Dihexa is a peptidomimetic, a small molecule engineered to imitate a peptide, derived from angiotensin IV. It was developed academically at Washington State University and the animal results were striking: it appears to amplify hepatocyte growth factor signalling, which promotes the formation of new connections between neurons, and rodents showed marked cognitive improvements. Those findings are the entire basis for its reputation. It has never been given to a human being in a published trial. No pharmaceutical company has developed it and no first-in-human study is registered. The distance between a rodent maze result and a human cognitive benefit is very large, and in this case it has not been crossed even once.