Current status of PET tracers for the early diagnosis of Alzheimer's disease

Positron emission tomography (PET) is a non-invasive imaging technology that can reveal molecular alterations in the brains of Alzheimer's disease (AD) patients with high sensitivity and specificity, which is crucial for clinical diagnosis, disease staging, and monitoring potential therapeutic approaches. Several biomarkers contribute to the clinical diagnosis of AD, and according to the evolving ATX(N) framework, these biomarkers can be classified into the amyloid-β (A) pathway, Tau-mediated pathophysiology (T), neurodegeneration (N), and other related molecular and cellular network changes in the AD continuum (X), such as neuroinflammation, synaptic dysfunction, and neurochemical deficits. This review provides an overview of PET tracers reported for several typical and classical targets in early AD diagnosis and compares tracers targeting the same biomarkers. We believe this review will support and facilitate progress in early AD diagnosis and further propose the future potential of both PET tracers and targets.