Published online by Cambridge University Press: 07 November 2014
Alzheimer's disease (AD) is a progressive disorder in which neurodegeneration begins decades before clinical symptoms appear. Detecting AD during this preclinical phase presents both the enormous challenge of identifying at-risk patients prior to symptom onset and the potential reward of treating patients early enough to prevent or slow disease progression. Given that a 5-year delay in the onset of the clinical manifestations of AD could result in almost a 50% reduction in disease prevalence, early detection of AD is a major focus of clinical research. Several objective, measurable indicators of preclinical and clinical characteristics of AD are currently available or in development. These biomarkers are promising because they promote identification of individuals at risk for AD onset and disease progression; diagnostic accuracy and treatment during the early stages of AD; and the development of disease-modifying therapies that may potentially slow or prevent disease progression during the preclinical phase of AD.