Disrupted balance of long and short-range functional connectivity density in Alzheimer's disease (AD) and mild cognitive impairment (MCI) patients: a resting-state fMRI study

Yanping Mao; Zhengluan Liao; Xiaozheng Liu; Ting Li; Jiaojiao Hu; Dansheng Le; Yangliu Pei; Wangdi Sun; Jixin Lin; Yaju Qiu; Junpeng Zhu; Yan Chen; Chang Qi; Heng Su; Enyan Yu

doi:10.21037/atm-20-7019

Disrupted balance of long and short-range functional connectivity density in Alzheimer's disease (AD) and mild cognitive impairment (MCI) patients: a resting-state fMRI study

Ann Transl Med. 2021 Jan;9(1):65. doi: 10.21037/atm-20-7019.

Authors

Yanping Mao¹, Zhengluan Liao², Xiaozheng Liu³, Ting Li⁴, Jiaojiao Hu¹, Dansheng Le⁵, Yangliu Pei⁶, Wangdi Sun⁵, Jixin Lin⁷, Yaju Qiu², Junpeng Zhu², Yan Chen², Chang Qi², Heng Su², Enyan Yu¹

Affiliations

¹ Department of Clinical Psychology, Cancer Hospital of the University of Chinese Academy of Sciences, Zhejiang Cancer Hospital, Hangzhou, China.
² Department of Psychiatry, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, China.
³ Department of Radiology of the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China.
⁴ Medical Department, Qingdao University, Qingdao, China.
⁵ The Second school of Medical, Zhejiang Chinese Medical University, Hangzhou, China.
⁶ Graduate Department, Bengbu Medical College, Bengbu, China.
⁷ Department of Internal Medicine, Shengsi County People's Hospital, Zhoushan, China.

Abstract

Background: Alzheimer's disease (AD) is an age-progressive neurodegenerative disorder that affects cognitive function. There have been several functional connectivity (FC) strengths; however, FC density needs more development in AD. Therefore, this study wanted to determine the alternations in resting-state functional connectivity density (FCD) induced by Alzheimer's and mild cognitive impairment (MCI).

Methods: One hundred and eleven AD patients, 29 MCI patients, and 73 healthy controls (age- and sex-matched) were recruited and assessed using resting-state functional magnetic resonance imaging (MRI) scanning. The ultra-fast graph theory called FCD mapping was used to calculate the voxel-wise short- and long-range FCD values of the brain. We performed voxel-based between-group comparisons of FCD values to show the cerebral regions with significant FCD alterations. We performed Pearson's correlation analyses between aberrant functional connectivity densities and several clinical variables with adjustment for age and sex.

Results: Patients with cognition decline showed significantly abnormal long-range FCD in the cerebellum crus I, right insula, left inferior frontal gyrus, left superior frontal gyrus, left inferior frontal gyrus, and right middle frontal gyrus. The short-range FCD changed in the cerebellum crus I, left inferior frontal gyrus, left superior occipital gyrus, and right middle frontal gyrus. The long- and short-range functional connectivity in the left inferior frontal gyrus was positively correlated with Mini-mental State Examination (MMSE) scores.

Conclusions: FCD in the identified regions reflects mechanism and compensation for loss of cognitive function. These findings could improve the pathology of AD and MCI and supply a neuroimaging marker for AD and MCI.

Keywords: Alzheimer’s disease (AD); Functional connectivity density (FCD); mild cognitive impairment (MCI).