Unlocking the enigma: unraveling multiple cognitive dysfunction linked to glymphatic impairment in early Alzheimer's disease

Jiayi Zhong; Xiaochen Zhang; Huanyu Xu; Xiaoran Zheng; Luyao Wang; Jiehui Jiang; Yunxia Li

doi:10.3389/fnins.2023.1222857

Unlocking the enigma: unraveling multiple cognitive dysfunction linked to glymphatic impairment in early Alzheimer's disease

Front Neurosci. 2023 Jul 21:17:1222857. doi: 10.3389/fnins.2023.1222857. eCollection 2023.

Authors

Jiayi Zhong¹, Xiaochen Zhang², Huanyu Xu³, Xiaoran Zheng², Luyao Wang¹, Jiehui Jiang⁴, Yunxia Li²

Affiliations

¹ School of Life Science, Shanghai University, Shanghai, China.
² Department of Neurology, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China.
³ School of Communication and Information Engineering, Shanghai University, Shanghai, China.
⁴ Institute of Biomedical Engineering, Shanghai University, Shanghai, China.

Abstract

Background: Alzheimer's disease (AD) is one of the world's well-known neurodegenerative diseases, which is related to the balance mechanism of production and clearance of two proteins (amyloid-β and tau) regulated by the glymphatic system. Latest studies have found that AD patients exhibit impairments to their glymphatic system. However, the alterations in the AD disease continuum, especially in the early stages, remain unclear. Moreover, the relationship between the glymphatic system and cognitive dysfunction is still worth exploring.

Methods: A novel diffusion tensor image analysis method was applied to evaluate the activity of the glymphatic system by an index for diffusivity along the perivascular space (ALPS-index). Based on this method, the activity of the glymphatic system was noninvasively evaluated in 300 subjects, including 111 normal controls (NC), 120 subjects with mild cognitive impairment (MCI), and 69 subjects with AD. Partial correlation analysis was applied to explore the association between glymphatic system and cognitive impairment based on three domain-general scales and several domain-specific cognitive scales. Receiver operating characteristic curve analysis was used to evaluate the classification performance of ALPS-index along the AD continuum.

Results: ALPS-index was significantly different among NC, MCI and AD groups, and ALPS-index decreased with cognitive decline. In addition, ALPS-index was significantly correlated with the scores of the clinical scales (p<0.05, FDR corrected), especially in left hemisphere. Furthermore, combination of ALPS and fractional anisotropy (FA) values achieved better classification results (NC vs. MCI: AUC = 0.6610, NC vs. AD: AUC = 0.8214).

Conclusion: Here, we show that the glymphatic system is closely associated with multiple cognitive dysfunctions, and ALPS-index can be used as a biomarker for alterations along the AD continuum. This may provide new targets and strategies for the treatment of AD, and has the potential to assist clinical diagnosis.

Keywords: Alzheimer’s disease; classification; clinical dementia rating scale; cognitive dysfunction; diffusion tensor imaging; glymphatic system; medical image processing; mild cognitive impairment.