Boban Jasmina, Thurnher Majda M, Boban Nikola, Law Meng, Jahanshad Neda, Nir Talia M, Lendak Dajana F, Kozic Dusko
Faculty of Medicine Novi Sad, Department of Radiology, University of Novi Sad, Novi Sad, Serbia.
Vojvodina Institute of Oncology, Center for Diagnostic Imaging, Sremska Kamenica, Serbia.
Front Neurol. 2022 Jun 2;13:870909. doi: 10.3389/fneur.2022.870909. eCollection 2022.
The current concept of brain aging proposes three gradient patterns of changes in white matter that occur during healthy brain aging: antero-posterior, supero-inferior, and the myelodegeneration-retrogenesis (or the "last-in-first-out") concept. The aim of this study was to correlate white matter diffusivity measures (fractional anisotropy-FA, mean diffusivity-MD, radial diffusivity-RD, and axial diffusivity-AD) in healthy volunteers with chronological age and education level, in order to potentially incorporate the findings with proposed patterns of physiological brain aging. The study was performed on 75 healthy participants of both sexes, with an average age of 37.32 ± 11.91 years underwent brain magnetic resonance imaging (MRI) with diffusion tensor imaging (DTI). DTI was performed using tract-based spatial statistics (TBSS), with the analysis of four parameters: FA, MD, RD, and AD. Skeletonized measures were averaged in 29 regions of interest in white matter. Correlations between age and DTI measures and between education-level and DTI measures were performed using Pearson's correlation test. To correct for multiple comparisons, we applied a Bonferroni correction to the -values. Significance was set at ≤ . A significant negative correlation of FA with age was observed in posterior thalamic radiation (PTR) (< ). A significant positive correlation between age and MD was observed in sagittal stratum (SS) (< ), between age and RD in PTR, SS, and retrolenticular internal capsule (< ), and between age and AD in the body of the corpus callosum (< ). There were no significant correlations of DTI parameters with educational level. According to our study, RD showed the richest correlations with age, out of all DTI metrics. FA, MD, and RD showed significant changes in the diffusivity of projection fibers, while AD presented diffusivity changes in the commissural fibers. The observed heterogeneity in diffusivity changes across the brain cannot be explained by a single aging gradient pattern, since it seems that different patterns of degradation are true for different fiber tracts that no currently available theory can globally explain age-related changes in the brain. Additional factors, such as the effect of somatosensory decline, should be included as one of the important covariables to the existing patterns.
前后模式、上下模式以及髓鞘退变-逆行发生（即“后进先出”）概念。本研究的目的是将健康志愿者的白质扩散率测量值（分数各向异性-FA、平均扩散率-MD、径向扩散率-RD和轴向扩散率-AD）与实际年龄和教育水平相关联，以便有可能将这些发现与所提出的生理性脑老化模式相结合。该研究对75名健康参与者（男女均有）进行，这些参与者平均年龄为37.32±11.91岁，接受了带有扩散张量成像（DTI）的脑磁共振成像（MRI）检查。DTI采用基于纤维束的空间统计学（TBSS）进行，分析四个参数：FA、MD、RD和AD。在白质的29个感兴趣区域对骨骼化测量值进行平均。使用Pearson相关检验对年龄与DTI测量值之间以及教育水平与DTI测量值之间进行相关性分析。为校正多重比较，我们对p值应用了Bonferroni校正。显著性设定为p≤0.05。在丘脑后辐射（PTR）中观察到FA与年龄呈显著负相关（p<0.05）。在矢状层（SS）中观察到年龄与MD呈显著正相关（p<0.05），在PTR、SS和豆状核后内囊中年龄与RD呈显著正相关（p<0.05），在胼胝体体部年龄与AD呈显著正相关（p<0.05）。DTI参数与教育水平之间无显著相关性。根据我们的研究，在所有DTI指标中，RD与年龄的相关性最为丰富。FA、MD和RD在投射纤维的扩散率方面表现出显著变化，而AD在连合纤维的扩散率方面呈现变化。整个大脑中观察到的扩散率变化的异质性无法用单一的老化梯度模式来解释，因为似乎不同的纤维束存在不同的退化模式，目前尚无理论能够全面解释大脑中与年龄相关的变化。诸如躯体感觉衰退的影响等其他因素应作为现有模式的重要协变量之一纳入考虑。
