Although hypothalamic CRH neurons are activated in MDD and BD (Belvederi Murri et al., 2016; Menke, 2019), and CRH production is increased in AD and mood disorders (Bao et al., 2012; Guo et al., 2022), no information is available about the possible involvement of PACAP in these disorders. This evidence concerns the gene ADCYAP1 and major depressive disorder.