Educational content only — this is not medical advice. Nothing here is a recommendation to buy, obtain, or use P21. Talk to a licensed clinician before making health decisions.
What it is
P21 is a synthetic 4-amino-acid peptide derived from a CNTF receptor-activation domain. It is designed to mimic the neurotrophic effects of CNTF without the side effects of the full protein. In animal models it increases neurogenesis and improves memory.
What the evidence shows
In transgenic Alzheimer's mouse models, P21 has been reported to improve spatial memory, increase dentate gyrus neurogenesis, and reduce neuroinflammation. These are promising preclinical findings, but no human trials have been published.
Risks & unknowns
Human safety and pharmacokinetics are unknown. As with other neurotrophic peptides, theoretical concerns include uncontrolled cell growth and immune responses.
Legal / regulatory status
P21 is not FDA-approved and is not legal to market for human use.