[Contribution of molecular imaging research to innovative drug development]

Nowadays, abnormally aggregated proteins which have pivotal role in the pathology of neurodegenerative dementia, such as amyloid β, hyperphosphorylated tau, α-synuclein and so on, have been become major targets of molecular neuroimaging as well as disease modifying treatment for dementia. All the amyloid-targeted agents have so far ended with disappointing results and have failed to bring about any delay in the disease progression; however, it has been shown that amyloid imaging demonstrates strong concordant with histopathology for brain amyloid β, and is useful for therapeutic drug monitoring as well as an appropriate recruitment of participants to clinical trial monitoring. Furthermore, a number of novel and practical PET ligands for tau imaging have also been developed recently. Some basic and clinical evidences suggest that tau-targeting drug might bring about delay in the disease progression for tau-mediated neurodegenerative dementia, and therefore it is expected that tau imaging would promote establishing disease modifying treatments for dementia. The aim of this article is to present the current situation of molecular imaging research in dementia, and to further discuss the application possibility of the molecular imaging to innovative drug development.