Importantly, the observed age-dependent decline in the BDNF+/−-mice seems to appear later and to a weaker extent than in the APP/PS1- or APP/PS1-BDNF+/−-mice, suggesting that the observed accelerated onset of impaired TWAA learning in the young triple transgenic animals is rather due to an accelerated AD-like pathology in combination with chronically reduced BDNF protein levels than simply due to the chronic BDNF reduction alone. This evidence concerns the gene APP and Alzheimer disease.