Finally, genetic association studies showed that some OTR gene polymorphisms might be related to increased risk of developing traumatic experiences and psychiatric disorders, such as PTSD, anxiety, and depression (Cochran et al., 2013; Lucas-Thompson and Holman, 2013; McQuaid et al., 2013; Tollenaar et al., 2017), while other OTR gene polymorphisms might have a protective function (Cicchetti and Rogosch, 2012). Here, OXTR is linked to major depressive disorder.