阿尔茨海默病（AD）是痴呆最常见的原因。目前关于其潜在病理学的主流理论认为淀粉样物质积聚导致了tau蛋白的聚集和神经退行性变。然而，目前的抗淀粉样物质和抗tau蛋白的治疗方法仅显示出不一致的临床疗效。对于痴呆的放射学评估有三个相关要点很重要。首先，除了各种痴呆症状（包括AD、额颞叶痴呆和帕金森痴呆）之外，AD的临床变体和成像亚型包括典型AD和非典型AD。其次，非典型AD在放射学和临床表现上与其他疾病有重叠之处。第三，诊断过程应考虑到神经退行性疾病中常见的并发脑血管病变，特别是在老年人中。在认知减退出现之前，神经元丢失常常已经存在。因此，为了有效的新治疗方法，在临床症状出现之前进行早期诊断是减缓或停止随后神经元丢失的重要环节，需要进行分子成像或血浆生物标志物。神经影像学，特别是MRI，提供了用于神经退行性和脑血管疾病的多个成像参数。随着AD新治疗方法的出现，越来越重要的是识别AD的变异和模仿AD的其他疾病。描述神经退行性和脑血管疾病标记物的个体组成，考虑到重叠和混合疾病是必要的，以更好地理解AD并开发高效的个体化治疗方法。© RSNA，2023同期专题还有Pasquini等人的文献回顾 "Functional MRI in Neuro-Oncology: State of the Art and Future Directions"。

Alzheimer disease (AD) is the most common cause of dementia. The prevailing theory of the underlying pathology assumes amyloid accumulation followed by tau protein aggregation and neurodegeneration. However, the current antiamyloid and antitau treatments show only variable clinical efficacy. Three relevant points are important for the radiologic assessment of dementia. First, besides various dementing disorders (including AD, frontotemporal dementia, and dementia with Lewy bodies), clinical variants and imaging subtypes of AD include both typical and atypical AD. Second, atypical AD has overlapping radiologic and clinical findings with other disorders. Third, the diagnostic process should consider mixed pathologies in neurodegeneration, especially concurrent cerebrovascular disease, which is frequent in older age. Neuronal loss is often present at, or even before, the onset of cognitive decline. Thus, for effective emerging treatments, early diagnosis before the onset of clinical symptoms is essential to slow down or stop subsequent neuronal loss, requiring molecular imaging or plasma biomarkers. Neuroimaging, particularly MRI, provides multiple imaging parameters for neurodegenerative and cerebrovascular disease. With emerging treatments for AD, it is increasingly important to recognize AD variants and other disorders that mimic AD. Describing the individual composition of neurodegenerative and cerebrovascular disease markers while considering overlapping and mixed diseases is necessary to better understand AD and develop efficient individualized therapies.© RSNA, 2023 See also the review "Functional MRI in Neuro-Oncology: State of the Art and Future Directions" by Pasquini et al in this issue.