Abstract
Aim: Mild cognitive impairment (MCI) is considered to refer to a transitional zone between normal cognitive function and dementia. It comprises a heterogenous condition with a variety of clinical outcomes. The purpose of this study was to determine whether combined analysis of brain imaging studies, including MRI and single photon emission computed tomography (SPECT) , and assessment of awareness of memory deficits is useful in predicting Alzheimer disease (AD) in subjects with MCI.
Methods: Thirty-nine patients with amnestic MCI [21 patients who had developed AD (MCI/AD) and 18 patients who did not develop AD (MCI/MCI) during a 2.5 to 3-year follow-up] and 19 patients with early AD were included in the study. The entorhinal cortex z-score in each patient was calculated using voxel-based morphometry with 3D T1-weighted MRI (software: VSRAD) . SPECT data were analyzed by the three-dimensional stereotactic surface projection method and posterior cortical hypoperfusion was qualitatively assessed. Awareness of memory deficits was evaluated with a standardized memory questionnaire system based on the Everyday Memory Checklist (EMC) . The discrepancy between these scores (caregiver rating-patient rating) was analyzed.
Results: The MCI/AD group showed a tendency toward higher z-scores in the entorhinal cortex on MRI scan, a significantly higher frequency of posterior hypoperfusion on SPECT scan, and significantly more impaired awareness of memory deficits than in the MCI/MCI group. These findings were more severe and more frequent in the AD group than in the MCI/AD and MCI/MCI groups. A combined study of MRI, SPECT, and awareness of memory deficits yielded a higher level of discrimination between MCI/AD and MCI/MCI group results than in each separate study.
Conclusion: A combined study of brain imagings (MRI and SPECT) and an assessment of awareness of memory deficits may improve the prediction of the development of AD in subjects with amnestic MCI.
