Hepatocyte Growth Factor MET Activator Rescues Working Memory Deficits After Repeated Mild Traumatic Brain Injury Is Dihexa an approved and safe treatment for cognitive impairment or neurodegenerative diseases such as 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 Stem cell, Granulocyte Colony Stimulating Factor and or Dihexa to promote limb function recovery in a rat sciatic nerve damage repair model: Experimental animal studies ScienceDirect