BDNF and early-onset autosomal dominant Alzheimer disease: It has been well demonstrated that CRTC1, BDNF and neurogenesis play critical roles in not only depression but also many other neurological disorders, such as Alzheimer's disease, Parkinson's disease, stroke and epilepsy (Liu et al., 2010; Mu and Gage, 2011; Saura, 2012; Yu et al., 2013; Wang et al., 2016; Koh and Park, 2017; Parra-Damas et al., 2017; Tanila, 2017; Lim et al., 2018; Mohammadi et al., 2018).