocortical and 2 non-neocortical brain regions, comprising the temporal and parietal lobes. In addition, 3 neuropsychological test scores were included to determine whether they would provide independent information. After a mean follow-up time of 5 years, 44 of these individuals had progressed to a diagnosis of AD.


RESULTS
Cox proportional hazards models demonstrated significant effects for 6 MR imaging regions with the greatest differences being the following: the entorhinal cortex (hazard ratio [HR] = 0.54, P < .001), inferior parietal lobule (hazard ratio [HR] = 0.64, P < .005), and middle temporal gyrus (HR = 0.64, P < .004), indicating decreased risk with larger volumes. A multivariable model showed that a combination of the entorhinal cortex (HR = 0.60, P < .001) and the inferior parietal lobule (HR = 0.62, P < .01) was the best predictor of time to progress to AD. A multivariable model reiterated the importance of including both MR imaging and neuropsychological variables in the final model.


CONCLUSIONS
These findings reaffirm the importance of the entorhinal cortex and present evidence for the importance of the inferior parietal lobule as a predictor of time to progress from MCI to AD. The inclusion of neuropsychological performance in the final model continues to highlight the importance of using these measures in a complementary fashion.
Desikan
R S
RS
Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA 02118, USA.
Cabral
H J
HJ
Fischl
B
B
Guttmann
C R G
CR
Blacker
D
D
Hyman
B T
BT
Albert
M S
MS
Killiany
R J
RJ
D000368:Aged; D000544:Alzheimer Disease / Q000453:epidemiology / Q000473:pathology*; D001284:Atrophy; D003072:Cognition Disorders / Q000453:epidemiology / Q000473:pathology*; D018728:Entorhinal Cortex / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000473:pathology*; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012307:Risk Factors; D012720:Severity of Illness Index; D013702:Temporal Lobe / Q000473:pathology*