Amyloid-β as a biomarker for Alzheimer's disease: quantification methods in body fluids

Alzheimer's disease (AD) is the most common neurodegenerative disorder, characterized by neuronal impairment leading to dramatic changes in brain. Amyloid-β peptides and tau protein are the most promising biomarkers for AD. Cerebrospinal fluid and plasma are used to determine the concentration of these species. Since the pathological processes of AD start decades before the first symptoms, biomarkers may provide the possibility of early disease detection. The application of rapidly emerging technology, such as mass spectrometry, has opened new avenues to accelerate biomarker discovery, both for diagnostic as well as for prognostic purposes. This review summarizes AD biomarker studies with focus on amyloid-β peptides in biological fluids and their quantification with immunoassays as well as the latest mass spectrometry-based methods.