Finally, different mouse models relevant to schizophrenia show reduced Arc expression, which is instead not evident in mouse models relevant to other psychiatric disorders such as ADHD or bipolar disorders (Matsuo et al., 2009; Takao et al., 2013; Takagi et al., 2015; Managò et al., 2016; Chen et al., 2017; Mereu et al., 2017). This evidence concerns the gene ARC and attention deficit-hyperactivity disorder.