Selegiline is considered by some to be a nootropic, both at clinical and sub-clinical dosages, and has been used off-label to improve cognitive performance. It has been shown to have protective activity against a range of neurotoxins and to increase the production of several brain growth factors, such as nerve growth factor, brain-derived neurotrophic factor, and glial cell-derived neurotrophic factor. It has been demonstrated in numerous animal models to improve learning ability and preserve it during both ischemia and aging.