Abnormal Resting-State Functional Connectivity Strength in Mild Cognitive Impairment and Its Conversion to Alzheimer's Disease.

Ying Han,Xuanyu Li,Bin Jing,Yuxia Li,Yu Sun,Guanqun Chen,Kuncheng Li,Yang Yu,Defeng Wang,Yongqiu Li,Can Sheng,Xiaoni Wang,Hongyan Li,Xiaochen Hu,Frank Jessen,Mingrui Xia

doi:10.1155/2016/4680972

Abstract

Individuals diagnosed with mild cognitive impairment (MCI) are at high risk of transition to Alzheimer's disease (AD). However, little is known about functional characteristics of the conversion from MCI to AD. Resting-state functional magnetic resonance imaging was performed in 25 AD patients, 31 MCI patients, and 42 well-matched normal controls at baseline. Twenty-one of the 31 MCI patients converted to AD at approximately 24 months of follow-up. Functional connectivity strength (FCS) and seed-based functional connectivity analyses were used to assess the functional differences among the groups. Compared to controls, subjects with MCI and AD showed decreased FCS in the default-mode network and the occipital cortex. Importantly, the FCS of the left angular gyrus and middle occipital gyrus was significantly lower in MCI-converters as compared with MCI-nonconverters. Significantly decreased functional connectivity was found in MCI-converters compared to nonconverters between the left angular gyrus and bilateral inferior parietal lobules, dorsolateral prefrontal and lateral temporal cortices, and the left middle occipital gyrus and right middle occipital gyri. We demonstrated gradual but progressive functional changes during a median 2-year interval in patients converting from MCI to AD, which might serve as early indicators for the dysfunction and progression in the early stage of AD.

Highlights

Alzheimer’s disease (AD), an irreversible neurodegenerative disease characterized by memory dysfunction, executive function decline, and multiple cognitive domain impairments, is one of the most financially costly diseases [1]
We demonstrated gradual but progressive functional changes during a median 2-year interval in patients converting from mild cognitive impairment (MCI) to AD, which might serve as early indicators for the dysfunction and progression in the early stage of AD
After a mean follow-up period of 24 months, the MMSE and auditory verbal learning test- (AVLT-)I were significantly lower in the MCI-c group than in the MCI-nc group, and the AVLT-delayed recall (AVLT-D), AVLTdelayed recognition (AVLT-R), and Montreal Cognitive Assessment (MoCA) were marginally lower in the MCI-c group

Summary

Introduction

Alzheimer’s disease (AD), an irreversible neurodegenerative disease characterized by memory dysfunction, executive function decline, and multiple cognitive domain impairments, is one of the most financially costly diseases [1]. Considering the urgent requirement for the identification of those MCI patients who are most likely to undergo rapid progression and conversion to AD, it is of great significance to investigate and Neural Plasticity discover the potential biomarkers for the early identification of the dysfunction and progression in the early stage of AD. Investigations have yielded limited functional biomarkers that predict the progression from MCI to AD, except the consistent identification of the changes of resting-state functional connectivity (RSFC) of the defaultmode network (DMN) in AD [8, 9]. Deficits in RSFC are not confined to the DMN in patients with MCI converting to AD [10]. It is not clear whether other brain regions participate in the conversion to AD

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Conclusion