Along these lines, BDNF levels in humans have been linked to a wide variety of brain diseases, among which neuropsychiatric (Nakazato et al. 2003; Binder and Scharfman 2004; Hashimoto et al. 2004, 2006; Gratacos et al. 2007; Machhado-Vieira et al. 2007; Ikeda et al. 2008) and neurodegenerative diseases (Azoulay et al. 2005;Yasutake et al. 2006). Here, BDNF is linked to neurodegenerative disease.