Rapidly progressive dementia is a syndrome caused by numerous disease entities. Accurate diagnosis is crucial as substantial proportion of these diseases is highly treatable. Others might implicate specific hygienic problems. Still, differential diagnosis remains challenging because of a huge overlap of clinical presentations. Areas covered: The paper reviews PubMed-listed research articles with a focus on diagnosis and treatment of diseases showing rapid cognitive decline such as inflammatory diseases, rapidly progressive neurodegenerative diseases, toxic-metabolic encephalopathies and prion diseases. The literature was interpreted in the light of experience in clinically differentiating rapid progressing dementia in the framework of Creutzfeldt-Jakob-Disease (CJD) surveillance activities. An overview of relevant differential diagnoses and diagnostic pitfalls as well as therapeutic protocols is presented. Expert commentary: Over the last years, more and more neurologic disorders causing cognitive symptoms, in particular various types of immune-mediated diseases have been discovered. To identify treatable conditions and to enhance knowledge of differential diagnosis and epidemiology, we suggest an extended diagnostic work up in cases with rapidly progressing dementia. Besides standard methods, this should include the search for neoplasia as well as atypical encephalitis. High-dose steroid therapy should be considered in certain clinical situations even when no evidence for inflammation is present.
Keywords: Dementia; differential diagnosis; encephalitis; neurodegenerative diseases; prion diseases; rapidly progressive dementia.