Some of the studies found that anxiety-like behaviors of BDNF(±) mice is indistinguishable from littermate controls (Chourbaji et al., 2004; Ibarguen-Vargas et al., 2009; Lindholm et al., 2012), whereas others found that these mice are more aggressive and display increased anxiety (Lyons et al., 1999; Chen et al., 2006; Li et al., 2010). This evidence concerns the gene BDNF and Anxiety.