LEP and Alzheimer disease: In patients, abnormally low levels of plasmatic leptin were observed (Holden et al. 2009), and in an AD animal model a reduced sensitivity of hypothalamus to leptin itself was found (Ishii et al. 2014); the latter phenomenon may result in the dysregulation of appetite, in particular in low calories intake despite the reduction of body weight (Ishii and Iadecola 2015).