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 Hepatocyte Growth Factor MET Activator Rescues Working Memory Deficits After Repeated Mild Traumatic Brain Injury Adult Hippocampal Neurogenesis in the Human Brain: Updates, Challenges, and Perspectives Sophie Simard, Natalie Matosin, Naguib Mechawar, 2025 Current understanding of adult neurogenesis in the mammalian brain: how does adult neurogenesis decrease with age? Inflammation and Regeneration Springer Nature Link