Is Dihexa safe?

Unknown. There are no human safety studies. The primary concern is that HGF/c-Met signaling promotes cell proliferation and is overactive in many cancers. Whether exogenous HGF enhancement would increase cancer risk in humans is completely untested. This risk alone should give serious pause.

This claim is misleading. The original research found Dihexa was active at picomolar concentrations (very small amounts), while BDNF requires nanomolar concentrations — about a million-fold difference in dose. But potency (how little you need) is not the same as efficacy (how well it works). A lower effective dose does not mean Dihexa produces stronger cognitive effects than BDNF.

Despite being patented in 2012, Dihexa has never entered clinical development. The reasons are unclear but may include concerns about the HGF/c-Met pathway's role in cancer promotion, difficulty securing funding, or insufficient preclinical data to justify the safety risk. This is a significant red flag for a compound marketed as a cognitive enhancer.

In April 2025, Washington State University formally retracted two foundational papers (2012 and 2014) that established the HGF/c-Met mechanism Dihexa's marketing relies on, after an investigation found the lead researcher had falsified images and data. Her PhD was revoked, and her later company (Athira Pharma) paid a $4.07 million federal settlement for failing to disclose the misconduct. This doesn't prove Dihexa has no effect, but it means a meaningful part of the scientific foundation behind how it's claimed to work has been discredited — a serious reason for skepticism beyond the usual "no human trials" caveat.