Department of Neurology, University of California, Irvine, CA, USA.
Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA.
J Alzheimers Dis. 2021;82(1):129-147. doi: 10.3233/JAD-201578.
The oldest-old, those 85 years and older, are the fastest growing segment of the population and present with the highest prevalence of dementia. Given the importance of neuroimaging measures to understand aging and dementia, the objective of this study was to review neuroimaging studies performed in oldest-old participants. We used PubMed, Google Scholar, and Web of Science search engines to identify in vivo CT, MRI, and PET neuroimaging studies either performed in the oldest-old or that addressed the oldest-old as a distinct group in analyses. We identified 60 studies and summarized the main group characteristics and findings. Generally, oldest-old participants presented with greater atrophy compared to younger old participants, with most studies reporting a relatively stable constant decline in brain volumes over time. Oldest-old participants with greater global atrophy and atrophy in key brain structures such as the medial temporal lobe were more likely to have dementia or cognitive impairment. The oldest-old presented with a high burden of white matter lesions, which were associated with various lifestyle factors and some cognitive measures. Amyloid burden as assessed by PET, while high in the oldest-old compared to younger age groups, was still predictive of transition from normal to impaired cognition, especially when other adverse neuroimaging measures (atrophy and white matter lesions) were also present. While this review highlights past neuroimaging research in the oldest-old, it also highlights the dearth of studies in this important population. It is imperative to perform more neuroimaging studies in the oldest-old to better understand aging and dementia.
最年长的老年人，即 85 岁及以上的老年人，是人口中增长最快的群体，也是痴呆症患病率最高的群体。鉴于神经影像学测量对了解衰老和痴呆症的重要性，本研究的目的是回顾在最年长的老年人参与者中进行的神经影像学研究。我们使用 PubMed、Google Scholar 和 Web of Science 搜索引擎，确定了在体内 CT、MRI 和 PET 神经影像学研究中，要么在最年长的老年人中进行，要么在分析中明确将最年长的老年人作为一个不同的群体。我们确定了 60 项研究，并总结了主要的群体特征和发现。一般来说，与年轻的老年人参与者相比，最年长的老年人参与者表现出更大的萎缩，大多数研究报告说，随着时间的推移，大脑体积的相对稳定的持续下降。大脑整体萎缩和内侧颞叶等关键大脑结构萎缩较大的最年长的老年人更有可能患有痴呆症或认知障碍。最年长的老年人有很高的白质病变负担，这与各种生活方式因素和一些认知测量有关。通过 PET 评估的淀粉样蛋白负担虽然在最年长的老年人中比在年轻年龄组中更高，但仍可预测从正常认知到认知障碍的转变，尤其是当存在其他不良神经影像学测量（萎缩和白质病变）时。虽然本综述强调了过去在最年长的老年人中进行的神经影像学研究，但也强调了在这个重要人群中缺乏研究。在最年长的老年人中进行更多的神经影像学研究至关重要，以更好地了解衰老和痴呆症。
