Locus coeruleus (LC) and substantia nigra pars compacta (SNpc) degrade with normal aging, but not much is known regarding how these changes manifest in MRI images, or whether these markers predict aspects of cognition. Here, we use high-resolution diffusion-weighted MRI to investigate microstructural and compositional changes in LC and SNpc in young and older adult cohorts, as well as their relationship with cognition. In LC, the older cohort exhibited a significant reduction in mean and radial diffusivity, but a significant increase in fractional anisotropy compared with the young cohort. We observed a significant correlation between the decrease in LC mean, axial, and radial diffusivities and measures examining cognition (Rey Auditory Verbal Learning Test delayed recall) in the older adult cohort. This observation suggests that LC is involved in retaining cognitive abilities. In addition, we observed that iron deposition in SNpc occurs early in life and continues during normal aging.

中文翻译：

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蓝斑和黑质致密部年龄相关微结构变化的表征

蓝斑 (LC) 和黑质致密部 (SNpc) 会随着正常衰老而退化，但关于这些变化如何在 MRI 图像中表现出来，或者这些标记是否能预测认知的各个方面，我们知之甚少。在这里，我们使用高分辨率弥散加权 MRI 来研究年轻和年长成人队列中 LC 和 SNpc 的微观结构和组成变化，以及它们与认知的关系。在 LC 中，与年轻队列相比，年长队列的平均和径向扩散率显着降低，但分数各向异性显着增加。我们观察到老年人群中 LC 平均、轴向和径向扩散率的降低与检查认知的措施（雷伊听觉语言学习测试延迟回忆）之间存在显着相关性。这一观察结果表明 LC 与保持认知能力有关。此外，我们观察到 SNpc 中的铁沉积发生在生命的早期，并在正常老化过程中继续存在。