[Full-scale setback and thinking in R&D of Alzheimer's disease drug].

During the past 30 years, Alzheimer's disease (AD) drug R&D aiming at a variety of potential targets has undergone tremendous setback although a large amount of resources have been invested by pharmaceutical companies, governments, academic institutions and venture capitals globally. There is no doubt that uneasy early diagnosis, unsatisfying therapeutic strategies and genetic polymorphism of AD patients bringing variety of responses to the drugs contribute to the failure of AD drug therapy, but the most important reason might be that people have insufficient understanding of the very complex diseases including AD. Continuing to make efforts in the previous way to find AD drugs might not be a good way. Development of systems biomedicine opens an avenue to understand the disease networks and pursue multi-target drugs R&D based on systems pharmacology theory; neural stem cell transplantation, and neurogenesis affected by small molecules might bring new hope for AD therapy; discovery of new biomarkers of AD will help the study of the pathogenesis and diagnosis of the disease and finally the discovery of new types of AD drugs.