Welcome to the research page of the international EDT community!
EDTs have a solid research base, building on many process and outcome research findings. Many international researchers have examined different types EDT for different types of disorders and have published studies on the process and outcome of EDT, using quantitative and qualitative analyses, as well as many reviews and meta-analyses.
The IEDTA research committee members are Allan Abbass (Canada), Susan Hajkowski (UK), Peter Lilliengren (Sweden), Deborah Pollack (USA), & Katie Aafjes-van Doorn (USA).
The aim of the research committee is to bridge the gap between research and practice by communicating about past and current EDT research on the website, academic EDT listserv, and at the next conference in Venice. Ultimately, we hope to generate a space where all clinicians can be part of research and reap the benefits of it. We hope to get the word out about the evidence-base of EDT.
If you are interested in research and teaching from/by our EDT committee, please consider joining our listserv subgroup.
If you have any suggestions, questions or research ideas, please email research@iedta.net
We would love to hear from you,
Katie Aafjes-van Doorn
Chair of the IEDTA Research Committee
Meta-analyses of Randomized Controlled trials in Short term/long-term psychodynamic therapy

ISTDP-specific reviews & meta-analyses
Abbass, A. A., Kisely, S. R., Town, J. M., Leichsenring, F., Driessen, E., De Maat, S., Gerber, A., Dekker, J., Rabung, S., Rusalovska, S., & Crowe, E. (2014). Short-term psychodynamic psychotherapies for common mental disorders. Cochrane Database of Systematic Reviews. https://doi.org/10.1002/14651858.CD004687.pub4
Abbass, A., Town, J., & Driessen, E. (2012). Intensive Short-Term Dynamic Psychotherapy: A Systematic Review and Meta-analysis of Outcome Research: Harvard Review of Psychiatry, 20(2), 97–108. https://doi.org/10.3109/10673229.2012.677347
Abbass, A., Town, J. M., & Driessen, E. (n.d.). Intensive Short-Term Dynamic Psychotherapy: A Review of the Treatment Method and Empirical Basis. 10.
Caldiroli, A., Capuzzi, E., Riva, I., Russo, S., Clerici, M., Roustayan, C., Abbass, A., & Buoli, M. (2020). Efficacy of intensive short-term dynamic psychotherapy in mood disorders: A critical review. Journal of Affective Disorders, 273, 375–379. https://doi.org/10.1016/j.jad.2020.04.002
Lilliengren, P., Johansson, R., Lindqvist, K., Mechler, J., & Andersson, G. (2016). Efficacy of experiential dynamic therapy for psychiatric conditions: A meta-analysis of randomized controlled trials. Psychotherapy,53(1), 90–104. https://doi.org/10.1037/pst0000024
ISTDP RCTs
(collated by Peter Lilliengren)
EDT researcher and IEDTA research committee member Peter Lilliengren is keeping a log of all conducted RCTs on EDT therapies. (see link below).
The list now in includes 256 identified studies – an increase of 11 studies since the last version in December 2019! Some older studies have been added along with new ones. There is a Excel version linked on the ResearchGate page too. Please let us know if you miss any study on the list or if you find faulty information on it.
Research@iedta.net
ISTDP Research on the effect of the Trial Therapy
(collated by Allan Abbass)
Following are abstracts of 6 outcome studies of the Trial Therapy. All the studies point to benefits of the interview. The first study was all my trial therapies and the second was compared to standard intake interviews I had done. The third was trial therapies using a similar model and can be considered a replication on the first study. The 4th study is a process analysis of change per 10 minutes within the trial therapy. The 5th is a large sample study with many different therapists overcoming the issue of one expert doing the interview: it found outcomes in the trial related to degree of emotional experiencing an interesting finding. Finally, a large subset of these cases were analyzed separately and found to show large measurable reductions in health care costs in long follow-up.
Abbass A, Joffres M, & Ogrodniczuk J (2008). A Naturalistic Study of Intensive Short-Term Dynamic Psychotherapy Trial Therapy. Brief Treatment and Crisis Intervention. 8:164–170.
The objective is to study the effectiveness of Intensive Short-Term Dynamic Psychotherapy (ISTDP) trial therapies. In a tertiary psychotherapy service, Brief Symptom Inventory (BSI) Inventory of Interpersonal Problems (IIP) medication use, and need for further treatment were evaluated before versus 1-month post trial therapy in a sequential series of 30 clients. Trial therapies were interviews with active focus on emotions and how they are experienced. The interviews resulted in statistically significant improvements on all BSI subscales and one of the IIP subscales. One-third of clients required no further treatment, seven stopped medications, and two returned to work following trial therapy. The ISTDP trial therapy appeared to be clinically effective and cost effective. Future research directions are discussed.
Abbass, A., Joffres, M., & Ogrodniczuk, J. (2009). Intensive Short-term Dynamic Psychotherapy Trials of Therapy: Qualitative Description and Comparison to Standard Intake Assessments, AD HOC Bulletin of STDP, page 6-13
Objective: To compare Intensive Short-Term Dynamic Psychotherapy (ISTDP) trial therapy consultations to standard intake interviews. Design: Non-randomized clinical trial design. Methods: Thirty sequential ISTDP trial therapies were compared to 20 traditional intake assessment interviews using blind ratings of videotape samples. Brief Symptom Inventory and Inventory of Interpersonal Problems scores were compared pre and post interview. Need for follow-up treatment, medication use and work functioning were also compared between groups. Results: Trial therapies were clearly distinguishable from standard intake assessments. The trial therapy resulted in statistically significant improvements on all BSI subscales. In the follow-up interview, one third (10) of individuals in the trial therapy group required no further treatment, 7 were able to stop 11 psychotropic medications, and 2 were able to return to work. Conclusions: ISTDP trial therapy appears to be a distinct therapeutic assessment procedure that results in superior benefits compared to traditional intake assessments. Confirmation of these findings will require a randomized trial.
Aafjes-van Doorn K, Macdonald J, Stein M, Cooper A, Tucker S (2014). Experiential Dynamic Therapy: A Preliminary Investigation Into the Effectiveness and Process of the Extended Initial Session Journal of Clinical Psychology. 70(10), 914-923.
Objective: This study explored whether patients in specialist psychology services made early gains on theoretically relevant therapeutic processes and outcomes after a trial therapy session (one 2- to 3-hour initial Experiential Dynamic Therapy session). Method: This practice-based, nonrandomized trial used a pre–post design. Thirty-one patients (23women, average age of 37) completed standardized measures of symptoms of general distress, interpersonal functioning, self-compassion, and remoralization before and after the trial therapy session. Video recordings of the sessions’ therapy process were rated on the Achievement of Therapeutic Objectives Scale. Results: After the trial therapy session, patients reported a significant increase in remoralization and self-compassion and a significant decrease in symptoms of general distress but not interpersonal problems. Process ratings were not significantly associated with improvement on these outcome measures. Conclusions: This initial positive effect could be due to the session or an effect of time or placebo. Future research using active control conditions is warranted.
Aafjes-van Doorn, K., Lilliengren, P., Cooper, A., Macdonald, J., & Falkenström, F. (2017). Patients’ affective processes within initial experiential dynamic therapy sessions. Psychotherapy, 54(2), 175-183.
Abstract: Research has indicated that patients’ in-session experience of previously avoided affects may be important for effective psychotherapy. The aim of this study was to investigate patients’ in-session levels of affect experiencing in relation to their corresponding levels of insight, motivation, and inhibitory affects in initial Experiential Dynamic Therapy (EDT) sessions. Four hundred sixty-six 10-min video segments from 31 initial sessions were rated using the Achievement of Therapeutic Objectives Scale. A series of multilevel growth models, controlling for between-therapist variability, were estimated to predict patients’ adaptive affect experiencing (Activating Affects) across session segments. In line with our expectations, higher within-person levels of Insight and Motivation related to higher levels of Activating Affects per segment. Contrary to expectations, however, lower levels of Inhibition were not associated with higher levels of Activating Affects. Further, using a time-lagged model, we did not find that the levels of Insight, Motivation, or Inhibition during one session segment predicted Activating Affects in the next, possibly indicating that 10-min segments may be suboptimal for testing temporal relationships in affective processes. Our results suggest that, to intensify patients’ immediate affect experiencing in initial EDT sessions, therapists should focus on increasing insight into defensive patterns and, in particular, motivation to give them up. Future research should examine the impact of specific inhibitory affects more closely, as well as between-therapist variability in patients’ in-session adaptive affect experiencing.
Abbass, A, Town, J. Ogrodniczuk, J. Joffres, M. & Lilliengren, P. (2017). Intensive Short-Term Dynamic Psychotherapy Trial Therapy Effectiveness and Role of “Unlocking the Unconscious” J Nerv Ment Dis, 205: 453–457.
Abstract: This study examined the effects of trial therapy interviews using intensiveshort-term dynamic psychotherapy with 500 mixed sample, tertiary center patients. Furthermore, we investigated whether the effect of trial therapy was larger for patients who had a major unlocking of the unconscious during the interview compared with those who did not. Outcome measures were the Brief Symptom Inventory (BSI) and the Inventory of Interpersonal Problems (IIP), measured at baseline and at 1-month follow-up. Significant outcome effects were observed for both the BSI and the IIP with small to moderate preeffect/posteffect sizes, Cohen’s d = 0.52 and 0.23, respectively. Treatment effects were greater in patients who had a major unlocking of the unconscious compared with those who did not. The trial therapy interview appears to be beneficial, and its effects may relate to certain therapeutic processes. Further controlled research is warranted.
Abbass A, Kisely S, & Town J (2018). Cost-Effectiveness of Intensive Short-Term Dynamic Psychotherapy Trial Therapy. Psychotherapy and Psychosomatics, 87(4), 255-257
Main Methods:We included 344 patients, of whom 63.7% were female, 77.4% were aged 25–60 years, and 78.9% were from the urban area of Halifax (NS, Canada). They were provided trial therapy by 10 different therapists who were experienced in the ISTDP model. The interviews themselves cost an average of approximately CAD 187 each. The interviews were considered overall to be adherent to the model with ratings of 3.3 (standard deviation, SD 0.8) on a 4-point scale. Patients’ symptoms reflected a range of complexity with 83 subjects having fragile character structure with dissociative features, 91 having high resistance, 60 having moderate resistance, and only 5 having low resistance, based on therapist ratings of psychodiagnostic functioning [8]. Diagnostically, 57.3% had somatic symptom disorders, 56.9% had an anxiety disorder, 49.3% had a personality disorder, and 33.1% had major depression.
Main Results:Baseline physician and hospital costs were CAD 915 (SD 748) and CAD 3,958 (SD 13,779), respectively (Table 1). Both of these were greater than normal population costs of CAD 600 and 1,389, respectively [7]. Physician costs dropped by CAD 168 per person (p < 0.001) the first year and further reduced to below population means in the second, third, and fourth follow-up years (Table 1). Hospital costs dropped markedly by CAD 988 after the first year and reduced further to below population means in the second, third, and fourth follow-up years. Likely due to a skewed data distribution, the difference between hospital costs 1 year before and after ISTDP was not statistically significant (p = 0.18). Because of data access limits, statistical comparisons between the second to fourth years versus the first year are not available. The overall average cost reductions per person versus baseline were 25.8, 62.8, 66.5, and 67.3%, respectively, reflecting a total per person difference of CAD 10,841 per person, vastly exceeding the cost of the single trial therapy interview itself.
