Amnestic Mild Cognitive Impairment: Structural MR Imaging Findings Predictive of Conversion to Alzheimer Disease

G Karas,W Van Der Flier,N Fox,P Scheltens,F Barkhof,J Sluimer,H Vrenken,S.A.R.B Rombouts,R Goekoop

doi:10.3174/ajnr.a0949

Abstract

Mild cognitive impairment (MCI) is considered by many to be a prodromal phase of Alzheimer disease (AD). We used voxel-based morphometry (VBM) to find out whether structural differences on MR imaging could offer insight into the development of clinical AD in patients with amnestic MCI at 3-year follow-up. Twenty-four amnestic patients with MCI were included. After 3 years, 46% had progressed to AD (n = 11; age, 72.7 +/- 4.8 years; women/men, 8/3). For 13 patients (age, 72.4 +/- 8.6 years; women/men, 10/3), the diagnosis remained MCI. Baseline MR imaging at 1.5T included a coronal heavily T1-weighted 3D gradient-echo sequence. Localized gray matter differences were assessed with VBM. The converters had less gray matter volume in medial (including the hippocampus) and lateral temporal lobe, parietal lobe, and lateral temporal lobe structures. After correction for age, sex, total gray matter volume, and neuropsychological evaluation, left-sided atrophy remained statistically significant. Specifically, converters had more left parietal atrophy (angular gyrus and inferior parietal lobule) and left lateral temporal lobe atrophy (superior and middle temporal gyrus) than stable patients with MCI. By studying 2 MCI populations, converters versus nonconverters, we found atrophy beyond the medial temporal lobe to be characteristic of patients with MCI who will progress to dementia. Atrophy of structures such as the left lateral temporal lobe and left parietal cortex may independently predict conversion.

Highlights

AND PURPOSE: Mild cognitive impairment (MCI) is considered by many to be a prodromal phase of Alzheimer disease (AD)
By studying 2 MCI populations, converters versus nonconverters, we found atrophy beyond the medial temporal lobe to be characteristic of patients with MCI who will progress to dementia
The term “mild cognitive impairment” (MCI) was coined to describe individuals not yet fulfilling the criteria of Alzheimer disease (AD) but who do not have a normal cognitive profile compared with their contemporaries.[1]

Summary

Methods

Twenty-four amnestic patients with MCI were included. After 3 years, 46% had progressed to AD (n ϭ 11; age, 72.7 Ϯ 4.8 years; women/men, 8/3). For 13 patients (age, 72.4 Ϯ 8.6 years; women/men, 10/3), the diagnosis remained MCI. Patients with MCI were diagnosed according to the Petersen criteria, with a slowly progressive memory decline, without the involvement of another domain of cognitive function, that did not interfere significantly with activities of daily living.[2] Inclusion of an individual in the study required a MiniMental State Examination (MMSE) score of 24 and higher.[12] The follow-up ending for this study was set at 3 years after inclusion, and diagnosis of AD was made according to the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer’s Disease and Related Disorders Association (NINCDS-ARDRA) criteria.[13] All patients received a diagnostic battery comprising the MMSE,[12] clinical dementia rating (CDR),[14] and New York University (NYU) paragraph recall tests, which were used for cognitive profiling. All patients provided informed consent according to the Declaration of Helsinki under

Results

Discussion

Conclusion