P21 (P021) is a peptide that is commonly used to increase levels of brain-derived neurotrophic factor (BDNF), thereby promoting neuronal growth and neuroprotection, especially in brain regions associated with Alzheimer's disease. In animal models, P21 has been shown to enhance cognitive function and inhibit the formation of amyloid plaques and Tau proteins, which are the main features of Alzheimer's disease.
