Plasma biomarkers of Alzheimer's disease

Purpose of review The importance of biomarkers of Alzheimer's disease is increasing. The present review aims to offer a general view of plasma biomarkers of Alzheimer's disease and to discuss their relevance and limitations. Recent findings The broad overlap in the plasma amyloid P protein (A beta) levels between patients with Alzheimer's disease and control individuals indicates that the plasma A beta level cannot differentiate cases of sporadic Alzheimer's disease from control cases. Although the significance of A beta for diagnosing Alzheimer's disease is controversial, high plasma concentrations of A beta 40 and low plasma concentrations of A beta 42 indicate an increased risk of dementia. Summary The usefulness of biomarkers in cerebrospinal fluid has been shown by numerous studies; this test is not commonly used, however, and blood biomarkers are therefore preferred. Increasing evidence shows that the plasma A beta concentration may be a premorbid marker for the risk of Alzheimer's disease. It may be used for therapeutic monitoring, diagnosis of A beta deposition in the brain, and also as a surrogate genetic marker to identify novel genetic determinants of Alzheimer's disease. A potential role of plasma A beta concentration as a marker of incipient dementia warrants further investigation.