Abstract
Mild cognitive impairment (MCI) is a risk factor for Alzheimer disease and can be difficult to diagnose because of the subtlety of symptoms. This study attempted to examine gray matter (GM) and white matter (WM) changes with cortical thickness analysis and diffusion tensor imaging (DTI) in patients with MCI and demographically matched comparison subjects to test these measurements as possible imaging markers for diagnosis. Subjects with amnestic MCI (n = 10; age, 72.2 +/- 7.1 years) and normal cognition (n = 10; age, 70.1 +/- 7.7 years) underwent DTI and T1-weighted MR imaging at 3T. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), and cortical thickness were measured and compared between the MCI and control groups. We evaluated the diagnostic accuracy of 2 methods, either in combination or separately, using binary logistic regression and nonparametric statistical analyses for sensitivity, specificity, and accuracy. Decreased FA and increased ADC in WM regions of the frontal and temporal lobes and corpus callosum (CC) were observed in patients with MCI. Cortical thickness was decreased in GM regions of the frontal, temporal, and parietal lobes in patients with MCI. Changes in WM and cortical thickness seemed to be more pronounced in the left hemisphere compared with the right hemisphere. Furthermore, the combination of cortical thickness and DTI measurements in the left temporal areas improved the accuracy of differentiating MCI patients from control subjects compared with either measure alone. DTI and cortical thickness analyses may both serve as imaging markers to differentiate MCI from normal aging. Combined use of these 2 methods may improve the accuracy of MCI diagnosis.
Highlights
AND PURPOSE: Mild cognitive impairment (MCI) is a risk factor for Alzheimer disease and can be difficult to diagnose because of the subtlety of symptoms
diffusion tensor imaging (DTI) and cortical thickness analyses may both serve as imaging markers to differentiate MCI from normal aging
Mild cognitive impairment (MCI) is often a precursor to dementias such as Alzheimer disease (AD), with rates of progression estimated between 12% and 15% per year.[1,2,3,4]
Summary
Subjects with amnestic MCI (n ϭ 10; age, 72.2 Ϯ 7.1 years) and normal cognition (n ϭ 10; age, 70.1 Ϯ 7.7 years) underwent DTI and T1-weighted MR imaging at 3T. The patient group included 10 right-handed subjects who met the criteria for amnestic MCI (5 men, 5 women; age, 72.2 Ϯ 7.1 years; education, 15.2 Ϯ 4.1 years). The diagnosis of amnestic MCI was made by experienced neurologists (A.I.L., J.J.L.) on the basis of Petersen criteria,[2,3] including a subjective cognitive complaint (corroborated by an informant), impairment of memory with formal neuropsychologic testing (Ͼ Ϫ1.5 SD below the performance of age and education control subjects), normal general cognitive functioning, and preserved instrumental activities of daily living. Ten cognitively intact subjects were recruited from the community or from the Emory Alzheimer Disease Research Center (3 men, 7 women; age, 70.1 Ϯ 7.7 years; education, 14.0 Ϯ 4.0 years)
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