On a clinical level, PTSD is a frequent consequence of CAN in patients with SUD. Among patients treated for SUD, 26–52% have a lifetime diagnosis of PTSD and 15–41% currently meet criteria for the disorder (Schäfer & Najavits, 2007). In European studies, the rate of current PTSD is slightly lower, but still substantial (e.g. 15–36%; Driessen et al., 2008). However, PTSD is only one of the most obvious consequences of CAN and many SUD patients with a history of CAN suffer from more complex psychological consequences. They typically include pervasive disturbances in ER, a diminished and defeated sense of self, and difficulties in interpersonal relationships (Hien, Cohen, & Campbell, 2005). Such complex symptom presentations can dominate the clinical picture, or they can exist in addition to PTSD, which led the International Classification of Diseases (ICD) task force on stress-related disorders to propose a new diagnosis of ‘Complex PTSD’ for ICD-11 (Maercker et al., 2013).