Blood and plasma-based proteomic biomarker research in Alzheimer's disease.

Alzheimer's disease (AD) is the most important cause of dementia in the elderly. The molecular alterations preceding this neurodegenerative pathology may take place even 20 years before its clinical appearance. In this context, the discovery of biomarkers in biological fluids enabling an early presymptomatic diagnosis as well as discrimination from other types of dementia is eagerly awaited. In particular, since the traditional markers obtained both from cerebrospinal fluid inspection and neuroimaging approaches have not achieved a broad clinical application, research efforts have been focused on the development and validation of biomarkers in blood. The benefit of searching for blood-based candidate biomarkers is evident due to the easiness and non-invasiveness nature of blood samples collection compared with any other body fluid. As a result, blood may constitute a rich source of disease biomarkers. Interestingly, among the technological platforms used to perform research into the biomarker discovery arena, proteomics has attained more recent consideration. In the present review, we provide a comprehensive assessment of patterns of biomarkers detected in plasma and serum specimens for the diagnosis of AD by employing proteomic approaches. Currently, growing evidence suggests that blood protein signatures are helpful to increase the likelihood of successful diagnosis of AD. Accordingly, this area of research promises to yield exciting results in the next future.