The history of Alzheimers Disease Alzheimer's Drug Donanemab Helps Most When Taken Early in Disease Scientific American Dihexa (also known as PNB 0408) is an experimental small molecule derived from angiotensin IV. It was engineered to cross the bloodbrain barrier and has shown synaptogenic effects in preclinical models. The often quoted Brain peptides in Alzheimer's disease pathophysiology and therapeutic advances Cell and Tissue Research Springer Nature Link