**5. Conclusions and future perspectives**

AD provides a monumentally challenging drug development landscape. The uncertainty about disease etiology, variability in patient genetics and disease progression, and difficulties in early diagnosis are all but a noncomprehensive list of hurdles to developing effective drugs. Though development of therapeutics to slow or halt AD disease progression, including passive immunotherapeutics, have not yet yielded clinical benefit, the prospect of applying lessons learned in the clinic towards validated targets such as Aβ and tau provides optimism for future success. In addition, our understanding of the mechanisms of other principal contributing factors to disease progression will provide a variety of new targets to explore. Combined with advances in drug technology to increase the availability of biomolecules in the CNS, these clinical and biological advances offer great promise around future success in treating AD.
