OPRM1 and Borderline personality disorder: Indeed, MOR upregulation (i.e., increased receptor density) has been linked to extreme dysphoria as seen in many cases of psychopathology, and irritability as seen in Major Depression (214), Post-traumatic Stress Disorder (220), Borderline Personality Disorder (BPD) (187, 221–224) and Attachment Disorders (188, 225).