Dihexa Peptide for Cognition & Treating Neurodegeneration Small molecule activation of the neurotrophin hepatocyte growth factor to treat Alzheimer disease 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 Dihexa Peptide: Complete Guide to Synaptogenesis (2026) D I H E X A is having a moment right now and I get why. When something gets labeled as brain repair or synapse growth, it spreads FAST especially in communities