The oxytocin signaling pathway is linked to social behaviors, as well as several psychiatric disorders (e.g., depression) (Feldman et al., 2016) Interestingly, a DMR was recently identified in the oxytocin gene (OXT), which was hypomethylated in AD brain (Lardenoije et al., 2019; Watson et al., 2016) and hypermethylated in the blood in individuals who subsequently converted to AD (Lardenoije et al., 2019). Here, OXT is linked to major depressive disorder.