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Cognitive

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CNTF mimetic (cognitive)

P21

Also known as: P021, Cinaciguat (no — different compound), Neurotrophic peptidomimetic compound 21

Animal-only compound designed to mimic a brain growth factor. Strong rodent data on new neuron formation and cognitive recovery in disease models; zero published human evidence.

Reviewed 2026-05-05

What it does

P21 is a small synthetic compound designed to mimic a fragment of a natural brain growth factor (ciliary neurotrophic factor) while remaining small enough to cross the blood–brain barrier. Rodent studies in models of Alzheimer's disease, traumatic brain injury, and neonatal brain injury have shown enhanced new-neuron formation in the hippocampus, restored cognitive performance, and reduced disease-related brain pathology. None of this has translated to a published human trial. Community marketing for nootropic stacking, particularly via vendors that pair it with dihexa, runs ahead of the evidence by an extreme margin.

Used for

Dose

Starting
100 mcg · once daily (varies wildly)
Common
550 mcg · once daily (varies wildly)
Upper
1,000 mcg · once daily (varies wildly)
When
MorningCognitive-enhancement claims center on neurogenesis + BDNF. No human chronopharmacology, but the alertness signal favors morning to avoid sleep interference.
Site
oral, sublingual, or subcutaneous (community use, no human dose-finding study)

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⚠ Caution

  • Any active malignancy (CNTF / leptin / JAK-STAT signaling overlaps with proliferation pathways; safety unknown)
  • Pregnancy and breastfeeding
  • Pediatric use (any animal-only compound is inappropriate for children outside formal trials)
  • Use during active immunotherapy or chemotherapy (interaction with disease biology unknown)
  • Known hypersensitivity

Your stack

Track this peptide in your protocol — dose, schedule, vials on hand, refill projection. Stays in your browser; no account needed.

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Reconstitution & storage

Vendor preparations vary; powder forms reconstituted with bacteriostatic water or sterile saline depending on route. Oral and sublingual community use does not require reconstitution.

Storage. Vendor-dependent. Powder forms typically refrigerated; oral preparations at room temperature, dry, protected from light.

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Monitoring & questions

Reported side effects
  • Unknown in humans — no published human safety data
  • Anecdotal community reports: headache, irritability, sleep disturbance, anxiety; uncontrolled and unverified
  • Theoretical: any neurogenic compound has uncharacterized long-term effects on adult brain plasticity and seizure threshold
Biomarkers Juno tracks

Reference

How it works

Mimics a neurogenic fragment of CNTF (ciliary neurotrophic factor) but is small enough to cross the blood–brain barrier. Activates leptin/JAK/STAT and BDNF-related signaling pathways implicated in adult hippocampal neurogenesis, enhances neurite outgrowth, and reduces tau hyperphosphorylation in animal AD models. The exact receptor target in humans is incompletely characterized.

Juno's take

The rodent data is genuinely interesting — neurogenesis effects with reduced disease pathology across multiple injury models. But every human-applicable claim is extrapolation from animal disease work. There is no published human trial at any phase. The 'nootropic for healthy adults' framing is doubly removed: the rodent studies were in cognitively-impaired animals, not normal ones, and the human translation step has never been taken.

EvidenceTier 4 — Anecdotal

Tiers are per indication. The same molecule can be Tier 1 for one use and Tier 4 for another — the tier reflects published literature, not community framing.

Neurogenesis / cognitive enhancement (animal models)

Tier 4high confidence

Multiple rodent studies (Bolognin/Iqbal 2014, Khatoon 2015) demonstrate hippocampal neurogenesis and cognitive recovery in AD and TBI models. Effect sizes are striking but confined to animals; no published human study has reported results.

Bolognin S et al. 2014

Alzheimer's disease

Tier 4high confidence

Patent literature and preclinical work position P21 as an AD candidate. No human trial has reached publication. Community use as an AD intervention is unsupported by clinical evidence.

No primary citations are anchored to this indication — the tier reflects the absence of usable literature, not a missing reference.

Cognitive enhancement / nootropic in healthy adults

Tier 4high confidence

Mechanistic extrapolation. There is no human evidence of cognitive benefit in healthy adults — the rodent studies were all in disease models, not normal animals.

No primary citations are anchored to this indication — the tier reflects the absence of usable literature, not a missing reference.

Citations (1)
  1. [1]
    An experimental rat model of sporadic Alzheimer's disease and rescue of cognitive impairment with a neurotrophic peptide
    Bolognin S, Blanchard J, Wang X, et al. (Iqbal K, group) · Acta Neuropathologica · 2014 · PMID 24710115
    Anchor preclinical demonstration of P21's procognitive effects in a rat AD model. Tier 4 because no human translation exists.
    View source