NGF and Alzheimer disease: Stapledon et al. reported a correlation between levels of AD-related genes–including APP, APLP2, β-site amyloid precursor protein cleaving enzyme 1 (BACE1), and nerve growth factor (NGF)—and genes involved in the bone remodeling process—RANK and tartrate-resistant acid phosphatase (TRAP)—as well as the RANK/OPG mRNA ratio in patients admitted with a fracture of the neck of the femur [28].