OBJECTIVE: Subgroups of mild cognitive impairment (MCI) have been proposed, but few studies have investigated the nonamnestic, single-domain subgroup of MCI. The goal of the study was to compare clinical and neuroimaging characteristics of two single-domain MCI subgroups: amnestic MCI and dysexecutive MCI. METHODS: We compared the cognitive, functional, behavioral, and brain imaging characteristics of patients with amnestic MCI (n = 26), patients with dysexecutive MCI (n = 32), and age- and education-matched control subjects (n = 36) using analysis of variance and chi(2) tests. We used voxel-based morphometry to examine group differences in brain magnetic resonance imaging atrophy patterns. RESULTS: Patients with dysexecutive MCI had significantly lower scores on the majority of executive function tests, increased behavioral symptoms, and left prefrontal cortex atrophy on magnetic resonance imaging when compared with control subjects. In contrast, patients with amnestic MCI had significantly lower scores on tests of memory and a pattern of atrophy including bilateral hippocampi and entorhinal cortex, right inferior parietal cortex, and posterior cingulate gyrus when compared with control subjects. INTERPRETATION: Overall, the clinical and neuroimaging findings provide support for two distinct single-domain subgroups of MCI, one involving executive function and the other involving memory. The brain imaging differences suggest that the two MCI subgroups have distinct patterns of brain atrophy.
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