Johnson Nathan F, Kim Chobok, Gold Brian T
Department of Anatomy and Neurobiology, University of Kentucky School of Medicine, Lexington, KY, 40536-0298, USA.
Age (Dordr). 2013 Dec;35(6):2045-56. doi: 10.1007/s11357-012-9493-8. Epub 2012 Nov 18.
Socioeconomic status (SES) is an important reserve variable which has been shown to benefit the aging brain's macrostructure. However, it remains unknown whether SES affects age-related changes in the brain's white matter (WM) microstructure. Here, we used diffusion tensor imaging to explore the relationship between SES and three components of the diffusion tensor [fractional anisotropy (FA), axial diffusivity, and radial diffusivity (DR)]. Participants were 40 (16 male) cognitively normal young adults (mean age = 33.3 years, SD = 4.27) and 44 (19 male) cognitively normal community dwelling seniors (mean age = 66.2 years, SD = 7.5). Age-related FA declines were observed across a large portion of the WM skeleton. However, seniors with high SES showed lower age-related WM integrity declines in three frontal tracts: the right anterior corona radiata and bilateral portions of WM underlying the superior frontal gyri (SFG-WM). Positive SES-FA correlations were primarily driven by negative DR-SES correlations, suggesting that SES may buffer age-related declines in myelin. The functional significance of high SES in these frontal tracts was demonstrated through positive correlations with working memory performance. Possible mechanisms through which SES may attenuate the effects of age on frontal WM integrity are discussed.
社会经济地位（SES）是一个重要的储备变量，已被证明对衰老大脑的宏观结构有益。然而，SES是否会影响大脑白质（WM）微观结构的年龄相关变化仍不清楚。在这里，我们使用扩散张量成像来探究SES与扩散张量的三个组成部分[分数各向异性（FA）、轴向扩散率和径向扩散率（DR）]之间的关系。参与者包括40名（16名男性）认知正常的年轻成年人（平均年龄 = 33.3岁，标准差 = 4.27）和44名（19名男性）认知正常的社区居住老年人（平均年龄 = 66.2岁，标准差 = 7.5）。在大部分WM骨架中观察到与年龄相关的FA下降。然而，高SES的老年人在三个额叶束中显示出与年龄相关的WM完整性下降较低：右侧前放射冠以及额上回下方WM的双侧部分（SFG-WM）。SES与FA的正相关主要由DR与SES的负相关驱动，这表明SES可能缓冲与年龄相关的髓鞘减少。通过与工作记忆表现的正相关证明了高SES在这些额叶束中的功能意义。我们还讨论了SES可能减弱年龄对额叶WM完整性影响的潜在机制。
