Differences in functional brain connectivity alterations associated with cerebral amyloid deposition in amnestic mild cognitive impairment

Dahyun Yi; Young Min Choe; Min Soo Byun; Bo Kyung Sohn; Eun Hyun Seo; Jiyoung Han; Jinsick Park; Jong Inn Woo; Dong Young Lee

doi:10.3389/fnagi.2015.00015

Differences in functional brain connectivity alterations associated with cerebral amyloid deposition in amnestic mild cognitive impairment

Front Aging Neurosci. 2015 Feb 19:7:15. doi: 10.3389/fnagi.2015.00015. eCollection 2015.

Authors

Dahyun Yi¹, Young Min Choe¹, Min Soo Byun¹, Bo Kyung Sohn², Eun Hyun Seo³, Jiyoung Han¹, Jinsick Park⁴, Jong Inn Woo¹, Dong Young Lee¹

Affiliations

¹ Department of Neuropsychiatry, Clinical Research Institute, Seoul National University Hospital , Seoul , South Korea.
² Department of Neuropsychiatry, Seoul Metropolitan Boramae Medical Center , Seoul , South Korea.
³ Division of Natural Medical Sciences, College of Health Science, Chosun University , Gwangju , South Korea.
⁴ Department of Biomedical Engineering, Hanyang University , Seoul , South Korea.

Abstract

Despite potential implications for the early detection of impending Alzheimer's disease (AD), very little is known about the differences of large-scale brain networks between amnestic mild cognitive impairment (aMCI) with high cerebral amyloid-beta protein (Aβ) deposition (i.e., aMCI+) and aMCI with no or very little Aβ deposition (i.e., aMCI-). We first aimed to extend the current literature on altering intrinsic functional connectivity (FC) of the default mode network (DMN) and salience network (SN) from cognitively normal (CN) to AD dementia. Second, we further examined the differences of the DMN and the SN between aMCI-, aMCI+, and CN. Forty-three older adult (12 CN, 10 aMCI+, 10 aMCI-, and 11 AD dementia) subjects were included. All participants received comprehensive clinical and neuropsychological assessment, resting-state functional magnetic resonance imaging, structural MRI, and Pittsburgh compound-B-PET scans. FC data were preprocessed using multivariate exploratory linear optimized decomposition into independent components of FMRIB's Software Library. Group comparisons were carried out using the "dual-regression" approach. In addition, to verify presence of gray matter volume changes with intrinsic functional network alterations, voxel-based morphometry was performed on the acquired T1-weighted data. As expected, AD dementia participants exhibited decreased FC in the DMN compared to CN (particularly in the precuneus and cingulate gyrus). The degree of alteration in the DMN in aMCI+ compared to CN was intermediate to that of AD. In contrast, aMCI- exhibited increased FC in the DMN compared to CN (primarily in the precuneus) as well as aMCI+. In terms of the SN, aMCI- exhibited decreased FC compared to both CN and aMCI+ particularly in the inferior frontal gyrus. FC within the SN in aMCI+ and AD did not differ from CN. Compared to CN, aMCI- showed atrophy in bilateral superior temporal gyri whereas aMCI+ showed atrophy in right precuneus. The results indicate that despite the similarity in cross-sectional cognitive features, aMCI- has quite different functional brain connectivity compared to aMCI+.

Keywords: amnestic mild cognitive impairment; amyloid-beta deposition; brain functional connectivity; default mode network; salience network.