McFarlane and Yehuda (2000) emphasise that post-traumatic stress disorder (PTSD) does not develop as a direct result of an event, but rather arises from the pattern of acute distress which is triggered by the event (McFarlane and Yehuda 2000, p. 143). It is assumed that different risk factors influence the development of PTSD. Objective risk factors include type, intensity and duration of the traumatic event, the extent of physical injury, whether the trauma was caused by people, and constantly being reminded of the event (triggering). Subjective risk factors include the unexpected occurrence of the traumatic event, a low level of personal control over what happens, guilt, and a lack of external help. Furthermore, youth or old age, belonging to a marginalised social group, low socio-economic status, a lack of social support and a family history of traumatic experiences all count as individual risk factors (Brewin et al. 2000; Ozer et al. 2003; Ehlers et al. 1998; Breslau et al. 1991).

According to Ehlers (1999), the prevalence of PTSD depends on the frequency of traumatic events and the nature of the trauma:

The lifetime prevalence across all cultures lies between 1 and 7 % (Flatten et al. 2001).

Trauma and migration can be connected in two different ways. Some people are faced with traumatic events associated with war, flight, expulsion and very often with sexual violence in their home countries; such experiences are often the reason for emigration to another country. On the other hand, people who leave their homeland can also be faced with a series of stressful events in the wake of this emigration.

Gilgen et al. (2005) examined various migrant groups in Switzerland and showed that conditions and events after migration have a serious impact on psychological well-being. Fifty percent of the surveyed Turkish/Kurdish migrants admitted to having experienced periods of extreme despair and suicidal thoughts after migration (ibid.), whereas before migration, only 12 % of them reported difficulties of this kind. Since then, several studies have provided evidence that migrants are at higher risk of experiencing traumatic experiences and developing PTSD. Al-Safar et al. (2001) examined three immigrant groups (Arabs, Iranians and Turks) in Stockholm and compared them with Swedish citizens. Of all the subjects surveyed, 89 % had experienced at least one trauma. The prevalence of PTSD was found to vary depending on group membership. Sixty-nine percent of Iranian immigrants, 59 % of the Arabs, 53 % of Turks and 29 % of Swedes were suspected of having PTSD (ibid.). The results indicate not only that multiple traumatic events increase the probability of developing PTSD, but also that belonging to an ethnic minority represents a risk factor (Brewin et al. 2000; Ozer et al. 2003; Ehlers et al. 1998; Breslau et al. 1991; Fearon et al. 2006; Veling et al. 2008; Selten et al. 2012).

Numerous studies confirm that PTSD in primary healthcare is common, but rarely diagnosed (Tagay et al. 2008). Instead, other comorbid mental disorders are diagnosed (Gomez-Beneyto et al. 2006; Katzman et al. 2005). A frequently cited reason for the poor rate of recognition for PTSD is the fact that patients themselves can rarely recognise or express the relationship between a past traumatic event and their illness (Carey et al. 2003; Munro et al. 2004). GPs therefore find themselves in a key position. The appropriate diagnosis and treatment of PTSD can significantly improve the outcome (Carey et al. 2003). The rate of trauma amongst refugees has been reported as being over 20 % (Gierlichs 2003); Gäbel et al. (2006) even speak of over 40 %. In a systematic review, the rate of PTSD amongst refugees and asylum seekers is described as being ten times more frequent than amongst the rest of the population (Crumlish and O’Rourke 2010).

The criteria described in ICD-10 and DSM-IV do not cover the entire spectrum of trauma-related disorders – there are a greater number of clinical disorders that can arise in connection with traumatic influences (Wöller et al. 2001). According to Sack (2004), a plethora of symptoms that would otherwise be classified as comorbid disorders can be drawn together into a unified etiological model with the help of the diagnostic category. Additional examination by an experienced clinician therefore forms an integral part of the diagnostic process.

A whole series exists of tried and tested questionnaires and structured interviews – such as the Impact of Event Scale Revision (IES-R), Structured Clinical Interview for DSM-PTSD (SCID-PTSD) or questionnaire for dissociative disorders (FDS) – with which to diagnose the consequences of extreme situations on mental health (Hofmann et al. 2001; Schützwohl 1997). In practice, these psychometric instruments are not generally suitable for the diagnosis of people from other cultures. The few available translations are rarely validated in their respective cultures, having been developed specifically for Western culture with regard to issues such as disease, symptoms, the concept of disease or mentality; this makes them only partially transferable to other cultures.

This highlights the dilemma of diagnostic testing in the field of intercultural psychiatry and psychotherapy (Birck et al. 2001). In addition, such methods cannot be used in cases where insufficient language skills are possessed. Özkan (2002) has pointed out the problematic areas in trauma-centred work with ethnic minorities. Schouler-Ocak et al. (2008) have insisted on the importance of cultural factors in intercultural treatment processes.

A useful picture of the physical and mental state of people with a migration background can often be gained through intercultural communication (Schouler-Ocak 1999; Schouler-Ocak et al. 2015). Knowledge of aspects which are specific to the relevant culture, disease, migration and the individual biography is essential. The use of a professionally trained, qualified interpreter as a linguistic and cultural mediator enables a mutual understanding in diagnosis and therapy (Salman 2001; Tuna and Salman 1999; Kluge 2011; Schouler-Ocak et al. 2015). Without such an understanding, taking a medical history, diagnosis and treatment are very difficult to manage; in a psychiatric-psychotherapeutic treatment context, these become virtually impossible.

In a pilot study in 12 large facilities, when asked about comprehension difficulties with patients with a migration background, teams of health professionals cited language-related problems in 27 % of cases, culture-related difficulties in 38 % of cases and both culture- and language-related communication problems in 44 % of cases (Koch et al. 2008). One example of the effects of such difficulties is shown by the results of a study of patients with a Turkish migration background and native-German patients in a women’s clinic in Berlin (Pette et al. 2004). Low competence in spoken German amongst the women with a Turkish migration background correlated with holding a poor level of information about the diagnosis and treatment, as well as a loss of information during an inpatient stay and the associated process of therapeutic education (ibid.). Communication problems in the therapeutic context also lead to fewer consultations with doctors, a poorer understanding of medical explanations, more frequent laboratory tests and increased utilisation of emergency departments (Yeo 2004).

In order to avoid misdiagnosis, inappropriate treatment and frustration, not only is good verbal communication necessary, but also the consideration of different explanatory models regarding the cause, course and cure of certain health problems (Kleinman 1980; Bhui and Bhugra 2002; Penka et al. 2008, 2012; Schouler-Ocak et al. 2015). The terms used for the description of the respective diseases can have a thoroughly different meaning in a specific cultural context. Explanatory models and expectations regarding the treatment are also subject to permanent variation connected to cultural changes, traditional elements, personal experiences and information from the social environment or the media (Heinz and Kluge 2011; Heinz et al. 2013).

In addition, patients and their relatives may have differing ideas and expectations during a period of illness with regard to the cause, symptoms, onset mechanisms, course of disease and potential treatment options (Kleinman 1980, 1988; Penka et al. 2008, 2012). Explanations can differ on the one hand between different cultural contexts and on the other hand due to class-, age- or gender-specific factors, for example (Vardar et al. 2012). These ideas and expectations are in a dynamic process and may also influence each other; experiences can therefore change too (Kleinman 1980; Heinz and Kluge 2011). In Appendix F of the DSM-VI-TR (Saß et al. 2003), there is a proposal for guidelines on taking a medical history and offering treatment in a culturally sensitive way. Its application allows the systematic consideration of the sociocultural background of patients with a migration background and should be used regularly in the work with them. The Cultural Formulation Interview (CFI) published in chapter on cultural formulation in DSM-5 can be used in research and clinical settings as potentially useful tool to enhance clinical understanding and decision-making and not as the sole basis for making a clinical diagnosis (APA 2013).

Intercultural treatment in Germany can only succeed if appropriate treatment can be ensured even for those with little knowledge of the German language. Even amongst those with a working knowledge of German for everyday life, not all people with a migration background have sufficient knowledge of German in the fields of body, health, well-being and sexuality (Razum et al. 2008). For health professionals, this situation necessitates the ability to work alongside interpreters (linguistic and cultural mediators); it also demands the availability of such mediators. This may, for example, involve community interpreting services such as those that exist in Berlin, but in larger hospitals, it is also conceivable that interpreting services might be offered by bilingual professional staff (Wesselmann 2000; Bahadir 2009).

The use of linguistic and cultural mediators should therefore take place as a matter of course when communication problems are evident. Guidelines for the professional use of linguistic and cultural mediators should be internalised not only by the mediators themselves, but also by the therapists (Bhugra et al. 2014; Schouler-Ocak et al. 2015). Interpreter-assisted treatment then becomes a viable option (Morina et al. 2010). In this context, a terminological ambiguity is inherent in the term ‘linguistic and cultural mediators’, as opposed to the more common term ‘interpreter’ (Penka et al. 2012); the term assumes a level of understanding in intercultural contexts which goes beyond the verbal (Penka et al. 2012; Qureshi et al. 2008, Qureshi and Collazos 2011). The aim is to recognise these cultural differences which are inherent to language differences and to make them accessible to the treatment process. According to Penka et al. (2012), in such cases, linguistic and cultural mediators are referred to for the cultural knowledge that they bring to the treatment setting and can help to clarify cultural differences and the resulting misunderstandings that can occur. The therapist must then integrate this knowledge into the therapeutic process (ibid.; Qureshi et al. 2008; Qureshi and Collazos 2011), a task for which an openness towards other symbolisations is a prerequisite (Kluge and Kassim 2006).

In this setting, it is therefore inappropriate to consider the interpreter simply as a mechanical, linguistic intermediary (Hsieh 2008; Qureshi et al. 2008; Qureshi and Collazos 2011; Haenel 2001); indeed, like the therapist, he/she is also involved in the transference of the patient and can in turn also trigger countertransference feelings. It is extremely important to take this into account too; otherwise, decisive factors which can influence the course of therapy might remain unnoticed and both the opportunity represented by the interpreter and the danger of trauma to the interpreters may be overlooked (Pross 2009). The therapeutic process can also be disrupted or stagnated when asymmetries in the relational patterns between the parties – therapist, interpreter and patient – occur. In such a setting, there are usually three rather than two players protagonists in the therapeutic space. These protagonists communicate in at least two different languages, creating a complex framework of levels of understanding and interaction that sometimes make such a setting difficult to comprehend (Qureshi et al. 2008, Qureshi and Collazos 2011; Hsieh 2008; Kluge 2011). In Germany, a lack of clarity in terms of the allocation of costs is a major cause for the low use of professional linguistic and cultural mediators (Kluge et al. 2012).

Not only cultural, but also linguistic, religious and ethnic misunderstandings may play a role in intercultural psychotherapy (Gün 2007). In particular, there is an indispensable need for ‘joining’ – the willingness of the therapist to empathise and enter into the lives of the patients and families with a migration background (Schlippe von and El Hachimi 2000; Erim and Senf 2002; Erim 2005). If the therapist and patient come from different cultural contexts, two types of bias may occur. On the one hand, the differences between the cultural contexts can be overemphasised – in extreme cases, a native therapist might even consider psychotherapy to be impossible. On the other hand, differences can be denied, and the influence of culturally defined social circumstances on the patients ignored. Both attitudes are viewed as problematic (Fisek and Schepker 1997; Bhugra and Mastrogianni 2004; Bhui and Bhugra 2002).

Intercultural trauma-centred psychotherapy refers to psychotherapeutic work with traumatised people with a migration background. It presupposes that the therapist has intercultural competence, this being understood as a component of social competence, since perception, judgement and action are always culturally conditioned (Grosch and Leenen 1998; Bhugra et al. 2014). According to Oesterreich and Hegemann (2010), openness, interest and respectful curiosity towards the unfamiliar represent the foundations of intercultural competence. Amongst other things, this includes working with linguistic and cultural mediators, observing and recognising the idioms of distress (locally typical patterns of symptoms), taking into account patients’ understandings of illness and expectations about treatment, and working out culturally appropriate explanations and treatment services (Kirmayer et al. 2008; Eiser and Ellis 2007; Betancourt et al. 2003; Odawara 2005). Trauma-centred psychotherapy consists of four phases (Sachsse 2004; Hofmann 2014; Reddemann and Sachsse 1997; Schouler-Ocak et al. 2008):