경도 인지 장애와 알츠하이머 환자에 대한 디폴트 모드 네트워크의 양적, 질적인 분석

Abstract

Functional magnetic resonance imaging, which measures blood oxygen level- dependent signal, has been suggested as a useful tool in the study of mild cognitive impairment (MCI) and Alzheimer`s disease (AD). Especially, analysis of default mode network (DMN) during the resting-state is widely used because of its simplicity, in particular, patients of AD, MCI. The purpose of our study was to examine effects of specific masking procedure during analysis of DMN in MCI and AD. As a result, we examined functional connectivity, especially DMN, qualitative and quantitative changes in patients with AD, MCI. To show this effects, we performed both whole brain analysis and specific masking analysis using DMN mask including both two group maps through the logical “AND” operation. 57 healthy elderly normal subjects, 34 elderly MCI patients, and 37 elderly AD patients were scanned for this study. One sample t-test results are consistent with previous studies. The qualitatively decreased activity in patient DMN was detected in left posterior cingulate cortex (PCC), right inferior parietal lobule (IPL), middle temporal gyrus. On the contrary, increased functional activity was observed in patient DMN in the right (MCI) and left (AD) frontal cortex. However, the quantitatively decreased activity in patient DMN was restricted to the left PCC (AD) and right IPL (AD, MCI). The quantitatively increased activity was not detected. These finding suggest that increase activities in right (MCI) and left (AD) frontal regions (qualitative changes) compensate for loss of function in left PCC and right IPL (quantitative changes). And it is important to look with quantitative and qualitative changes together because the difference between quantitative and qualitative analysis is a sensitive and important issue.