Alzheimer's disease, the most common cause of dementia, is characterized by two 
major pathological hallmarks: amyloid plaques and neurofibrillary tangles. Based 
on these two indicators, an amyloid cascade hypothesis was proposed, and 
accordingly, most current therapeutic approaches are now focused on the removal 
of β-amyloid peptides (Aβ from the brain. Additionally, strategies for blocking 
tau hyperphosphorylation and aggregation have been suggested, including the 
development of drugs that can block the formation of tangles. However, there are 
no true disease-modifying drugs in the current market, though many drugs based 
on theories other than Aβ and tau pathology are under development. The purpose 
of this review was to provide information on the current development of AD drugs 
and to discuss the issues related to drug development.