Subcortical Vascular Versus Amnestic Mild Cognitive Impairment: Comparison of Cerebral Glucose Metabolism

Background And Purpose: Most studies on mild cognitive impairment (MCI) have been focused on amnestic MCI (aMCI) that is the preclinical stage of Alzheimer's disease (AD). In contrast, only a few studies have involved patients in the preclinical stages of subcortical vascular dementia (subcortical vascular MCI, svMCI). We tried to compare the overall glucose metabolism in patients with svMCI with that of patients with aMCI.

Methods: We compared the regional metabolic patterns shown on 18 F-FDG (fluro deoxy glucose) positron emission tomography (PET) images from 18 patients with svMCI with those from 25 aMCI patients matched for age, sex, education, and mini-mental state examination (MMSE) score and with those from 35 healthy subjects using a voxel-wise analysis. SPM 2 was used for statistical analysis.

Results: Relative to normal controls, the hypometabolic regions in the aMCI patients were in the bilateral parahippocampal, bilateral posterior cingulate, left superior temporal gyri, left inferior parietal lobule, and right inferior frontal gyrus while those in the svMCI patients were located in the thalamus, insula, superior temporal gyrus, anterior cingulate gyrus, cingulum, right basal ganglia, cerebellum, and brainstem. A direct comparison of glucose metabolism between svMCI and aMCI showed that the glucose hypometabolism in patients with svMCI was more severe in the thalamus, brainstem, and cerebellum.

Conclusion: Our study suggested that svMCI was distinct from aMCI in terms of neuropsychological and PET findings, which may explain their clinical manifestations.