The most definitive classification systems for dementia are based on the underlying pathology which, in turn, is categorized largely according to the observed accumulation of abnormal protein aggregates in neurons and glia. These aggregates perturb molecular processes, cellular functions and, ultimately, cell survival, with ensuing disruption of large-scale neural networks subserving cognitive, behavioural and sensorimotor functions. The functional domains affected and the evolution of deficits in these domains over time serve as footprints that the clinician can trace back with various levels of certainty to the underlying neuropathology. The process of phenotyping and syndromic classification has substantially improved over decades of careful clinicopathological correlation, and through the discovery of in vivo biomarkers of disease. Here, we present an overview of the salient features of the most common dementia subtypes — Alzheimer disease, vascular dementia, frontotemporal dementia and related syndromes, Lewy body dementias, and prion diseases — with an emphasis on neuropathology, relevant epidemiology, risk factors, and signature signs and symptoms.

痴呆症最明确的分类系统是基于潜在的病理学，而病理学则主要根据观察到的神经元和神经胶质中异常蛋白质聚集物的积累进行分类。这些聚集物扰乱了分子过程，细胞功能，最终破坏了细胞存活，随之而来的是破坏了大规模的神经网络，从而破坏了认知，行为和感觉运动功能。受影响的功能结构域以及这些结构域中的缺陷随着时间的推移而发展，成为临床医生可以以各种确定性水平追溯到潜在神经病理学的足迹。经过数十年的仔细临床病理学关联以及通过体内发现，表型和症状分类的过程已得到实质性改善疾病的生物标志物。在这里，我们概述了最常见的痴呆亚型的主要特征-阿尔茨海默病，血管性痴呆，额颞痴呆及相关综合征，路易体痴呆和病毒疾病-着重于神经病理学，相关流行病学，危险因素和签名迹象和症状。