Last updated: March 2026
NSI-189 is a neurogenic small molecule from Neuralstem Inc. that promotes hippocampal neural stem cell proliferation. It reached Phase 2 trials for major depressive disorder. The primary endpoint was missed, but ~2.4% hippocampal volume increases and cognitive improvements were observed — making it a uniquely interesting compound in the neurogenesis space.
NSI-189 is a benzylpiperazine aminopyridine that stimulates the proliferation and neuronal differentiation of hippocampal neural progenitor cells — offering a unique neurogenic approach to depression and cognitive decline distinct from monoamine-based therapies.
NSI-189 directly stimulates hippocampal neural stem cell proliferation — the same process by which exercise and antidepressants are hypothesized to work, but through a direct neurogenic mechanism. Adult hippocampal neurogenesis is linked to mood regulation, memory formation, and stress resilience.
In Phase 2 MRI imaging, subjects taking NSI-189 for 12 weeks showed ~2.4% hippocampal volume increase vs. placebo. Hippocampal volume loss is a hallmark of chronic depression and stress. This structural change is measurable and biologically meaningful, even if the primary endpoint was not met.
NSI-189's neurogenic activity is mechanistically distinct from SSRIs, SNRIs, and other antidepressants. It does not appear to act primarily via serotonin, norepinephrine, or dopamine reuptake. The exact molecular target(s) driving its neurogenic effect remain under investigation.
Secondary outcome data from the Phase 2 trial showed subjective cognitive improvements including improvements in memory and executive function measures. Hippocampal neurogenesis is closely tied to spatial memory and pattern separation — the types of cognition most affected by hippocampal volume loss in depression.
Key data from Fava et al. (2016) Phase 2 RCT and associated neuroimaging studies. N=220 MDD patients, 40mg/day for 12 weeks.
Tools for tracking neurogenesis-adjacent interventions.
Dosing schedules, interaction warnings, and cycle protocols for 50+ compounds — all in one place.
This page is for educational and informational purposes only. NSI-189 is a research compound that failed its Phase 2 primary endpoint and is not approved for any indication. It is not available as a pharmaceutical drug. This is not medical advice. Consult a qualified physician before using any research compound, especially those affecting brain neurochemistry.