The Conjoint Analysis of Microstructural and Morphological Changes of Gray Matter During Aging.

Xin Zhao,Hongyan Ni,Xizi Song,Qiong Wu,Yuanyuan Chen,Dong Ming

doi:10.3389/fneur.2019.00184

Abstract

Macromorphological and microstructural changes of gray matter (GM) happen during brain normal aging. However, the mechanism of macro-microstructure association is still unclear, which is of guidance for understanding many neurodegenerative diseases. In this study, adopting structural magnetic resonance imaging (sMRI) and diffusion kurtosis imaging (DKI), GM aging pattern was characterized and its macro-microstructure associations were revealed. For 60 subjects among the ages of 47–79, the DKI and T1-weighted images were investigated with voxel-based analysis. The results showed age-related overlapped patterns between morphological and microstructural alterations during normal aging. It was worth noting that morphological changes and mean diffusivity (MD) indexes abnormalities mainly overlapped in the following regions, superior frontal gyrus, inferior frontal gyrus, cingulum gyrus, superior temporal gyrus, insula, and thalamus. Besides, overlapped with GM atrophies, mean kurtosis (MK) abnormalities were observed in superior frontal gyrus, inferior frontal gyrus, transverse temporal gyrus, insula, and thalamus. What important was that intrinsic aging independent associations between macrostructure and microstructure were found especially in media superior frontal gyrus, which revealed the potential mechanisms in the process of aging. The physiological mechanism may be associated with the elimination of neurons and synapses and the shrinkage of large neurons. Understanding the associations of GM volume changes and microstructural changes can account for the underlying mechanisms of aging and age-related neurodegenerative diseases.

Highlights

Normal aging is an irreversible and uncontrollable process, with a rapid increasing population in recent years
All magnetic resonance imaging (MRI) data used in this study were obtained from the Tianjin First Central Hospital, China, which was approved by the ethics committee
The results can be summarized into two aspects: [1] the morphological and microstructural measures significantly altered with aging and overlapped in some regions especially bilateral medial superior frontal gyrus

Summary

Introduction

Normal aging is an irreversible and uncontrollable process, with a rapid increasing population in recent years. It’s a common knowledge that the cognitive function gradually declines during normal aging, including memory [1], language [2], and motor control [3]. The impact of cognitive function decline on the elderly is not fatal, it does cause inconvenience in the daily life. What’ more, many studies have reported that some neurodegenerative diseases occurred with advanced age, such as Alzheimer’s disease [4], Parkinson’s disease [5] and Multiple Sclerosis disease [6]. It’s commonly accepted that the function decline is due to the widely degeneration of brain structure, including both microstructural and morphological changes [7,8,9].

Methods

Results

Discussion

Conclusion