Schaeffer Morgan J, Chan Leona, Barber Philip A
Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada.
Neural Regen Res. 2021 Aug;16(8):1490-1499. doi: 10.4103/1673-5374.303011.
Structural brain changes indicative of dementia occur up to 20 years before the onset of clinical symptoms. Efforts to modify the disease process after the onset of cognitive symptoms have been unsuccessful in recent years. Thus, future trials must begin during the preclinical phases of the disease before symptom onset. Age related cognitive decline is often the result of two coexisting brain pathologies: Alzheimer's disease (amyloid, tau, and neurodegeneration) and vascular disease. This review article highlights some of the common neuroimaging techniques used to visualize the accumulation of neurodegenerative and vascular pathologies during the preclinical stages of dementia such as structural magnetic resonance imaging, positron emission tomography, and white matter hyperintensities. We also describe some emerging neuroimaging techniques such as arterial spin labeling, diffusion tensor imaging, and quantitative susceptibility mapping. Recent literature suggests that structural imaging may be the most sensitive and cost-effective marker to detect cognitive decline, while molecular positron emission tomography is primarily useful for detecting disease specific pathology later in the disease process. Currently, the presence of vascular disease on magnetic resonance imaging provides a potential target for optimizing vascular risk reduction strategies, and the presence of vascular disease may be useful when combined with molecular and metabolic markers of neurodegeneration for identifying the risk of cognitive impairment.
痴呆症相关的脑部结构变化在临床症状出现前20年就已发生。近年来，在认知症状出现后改变疾病进程的努力均未成功。因此，未来的试验必须在疾病的临床前阶段、症状出现之前就开始。与年龄相关的认知衰退通常是两种并存的脑部病变的结果：阿尔茨海默病（淀粉样蛋白、tau蛋白和神经退行性变）和血管疾病。这篇综述文章重点介绍了一些常见的神经成像技术，这些技术用于在痴呆症临床前阶段可视化神经退行性和血管病变的积累，如结构磁共振成像、正电子发射断层扫描和白质高信号。我们还描述了一些新兴的神经成像技术，如动脉自旋标记、扩散张量成像和定量磁化率映射。最近的文献表明，结构成像可能是检测认知衰退最敏感且最具成本效益的标志物，而分子正电子发射断层扫描主要在疾病进程后期用于检测疾病特异性病变。目前，磁共振成像上血管疾病的存在为优化血管风险降低策略提供了一个潜在靶点，并且当与神经退行性变的分子和代谢标志物结合用于识别认知障碍风险时，血管疾病的存在可能会很有用。
