Salminen Lauren E, Conturo Thomas E, Laidlaw David H, Cabeen Ryan P, Akbudak Erbil, Lane Elizabeth M, Heaps Jodi M, Bolzenius Jacob D, Baker Laurie M, Cooley Sarah, Scott Staci, Cagle Lee M, Phillips Sarah, Paul Robert H
Department of Psychology, University of Missouri- Saint Louis, 1 University Boulevard, Stadler Hall 442 A, Saint Louis, MO, 63121, USA.
Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway, St. Louis, MO, 63110, USA.
Brain Imaging Behav. 2016 Mar;10(1):203-11. doi: 10.1007/s11682-015-9383-7.
Aging is associated with microstructural changes in brain tissue that can be visualized using diffusion tensor imaging (DTI). While previous studies have established age-related changes in white matter (WM) diffusion using DTI, the impact of age on gray matter (GM) diffusion remains unclear. The present study utilized DTI metrics of mean diffusivity (MD) to identify age differences in GM/WM microstructure in a sample of healthy older adults (N = 60). A secondary aim was to determine the functional significance of whole-brain GM/WM MD on global cognitive function using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Participants were divided into three age brackets (ages 50-59, 60-69, and 70+) to examine differences in MD and cognition by decade. MD was examined bilaterally in the frontal, temporal, parietal, and occipital lobes for the primary analyses and an aggregate measure of whole-brain MD was used to test relationships with cognition. Significantly higher MD was observed in bilateral GM of the temporal and parietal lobes, and in right hemisphere WM of the frontal and temporal lobes of older individuals. The most robust differences in MD were between the 50-59 and 70+ age groups. Higher whole-brain GM MD was associated with poorer RBANS performance in the 60-69 age group. Results suggest that aging has a significant and differential impact on GM/WM diffusion in healthy older adults, which may explain a modest degree of cognitive variability at specific time points during older adulthood.
衰老与脑组织的微观结构变化相关，这些变化可通过扩散张量成像（DTI）可视化。虽然先前的研究已利用DTI确定了白质（WM）扩散中与年龄相关的变化，但年龄对灰质（GM）扩散的影响仍不明确。本研究利用平均扩散率（MD）的DTI指标，在一组健康老年人样本（N = 60）中确定GM/WM微观结构的年龄差异。第二个目的是使用可重复神经心理状态评估量表（RBANS）确定全脑GM/WM MD对整体认知功能的功能意义。参与者被分为三个年龄组（50 - 59岁、60 - 69岁和70岁以上），以按十年为单位检查MD和认知的差异。在额叶、颞叶、顶叶和枕叶双侧检查MD进行主要分析，并使用全脑MD的综合测量来测试与认知的关系。在老年人的颞叶和顶叶双侧GM以及额叶和颞叶右半球WM中观察到MD显著更高。MD最显著的差异出现在50 - 59岁和70岁以上年龄组之间。在60 - 69岁年龄组中，较高的全脑GM MD与较差的RBANS表现相关。结果表明，衰老对健康老年人的GM/WM扩散有显著且不同的影响，这可能解释了成年后期特定时间点认知变异性的适度程度。
