Patients with both PTSD and SUD have a more severe clinical profile than patients with SUD only, especially when trauma occurred early in their lives (see Schäfer and Najavits 2007). They have earlier onset of substance abuse and more years of problematic use, they report more polydrug use, and they have greater severity of current substance use. Patients with SUD and co-occurring PTSD also report worse physical health, lower well-being, and more interpersonal problems. Finally, patients with both disorders are more likely to meet criteria for additional psychiatric disorders, especially major depression and anxiety disorders (Langeland et al. 2004). Large epidemiological surveys also find high rates of other co-occurring disorders among those with PTSD and SUD. In one such study (Mills et al. 2006), almost two-thirds of those with PTSD and SUD had an additional affective disorder, and about half had a comorbid anxiety disorder. Personality disorders were also highly prevalent (62 %). All of these disorders were significantly more frequent in individuals with PTSD and SUD as compared to those with SUD alone or neither disorder. Also, consistent with findings from clinical studies, individuals with PTSD and SUD experienced poorer physical health and greater disability than those with SUD alone.

In addition to worse physical health and more psychiatric comorbidity, patients with complex PTSD present the typical manifestations of this disorder. They suffer from impulsivity and suicidal ideation, self-destructive behaviour, and vulnerability to revictimisation (Hien et al. 2005).

Studies on the relationship between a history of trauma and treatment utilisation in patients with SUD are inconclusive. In a large sample of German outpatients with alcohol dependence, a history of sexual violence was related to higher use of SUD services in female but not in male victims (Schäfer et al. 2009). Victims of both genders were significantly younger at first contact with addiction treatment. Other authors reported that patients with a history of childhood sexual abuse seek less treatment for SUD, at least in institutional contexts (e.g. Peltan and Cellucci 2011). Simpson (2002) reported that with greater severity of childhood sexual abuse, the number of treatments for mental health problems increased, yet the number of substance abuse treatment episodes decreased. She suggested that there may not be a consistent relationship between childhood trauma and SUD treatment utilisation because of the relationship between traumatic experiences and utilisation of other services. While several studies reported a poorer outcome of treatment in patients with a history of childhood trauma (see Schäfer et al. 2009) others could not confirm this relationship. Recently contingency management (Petry et al. 2011) and self-help approaches (Makin-Byrd et al. 2011) have even been reported to have a higher efficacy in SUD patients with abuse histories. With regard to contingency management, one potential mechanism could be that this approach is especially effective in patients with more severe psychopathology, which is often the case in victims of sexual abuse (Petry et al. 2011).

In accordance with the findings among patients with other co-occurring disorders, there seems to be a relatively high lifetime utilisation rate of SUD services in substance abuse patients with PTSD (e.g. Najavits et al. 2004). When they engage in SUD treatment, patients with co-occurring PTSD have a poorer adherence to treatment than patients without the disorder, a shorter duration of abstinence, and worse outcomes across a variety of measures (Schäfer and Najavits 2007). Ouimette et al. (2003) conducted a 5-year follow-up study on one hundred male patients with co-occurring PTSD who attended SUD treatment. Patients who received PTSD treatment in the first 3 months following discharge and those who received treatment for a longer duration in the first year were more likely to be remitted 5 years later. The importance of treating symptoms of PTSD in SUD patients is further supported by studies showing that reductions of PTSD severity during treatment were likely to be associated with substance use improvement whereas substance use symptom reduction had little impact on symptoms of PTSD (e.g. Hien et al. 2010a, b). While the negative influence of comorbid PTSD on treatment outcome is clear, more research is needed on other potential factors. For instance, SUD patients with and without comorbid PTSD are also known to differ on other proximal determinants of treatment response, such as social support and coping strategies.

Although effective treatments for both posttraumatic stress disorders (e.g. prolonged exposure, eye movement desensitisation, and reprocessing) and SUD (e.g. cognitive behavioural therapy, motivational enhancement techniques) are available, the literature for co-occurring posttraumatic stress disorders and SUD is still limited. The initial debate focused on the sequence of treatments. Early authors suggested that PTSD treatment should only be initiated after a period of abstinence had been achieved. More recently, preference is given to integrated treatments that conceptualise posttraumatic stress disorders and SUD as one large issue and plan treatment accordingly. While it is unclear if integrated treatments have a superior efficacy in patients with SUD and PTSD as compared to one efficacious treatment alone (Torchalla et al. 2012), the clinical needs of patients with SUD and posttraumatic stress disorders often make an integrated approach necessary. It has become widely accepted that the treatment of posttraumatic stress symptoms is a prerequisite for becoming abstinent in many patients. On the other hand, a certain stability of SUD is needed for some interventions, namely trauma exposure.

While SUD specific interventions are needed all along the way of treatment, a phase-based approach has been proven helpful to organise trauma-specific interventions. This approach follows the three stages of trauma therapy: (1) stabilising and managing responses; (2) grieving and processing traumatic memories; (3) reconnecting with the world. All patients need, and can benefit from, the present-focused interventions of the first phase of treatment. This phase includes getting a “road map” of the healing process, establishing safety, mobilising all available resources for healing, and learning how to regulate one’s emotions and manage symptoms. The second phase (including past-focused interventions, i.e. processing traumatic memories by means of trauma exposure) is essential to resolve symptoms of PTSD, but the moment when patients can enter this phase depends on the severity and complexity of the posttraumatic stress disorder. In more complex patients, a longer period of stabilisation will be necessary and in some patients (e.g. some patients with complex PTSD, DID or DDNOS) treatment is restricted to present-focused approaches. The following paragraphs summarise the available evidence for manualised present-focused and past-focused treatments of posttraumatic stress disorders in patients with SUD.

Different treatment approaches focusing on the present (i.e. providing skills training and psycho-education) can be of help in SUD patients with posttraumatic stress disorders. Some of these programmes, e.g. “Dialectical Behaviour Therapy for patients with SUD” (Dimeff and Linehan 2008) have not yet been evaluated in patients with PTSD. In a recent overview, van Dam et al. (2012) could identify four present-focused treatments for concurrent PTSD and SUD with at least one effectiveness study: CBT for PTSD in SUD treatment, Substance dependency-posttraumatic stress disorder therapy, Transcend, and Seeking Safety. They conclude that the first three programmes showed no effects or that it was not possible to draw firm conclusions because of the design of the respective studies. A relatively good evidence base exists for the manualised group treatment Seeking Safety (Najavits 2002). The programme has been evaluated in a larger number of studies including six randomised controlled trials (RCTs). It offers 25 topics to teach coping skills for PTSD and SUD in four domains (cognitive, behavioural, interpersonal, and case management) and has been translated into several European languages (see www.​seekingsafety.​org). An important assumption of the programme is that safety has the highest priority when recovering from posttraumatic stress disorders and SUD. Safety is defined as abstinence from substances, reduction in self-destructive behaviour, establishment of a network of supportive people, and self-protection from dangers associated with the disorders (e.g., HIV-risk, and domestic violence). Randomised controlled trials showed that Seeking Safety can lead to significant improvements in SUD and PTSD symptom severity. In the RCTs, the programme was more effective than the usual treatment for substance abuse and of equal effectiveness as other cognitive–behavioural interventions for SUD. In some of the controlled trials, Seeking Safety outperformed the control on PTSD but not SUD, in another on SUD but not PTSD, and in some on both PTSD and SUD (Najavits and Hien 2013). An advantage of the treatment is the possibility to provide clients with trauma-specific stabilisation in an early phase of treatment, when abstinence is difficult to achieve or to maintain. It can be followed, if necessary, by past-focused (i.e. exposure-based) treatments.