differences when compared with usual treatment. Uncontrolled studies as to the effectiveness of Beck's cognitive therapy also showed a reduction in suicide risk and depressive symptoms, as well as a decrease in the number of BPD symptoms (Arntz, 1999; Beck, 2002; Brown, Newman, Charlesworth, Crits‐Christoph, & Beck, 2004). Moreover, the dropout rates during the first year were lower than normal (about 9%).
The first controlled study testing ST as developed by Young was conducted in the Netherlands, where ST was compared to TFP, a psychodynamic method from Kernberg and co‐workers (Giesen‐Bloo et al., 2006). This study started in 2000 and involved 3 years of treatment. ST showed more positive results than TFP in reduction of BPD symptoms, as well as other aspects of psychopathology and quality of life. In the follow‐up study, 4 years after the start of the treatment, 52% of the patients who started ST recovered from BPD, compared to 29% in TFP, while more than two‐thirds of ST participants showed clinically significant improvement in reducing BPD symptoms, compared to 52% in TFP. These percentages are impressive given that dropouts (even those due to somatic illness) were included in the study.
One of the most compelling results from this first randomized clinical trial (RCT) was that all BPD problems were reduced and not only conspicuous symptoms such as self‐harm. For instance, the patient's quality of life as a whole and her feeling of self‐esteem improved significantly. Thus, as a result of ST, all psychopathological characteristics of BPD, whether symptomatic or personality related, significantly improved. Similar results were found in a Norwegian series of case studies. When patients were measured post‐treatment, 50% no longer met the criteria for BPD and 80% appeared to have notably profited from the treatment (Nordahl & Nysæter, 2005).
Despite the high treatment costs, this first RCT on ST also demonstrated that ST is cost‐effective, as evidenced by a cost‐effectiveness analysis showing that ST is not only superior to TFP in effects, but also less costly. Moreover, compared with baseline, ST leads to a reduction of societal costs for BPD patients, so that the net effect was a reduction of costs, despite the costs involved in delivery of ST (van Asselt et al., 2008).
The question whether ST has similar effects when implemented in clinical practice was addressed in a study by Nadort et al. (2009). Results indicated that effectiveness and treatment retention were similar to those of the Giesen‐Bloo et al. (2006) trial. The study also addressed the issue whether therapists should provide a phone number that patients could use when in crisis outside office hours, as was originally prescribed by the protocol. As the results did not yield any evidence for a positive effect of this, providing such a phone contactability was deleted from the protocol. As will be seen, giving patients an email address that they can use to share experiences with their therapist outside office hours, without any obligation of therapists to respond immediately, has replaced the phone contactability.
There have been several studies completed now on ST for BPD (see Jacob & Arntz, 2013 and Sempertegui, Karreman, Arntz, & Bekker, 2013, for reviews), including studies on group‐ST (Farrell, Shaw, & Webber, 2009), the combination of individual and group‐ST (Dickhaut & Arntz, 2014; Fassbinder et al., 2016), and inpatient ST (Reiss, Lieb, Arntz, Shaw, & Farrell, 2014). Taken together, these studies indicate low dropout from treatment and high effectiveness of ST, that is not limited to BPD‐symptom reduction, but includes better social and societal functioning, better quality of life, and increased happiness. When dropout from ST for BPD is compared to other treatments, a multilevel survival meta‐analysis indicated that the dropout percentages reported so far in ST studies are remarkably smaller than those from other treatments (Arntz et al., 2020). The effectiveness of ST on measures of BPD‐severity and specific BPD‐traits is also high and the effect sizes tend to be significantly higher than in other treatments (Rameckers et al., 2020). However, so far only one larger RCT has been published that compared ST to another treatment (Giesen‐Bloo et al., 2006). It is necessary that more RCTs compare ST to other treatments, including treatment as usual and other specialized psychotherapies. One large international study comparing the combination of individual and group‐ST, group‐ST, and (optimal) treatment as usual for BPD was just completed when this book was finalized. The preliminary results indicated that ST was superior to treatment as usual in primary and secondary outcomes, and that especially the combined individual–group format was effective and associated with the highest treatment retention (Wetzelaer et al., 2014; Arntz et al., 2019). Another study that is currently underway is a German study comparing the combination of individual and group‐ST to DBT as treatments for BPD (Fassbinder et al., 2018). Both RCTs include not only focus on effectiveness, but also study cost‐effectiveness and experiences of patients.
What makes ST so acceptable for patients and what might explain its effectiveness? Qualitative studies into the views of patients and therapists have yielded some suggestions (de Klerk, Abma, Bamelis, & Arntz, 2017; Tan et al., 2018). First, the schema mode model is often mentioned as very helpful, offering both patients and therapists an easy to understand model of the patient's problems. This offers a meta‐cognitive understanding to patients and helps therapists to choose the right technique. Second, the therapeutic relationship, more specifically limited reparenting, is mentioned as particularly helpful. Third, experiential techniques are mentioned as particularly powerful. Fourth, on a more general level, the ST approach that focuses on deeper levels than symptoms and skills, linking developmental experiences and life‐long patterns to problems in the present, and addressing the historical roots of the patient's problems, is appreciated. Lastly, patients don't mention specific issues that are not focused on enough in ST, this in contrast to the findings by Katsakou et al. (2012), who concluded that patients found the focus of DBT and MBT too limited. However, some patients criticized that the newer ST models start to reduce session frequency in year 2, and stop treatment after 2 years, which is often viewed as too early. As to the comparison of group‐ST to the combination of individual and group‐ST, patients and therapists tend to favor the latter (from the results of the quantitative analysis of the international RCT we will learn whether this tendency is supported by treatment retention and effectiveness results).
To summarize, the results of empirical studies indicated that ST is a highly acceptable and effective treatment, which is cost‐effective despite its relative high intensity.
(Contra‐) Indications
There are certain disorders that can complicate the diagnosis of BPD, in particular bipolar disorder, psychosis (this refers to psychotic disorder, not a short‐term and reactive psychotic episode, which often occurs in BPD patients), and ADHD. The presence of these disorders complicates not only the diagnosis but might also interfere with treating BPD. However, if these disorders are very prominent, they will be the primary diagnosis, and BPD will be usually viewed as a secondary comorbidity. Usually these disorders have to be addressed first, before it is possible to focus on treating BPD.
Specific comorbid disorders, even if they are not viewed as primary, must be addressed before ST can be considered for BPD. These include very severe major depression, severe substance dependency in need of clinical detoxification, and anorexia nervosa. In addition, developmental disorders such as autism spectrum disorders require adaptation of ST. Recently therapists who work with these patients reported that they do have success with treating personality disorders with modified ST in this group when the autistic problems are not too severe. Research on ST for people with the combination of an autism spectrum disorder and a personality disorder has been conducted (Vuijk & Arntz, 2017). It should be stressed that the aim of such applications of ST is not to treat the autism spectrum disorder, but rather the personality disorder problems.
In the study by Giesen‐Bloo et al. (2006), antisocial personality disorder was also excluded. This was insisted upon by the TFP experts. However, pilot studies using ST with antisocial personality disorder have shown positive results, as an RCT comparing ST to treatment as usual in high security forensic hospitals, indicating ST can be an effective treatment for these patients (Bernstein, Arntz, & de Vos, 2007; Bernstein et al., 2020). However, for group application of ST for BPD, the inclusion of patients with specific comorbid antisocial personality traits might constitute a risk, if these patients cannot control their aggressive impulsive and act out in unpredictable ways to other group