P21
Ciliary neurotrophic factor-derived peptidergic compound
A CNTF-derived fragment studied for neurogenesis and BDNF elevation in models of Alzheimer's disease.
Last reviewed · 1 references
How it works
P21 is an 11-amino-acid fragment derived from the active region of ciliary neurotrophic factor. In rodent models it increases hippocampal neurogenesis, elevates BDNF, and reduces tau hyperphosphorylation — the combination is why it draws attention in the Alzheimer's literature.
Animal studies only. Findings come from rodent or in-vitro models. Animal results frequently fail to replicate in people.
What the research reports
- Increased hippocampal neurogenesis in mice
- Elevated BDNF and reduced tau hyperphosphorylation
- Improved cognition in transgenic Alzheimer's models
What it has not been shown to do
- No human studies
- No human safety or dosing data
Dosing reference
No human reference dose exists.
Calculate my dose for P21- Routes studied
- Intranasal, Subcutaneous
- Half-life
- Not characterised in humans
- Cycle length in the literature
- Not established
Working out a draw volume from a vial? Use the free reconstitution calculator.
Side effects and contraindications
Reported side effects
- Unknown in humans
Do not use if
- Pregnancy and breastfeeding
- No human safety data of any kind
The practice that shares the mechanism
Neurogenesis produces new cells; survival of those cells is activity-dependent. In animal work, new hippocampal neurons that are not recruited by learning die off. Practice is not optional to the mechanism — it is part of it.
What amplifies it
- Learning something genuinely difficult during the window
- Sleep, which governs whether new circuits are retained
Mechanism hubs
Common questions
- It circulates as a research chemical. There is no pharmaceutical supply, no approved use, and no human dosing evidence to reference.
Sources & evidence notes
Findings come from rodent or in-vitro models. Animal results frequently fail to replicate in people.
Confidence score 3/100
Preliminary
Mechanism only. Nothing here establishes that a person would feel anything.
- 1.
Journal of Alzheimer's Disease, 2014 · Source (opens in a new tab)
In vitroLimited gradeCells or tissue in a dish. Tells you about mechanism, not about outcomes.