OXT and Abnormal emotional state: It is of particular interest to study oxytocin in this clinical group because core features of BPD—such as severe emotional dysregulation, interpersonal difficulties, and heightened stress reactivity (American Psychiatric Association 2013; Meehan et al. 2018; Paris 2018), are related to processes modulated by oxytocin, including emotion regulation, stress response, and interpersonal relationships (Carter et al. 2024; Quintana and Guastella 2020; de Jong et al. 2015).