Rapidly progressive dementias (RPDs) are a group of heterogeneous disorders that include immune-mediated, infectious and metabolic encephalopathies, as well as prion diseases and atypically rapid presentations of more common neurodegenerative diseases. Some of these conditions are treatable, and some must be diagnosed promptly because of their potential infectivity. Prion disease is considered to be the prototypical RPD, but over the past two decades, epidemiological reports and the identification of various encephalitis-mediating antibodies have led to a growing recognition of other encephalopathies as potential causes of rapid cognitive decline. Knowledge of RPD aetiologies, syndromes and diagnostic work-up protocols will help clinicians to establish an early, accurate diagnosis, thereby reducing morbidity and mortality, especially in immune-mediated and other potentially reversible dementias. In this Review, we define the syndrome of RPD and shed light on its different aetiologies and on secondary factors that might contribute to rapid cognitive decline. We describe an extended diagnostic procedure in the context of important differential diagnoses, discuss the utility of biomarkers and summarize potential treatment options. In addition, we discuss treatment options such as high-dose steroid therapy in the context of therapy and diagnosis in clinically ambiguous cases.

快速进行性痴呆 (RPD) 是一组异质性疾病，包括免疫介导的感染性和代谢性脑病，以及朊病毒病和更常见的神经退行性疾病的非典型快速表现。其中一些病症是可以治疗的，而另一些则由于其潜在的传染性而必须及时诊断。朊病毒病被认为是典型的 RPD，但在过去的二十年中，流行病学报告和各种脑炎介导抗体的鉴定使人们越来越认识到其他脑病是认知能力快速下降的潜在原因。了解 RPD 病因、综合征和诊断检查方案将有助于临床医生建立早期、准确的诊断，从而降低发病率和死亡率，特别是在免疫介导的和其他可能可逆的痴呆症中。在这篇综述中，我们定义了 RPD 综合征，并阐明了其不同的病因以及可能导致认知能力快速下降的次要因素。我们描述了重要鉴别诊断背景下的扩展诊断程序，讨论了生物标志物的效用并总结了潜在的治疗方案。此外，我们还讨论了治疗方案，例如在临床上模棱两可的病例的治疗和诊断背景下的大剂量类固醇治疗。我们描述了重要鉴别诊断背景下的扩展诊断程序，讨论了生物标志物的效用并总结了潜在的治疗方案。此外，我们还讨论了治疗方案，例如在临床上模棱两可的病例的治疗和诊断背景下的大剂量类固醇治疗。我们描述了重要鉴别诊断背景下的扩展诊断程序，讨论了生物标志物的效用并总结了潜在的治疗方案。此外，我们还讨论了治疗方案，例如在临床上模棱两可的病例的治疗和诊断背景下的大剂量类固醇治疗。