Podcast episode 75 (in German)
Dihexa – when the foundation is retracted
September 13, 2026
An episode that takes back an earlier episode. The paper that had shown Dihexa’s mechanism of action was retracted, and the figure used to advertise the substance everywhere comes not from a study but from a press release.
What it is about
Dihexa is a small synthetic molecule from Washington State University, designed to make nerve cells form new contacts via the growth factor HGF and its receptor c-Met. This episode tells what is left of the story: in April 2025, a scientific journal retracted three papers by the group, including precisely the one that had demonstrated the mechanism — the reason was manipulated figures. In parallel, the idea behind it was tested with another agent from the same school of thought in a large Alzheimer’s study and clearly missed its endpoint. The episode makes a clean distinction: the signaling pathway is real, the evidence for this molecule is not, and in humans there is still nothing on Dihexa to this day.
Key points
- In April 2025, the journal in question retracted 3 papers by the research group, including the 2014 study that had shown the mechanism of action in the first place.
- A university investigation concluded that a co-author had altered figures in her doctoral thesis and in at least 4 publications.
- The advertising figure — 10 million times more potent than BDNF, that is 7 orders of magnitude — comes from a press release from October 2012 in which the two substances were never compared.
- The Alzheimer’s study LIFT-AD enrolled 554 patients, 287 of them in the main analysis, over 26 weeks; the primary endpoint came in at a p-value of 0.7.
- The threshold is considered to be 0.05, and 0.7 means: nothing could be seen between the agent and placebo. 2 smaller studies before it were also negative.
- The introductory paper on Dihexa has not been retracted, but has been under a formal expression of concern since 2021 — without a decision for 5 years.
- In humans there are 0 studies: none ongoing, none terminated, no case report, not a single entry in a trial registry.
Where the data stop
Where the data stop is quickly said here: in humans, nothing exists on Dihexa. What remains are 4 independent groups with animal and cell studies that contradict each other — one found better cognition in an Alzheimer’s mouse model, another saw no protection in a Huntington’s model in 40 rats, plus 2 stem cell papers that use the substance in cell culture as an HGF substitute. Whether it actually binds to HGF has never been measured independently by anyone.
Added to this is a safety profile that consists not of warnings but of blanks: c-Met is an established cancer gene against which drugs are being developed — here it is supposed to be switched on. In rat experiments the half-life is 13 days, so with repeated administration the substance accumulates, and there are no long-term data. Dihexa is not approved as a medicine anywhere; for athletes it falls under the non-approved substances prohibited at all times.
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Published on September 13, 2026.
The topic in the database
- A synaptogenesis peptide: said to drive the formation of new nerve connections – the advertised potency comes from a press release.Dihexa
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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-10-09.