Department of Psychology, University of Arizona, Tucson, United States of America; Department of Neurology, University of Arizona, Tucson, United States of America; McKnight Brain Research Institute, University of Arizona, Tucson, United States of America; BIO5 Institute, University of Arizona, Tucson, United States of America.
Department of Psychology, University of Arizona, Tucson, United States of America.
Exp Gerontol. 2021 May;147:111258. doi: 10.1016/j.exger.2021.111258. Epub 2021 Jan 28.
Many believe that the circadian impairments associated with aging and Alzheimer's disease are, simply enough, a byproduct of tissue degeneration within the central pacemaker, the suprachiasmatic nucleus (SCN). However, the findings that have accumulated to date examining the SCNs obtained postmortem from the brains of older individuals, or those diagnosed with Alzheimer's disease upon autopsy, suggest only limited atrophy. We review this literature as well as a complementary one concerning fetal-donor SCN transplant, which established that many circadian timekeeping functions can be maintained with rudimentary (structurally limited) representations of the SCN. Together, these corpora of data suggest that the SCN is a resilient brain region that cannot be directly (or solely) implicated in the behavioral manifestations of circadian disorganization often witnessed during aging as well as early and late progression of Alzheimer's disease. We complete our review by suggesting future directions of research that may bridge this conceptual divide and briefly discuss the implications of it for improving health outcomes in later adulthood.
许多人认为，与衰老和阿尔茨海默病相关的昼夜节律障碍，简单来说，就是中枢起搏器——视交叉上核（SCN）内组织退化的副产品。然而，迄今为止，人们对从老年人或尸检时被诊断为阿尔茨海默病的个体的大脑中获得的 SCN 进行了研究，发现其仅存在有限的萎缩。我们回顾了这些文献，以及一篇关于胎儿供体 SCN 移植的补充文献，该文献证实，许多昼夜节律计时功能可以通过 SCN 的基本（结构受限）表现来维持。这些数据表明，SCN 是一个具有弹性的大脑区域，不能直接（或单独）归咎于衰老过程中以及阿尔茨海默病早期和晚期进展中经常观察到的昼夜节律紊乱的行为表现。我们通过提出可能弥合这一概念鸿沟的未来研究方向来完成综述，并简要讨论了其对改善成年后期健康结果的影响。
