What is Dihexa?
Dihexa is a small synthetic molecule built from a modified angiotensin IV fragment. Angiotensin IV is a breakdown product of angiotensin II, a hormone best known for its role in blood pressure. Researchers had noticed that angiotensin IV seemed to affect memory in animals, but it breaks down quickly in the body. Dihexa was designed to be more stable, and in rat studies it was reported to reach the brain when given by mouth.
The compound came out of research at Washington State University aimed at Alzheimer's disease and other conditions that involve the loss of connections between nerve cells. Most of the published work on Dihexa comes from that one research group. It remains an experimental compound, and its effects in people have not been studied in published trials.
How does Dihexa work?
According to the researchers who developed it, Dihexa binds to hepatocyte growth factor (HGF) and strengthens its signaling through the c-Met receptor. In the brain, the HGF/c-Met system is involved in the growth of nerve cells and the formation of synapses, the connections between them. In cell culture, the developers reported that Dihexa promoted the growth of dendritic spines, the small structures where synapses form, at extremely low concentrations compared with BDNF. That comparison is a lab measure of potency, not evidence of a stronger effect in a living brain.
What has research looked at?
- Memory in rats
- In rat studies, Dihexa improved performance in a water maze memory task, both in animals with memory problems caused by the drug scopolamine and in aged rats.
- Synapse formation
- In nerve cell cultures and rat brain tissue, researchers reported more dendritic spines and new synapses. Blocking the HGF/c-Met system blocked these effects, which supports the proposed mechanism.
- Neurodegeneration models
- The same research group has explored Dihexa and related compounds in animal models of neurodegenerative disease. These remain early animal findings.
- A related drug in people
- Fosgonimeton, a different compound that came from the same line of HGF/c-Met research, was tested in people with Alzheimer's disease. In mid-stage clinical trials, it did not meet its main goals.
The evidence for Dihexa itself is limited to cell and animal studies, mostly from a single group. No published clinical trials have tested it in people, so its effects and safety in humans are unknown. Memory gains seen in rats often do not carry over to people.
Is Dihexa a peptide?
Dihexa is often called a peptide, but it is better described as a peptide-like molecule. Its core is just two standard amino acids, tyrosine and isoleucine, with chemical groups added at each end to protect it from breakdown. This design is why it was reported to work by mouth in rats, unlike most peptides, which are digested in the gut. It differs from brain-related compounds such as Semax and Cerebrolysin in structure and in how much human research exists.
Side effects and cautions
Because Dihexa has not been studied in published human trials, its side effects in people are not known. Informal reports mention headache, irritability and mood changes, but these are not reliable data. The bigger concern is theoretical. The HGF/c-Met system drives cell growth, and overactive c-Met signaling is involved in the growth and spread of many cancers. Researchers have raised the question of whether long-term activation could carry cancer risk. Anyone thinking about experimental compounds should talk to a qualified clinician.
- Cancer history
- The c-Met link is a particular concern for anyone with a current or past cancer.
- Unknown long-term effects
- The effects of strengthening a growth pathway over months or years have not been studied.
- Pregnancy and breastfeeding
- There are no safety data, and growth signaling is especially important during development.
Further reading
This page summarizes the research in plain words. To read the studies yourself:
- Published studies on Dihexa PubMed, US National Library of Medicine
