Dihexa

Dihexa is sold as a memory and cognition peptide. It has no human trials, no human safety data, and the paper describing how it was supposed to work has been retracted. This page covers status and risk only.

What it is

Dihexa is a small modified peptide derived from angiotensin IV, developed at Washington State University. It was designed to be taken orally and to reach the brain, where it was proposed to promote the formation of new synapses.

What the evidence shows

• The published work is rodent studies: maze-based memory tasks and laboratory measures of synapse formation.
• A key paper describing the mechanism, published by the originating group, has been retracted. A second study has drawn criticism. For a compound with so few papers, that is a significant share of the evidence base.
• No human efficacy trial has been completed, and no trial is registered.
• The FDA's own compounding review materials note that the agency has not identified human exposure data for dihexa and lacks important safety information about it.

The specific unknown

Dihexa is described as extraordinarily potent at promoting synapse formation. The pathway it is proposed to act on, HGF and its c-Met receptor, is also involved in cell growth and is implicated in some cancer biology. Whether that matters at the amounts people take is unknown, because the basic toxicology has never been done in any species over a long period.

Dosing

Sources

• Superpower: dihexa evidence, retraction and legal status
• Outliyr: dihexa report and FDA exposure-data note
• Peptide Protocol Wiki: dihexa research gaps