Remarkably, this decrease was not detected in APP/PS1tg x p75NTR KO mice (p75NTR KO vs. APP/PS1tg x p75NTR KO: p = 0.62; APP/PS1tg vs. APP/PS1tg x p75NTR KO: p < 0.05), which indicates a crucial role of p75NTR during AD on the number of dendritic spines. Here, APP is linked to Alzheimer disease.