Imaging amyloid pathology in the living brain

Progressive deposition of amyloid plaques in the brain, which begins before the appearance of cognitive decline, is an initiating event in the pathogenesis of Alzheimer's disease. Therefore, noninvasive detection of amyloid pathology is important for presymptomatic diagnosis and preventive therapy for Alzheimer's disease. Recent research advances have enabled the in vivo imaging of amyloid pathology in humans using nuclear medicine technology. Several amyloid-binding agents have been developed and evaluated by positron emission tomography (PET) and single photon emission computed tomography (SPECT) for their use as contrast agents. Available clinical evidence indicates that amyloid imaging enables the early diagnosis of Alzheimer's disease with high accuracy and suggests its usefulness for the prediction of progression to Alzheimer's disease in subjects with mild cognitive impairment and probably also in cognitively normal individuals. Another application of this technology is as a surrogate marker for monitoring brain amyloid. In this review, we describe recent progress in the development of amyloid imaging technology and human clinical trials.