a Department of Biological Science and Technology , National Chiao Tung University , Taiwan.
b Cognitive Neuroscience Laboratory , Institute of Linguistics , Academia Sinica , Taiwan.
Aging Ment Health. 2019 Jul;23(7):831-839. doi: 10.1080/13607863.2018.1455804. Epub 2018 Apr 10.
Alterations in brain structure are viewed as neurobiological indicators which are closely tied to cognitive changes in healthy human aging. The current study used diffusion tensor imaging (DTI) tractography to investigate the relationship between age, brain variation in white matter (WM) integrity, and cognitive function. Sixteen younger adults (aged 20-28 years) and 18 healthy older adults (aged 60-75 years) underwent DTI scanning and a standardized battery of neuropsychological measures. Behaviorally, older adults exhibited poorer performance on multiple cognitive measures compared to younger adults. At the neural level, the effects of aging on theWM integrity were evident within interhemispheric (the anterior portion of corpus callosum) and transverse (the right uncinate fasciculus) fibers of the frontal regions, and the cingulum-angular fibers. Our correlation results showed that age-related WM differentially influenced cognitive function, with increased fractional anisotropy values in both the anterior corpus callosum and the right cingulum/angular fibers positively correlated with performance on the visuospatial task in older adults. Moreover, mediation analysis further revealed that the WM tract integrity of the frontal interhemspheric fibers was a significant mediator of age-visuospatial performance relation in older adults, but not in younger adults. These findings support the vulnerability of the frontal WM fibers to normal aging and push forward our understanding of cognitive aging by providing a more integrative view of the neural basis of linkages among aging, cognition, and brain.
大脑结构的改变被视为与健康人类衰老过程中的认知变化密切相关的神经生物学指标。本研究使用弥散张量成像（DTI）纤维束追踪技术来研究年龄、大脑白质（WM）完整性的变化与认知功能之间的关系。16 名年轻成年人（年龄 20-28 岁）和 18 名健康老年人（年龄 60-75 岁）接受了 DTI 扫描和标准化的神经心理学测试。行为上，与年轻成年人相比，老年人在多项认知测试中表现较差。在神经水平上，衰老对 WM 完整性的影响在额区的半球间（胼胝体前部）和横断（右侧钩束）纤维以及扣带-角回纤维中是明显的。我们的相关结果表明，与年龄相关的 WM 会对认知功能产生差异影响，在前胼胝体和右侧扣带/角回纤维中的分数各向异性值增加与老年人的视觉空间任务表现呈正相关。此外，中介分析进一步表明，老年人额间半球纤维的 WM 束完整性是年龄与视觉空间表现关系的重要中介，而在年轻成年人中则不是。这些发现支持了额叶 WM 纤维对正常衰老的脆弱性，并通过提供更综合的衰老、认知和大脑之间联系的神经基础观点，推动了我们对认知衰老的理解。
