Psychoanalysis has always been, according to its inventor, both a research endeavor and a therapeutic endeavor. Furthermore it is clear from Freud's autobiography that he prioritized the research aspect; he did not become a doctor because he wished to cure people in ill health (Freud, 2001 [1925]). His invention of the psychoanalytic approach to therapy, involving the patient lying down and associating freely, served a research purpose as much as a therapeutic purpose. Through free association, he would be able to gain unique insight in the human mind. Next, he had to find a format to report on his findings, and this would be the case study. The case study method already existed in medicine (Forrester, 2016), but Freud adjusted it considerably. Case studies in medical settings were more like case files, in which the patient was described or reduced to a number of medical categories: the patient became a case of some particular ailment (Forrester, 2016). In Freud's hands, the case study developed into Kranken Geschichten in which the current pathology of the patient is related to the whole of his life, sometimes even over generations.

Although Freud's case studies have demonstrably provided data for generations of research by analysts (Midgley, 2006a) and various scholars (Pletsch, 1982; Sealey, 2011; Damousi et al., 2015), the method of the case study has become very controversial. According to Midgley (2006b), objections against the case study method can be grouped into three arguments. First there is the data problem: case studies provide no objective clinical data (Widlöcher, 1994), they only report on what went right and disregard any confusion or mistakes (Spence, 2001). Second, there is the data analysis problem: the way in which the observations of the case study are analyzed lack validity; case studies confirm what we already know (Spence, 2001). Some go even so far to say that they are purely subjective: Michels calls case studies the “crystallization of the analyst's countertransference” (Michels, 2000, p. 373). Thirdly, there is the generalizability problem: it is not possible to gain generalizable insight from case studies. Reading, writing and presenting case studies has been described as being a group ritual to affirm analysts in their professional identity, rather than a research method (Widlöcher, 1994).

These criticisms stand in contrast to the respect gained by the case study method in the last two decades. Since the 1990s there has been an increasing number of psychoanalytic and psychodynamic clinical case study and empirical case studies being published in scientific journals (Desmet et al., 2013; Cornelis et al., in press). It has also been signaled that the case study method is being revived more broadly in the social sciences. In the most recent, fifth edition of his seminal book on case study research, Yinn (2014) includes a figure showing the steady increase of the frequency with which the term “case study research” appears in published books in the period from 1980 to 2008.

In addition to the controversy about the case study method, psychoanalysis has developed into a fragmented discipline. The different psychoanalytic schools share Freud's idea of the unconscious mind, but they focus on different aspects in his theoretical work. Some of the schools still operate under the wings of the International Psychoanalytic Association, while others have established their own global association. Each school is linked to one or several key psychoanalysts who have developed their own version of psychoanalysis. Each psychoanalytic school has a different set of theories but there are also differences in the training of new psychoanalysts and in the therapeutic techniques that are applied by its proponents.

Based on this heterogeneity of perspectives in psychoanalysis, a research group around the Single Case Archive investigated the current status of case study research in psychoanalysis (Willemsen et al., 2015a). They were particularly interested to know more about the output and methodology of case studies within the different psychoanalytic schools.

In order to investigate and compare case studies from different psychoanalytic schools, we first had to find a way of identifying to which school the case studies belonged. This is very difficult to judge straightforwardly on the basis of the published case study: the fact that someone cites Winnicott or makes transference interpretations doesn't place him or her firmly within a particular psychoanalytic school. The best approach was to ask the authors themselves. Therefore, we contacted all case study authors included in the Single Case Archive (since the time of our original study in 2013, the archive has expanded). We sent emails and letters in different languages to 445 authors and received 200 replies (45% response rate). We asked them the following question: “At the time you were working on this specific case, to which psychoanalytic school(s) did you feel most attached?” Each author was given 10 options: (1) Self Psychology (1.a Theory of Heinz Kohut, 1.b Post-Kohutian Theories, 1.c Intersubjective psychoanalysis), (2) Relational psychoanalysis, (3) Interpersonal psychoanalysis, (4) Object relational psychoanalysis (4.a Theory of Melanie Klein, 4.b Theory of Donald W. Winnicott, 4.c Theory of Wilfred R. Bion, 4.d Theory of Otto F. Kernberg), (5) Ego psychology (or) “Classic psychoanalysis” (5.a Theories of Sigmund Freud, 5.b Ego psychology, 5.c Post-Ego psychology), (6) Lacanian psychoanalysis, (7) Jungian psychoanalysis, (8) National Psychological Association for Psychoanalysis (NPAP) related theory, (9) Modern psychoanalysis related to the Boston or New York Graduate School of Psychoanalysis (BGSP/NYGSP), (10) Other. Respondents could indicate one or more options.

Analysis of the responses indicated that the two oldest schools in psychoanalysis, Object-relations psychoanalysis and Ego psychology, dominate the field in relation to case studies that are published in scientific journals. More than three quarters of all case study authors (77%) reported these schools of thought to be the ones with which they considered themselves most affiliated. Three more recent schools were also well-represented among case studies: Self Psychology, Relational Psychoanalysis, and Interpersonal Psychoanalysis. Lacanian Psychoanalysis, Jungian Psychoanalysis, NPAP related Theory and Modern Psychoanalysis related to the BGSP/NYGSP were only rarely mentioned by case study authors as their school of thought. This does not mean that clinicians or researchers within these latter schools do not write any case studies. It only means that they publish few case studies in the scientific journals included in ISI-ranked journals indexed in Web of Science. But they might have their own journals in which they publish clinical material.

Our survey demonstrated that the majority of case study authors (59%) feel attached to more than one psychoanalytic school. This was in fact one of the surprising findings in our study. It seems that theoretical pluralism is more rule than exception among case study authors. There were some differences between the psychoanalytic schools though in terms of pluralism. Case study authors who feel attached to Self Psychology and Interpersonal Psychoanalysis are the most pluralistic: 92 and 86%, respectively also affiliate with one or more other psychoanalytic schools. Case study authors who feel attached to Object Relations Psychoanalysis are the “purest” group: only 69% of them affiliate with one or more other psychoanalytic schools.

We were not really surprised to find that Object Relations psychoanalysis and Ego psychology were the most dominant schools in the field of psychoanalytic case studies, as they are very present in European, Latin-American and North-American psychoanalytic institutes. We were more surprised to find such a high degree of pluralism among these case study authors, given the fact that disputes between analysts from different schools can be quite ardent (Green, 2005; Summers, 2008). Others have compared the situation of psychoanalytic schools with the Tower of Babel (Steiner, 1994).

It has been argued that the case study method contributes to the degree of theoretical pluralism within psychoanalysis. The reason for this is situated in the reasoning style at the basis of case study research (Chiesa, 2010; Fonagy, 2015). The author of a psychoanalytic case study makes a number of observations about the patient within the context of the treatment, and then moves to a conclusion about the patient's psychodynamics in general. The conclusion he or she arrives at inductively gains its “truth value” from the number and quality of observations it is based on. This style of reasoning in case study research is very similar to how clinicians reason in general. Clinicians look for patterns within patients and across patients. If they make similar observations in different patients, or if other psychoanalysts make similar observations in their patients, the weight of the conclusion becomes greater and greater. The problem with this reasoning style is that one can never arrive at definite conclusions: even if a conclusion is based on a large number of observations, it is always possible that the next observation disconfirms the conclusion. Therefore, it could be said, it is impossible to attain “true” knowledge.

The above argument is basically similar to objections against any kind of qualitative research. To this, we argue with Rustin (2003) that there is not one science and no hierarchy of research methods. Each method comes with strengths and weaknesses, and what one gains in terms of control and certainty in a conventional experimental setup is lost in terms of external validity and clinical applicability. Numerous researchers have pleaded for the case study approach as one method among a whole range of research methods in the field of psychoanalysis (Rustin, 2003; Luyten et al., 2006; Midgley, 2006b; Colombo and Michels, 2007; Vanheule, 2009; Hinshelwood, 2013). Leuzinger-Bohleber makes a distinction between clinical research and extra-clinical research (Leuzinger-Bohleber, 2015). Clinical research is the idiographic type of research conducted by a psychoanalyst who is working with a patient. Unconscious phantasies and conflicts are symbolized and put into words at different levels of abstraction. This understanding then molds the perception of the analyst in subsequent clinical situations; even though the basic psychoanalytic attitude of “not knowing” is maintained. The clinical case study is clinical research par excellence. Extra-clinical research consists in the application of different methodologies developed in the natural and human sciences, to the study of the unconscious mind. Leuzinger-Bohleber refers to empirical psychotherapy research, experimental research, literature, cultural studies, etc. We believe that the clinical case study method should step up and claim its place in psychoanalytic research, although we agree that the method should be developed further. This paper and a number of others such as Midgley (2006b) should facilitate this methodological improvement. The clinical research method is very well-suited to address any research question related to the description of phenomena and sequences in psychotherapy (e.g., manifestation and evolution of symptoms and therapeutic relationship over time). It is not suitable for questions related to causality and outcome.

We also want to point out that there is a new evolution in the field of psychotherapy case study research, which consists in the development of methodologies for meta-studies of clinical case studies (Iwakabe and Gazzola, 2009). The evolution builds on the broader tendency in the field of qualitative research to work toward integration or synthesis of qualitative findings (Finfgeld, 2003; Zimmer, 2006). The first studies which use this methodology have been published recently: Widdowson (2016) developed a treatment manual for depression, Rabinovich (2016) studied the integration of behavioral and psychoanalytic treatment interventions, and Willemsen et al. (2015b) investigated patterns of transference in perversion. The rich variety of research aims demonstrates the potential of these meta-studies of case studies.

The second research question of our study (Willemsen et al., 2015a) concerned the methodological, patient, therapist, and treatment characteristics of published psychoanalytic case studies. All studies included in the Single Case Archive are screened by means of a coding sheet for basic information, the Inventory of Basic Information in Single Cases (IBISC). The IBISC was designed to assess the presence of basic information on patient (e.g., age, gender, reasons to consult), therapist (e.g., age, gender, level of experience), treatment (e.g., duration, frequency, outcome), and the methodology (e.g., therapy notes or audio recoding of sessions). The IBISC coding revealed that a lot of basic information is simply missing in psychoanalytic case studies (Desmet et al., 2013). Patient information is fairly well-reported, but information about therapist, treatment and methodology are often totally absent. Training and years of experience are not mentioned in 84 and 94% of the cases, respectively. The setting of the treatment is not mentioned in 61% of the case studies. In 80% of the cases, it was not mentioned whether the writing of the case studies was on the basis of therapy notes, or audiotapes. In 91% of the cases, it was not mentioned whether informed consent was obtained.

Using variables on which we had more comprehensive information, we compared basic information of case studies from different psychoanalytic schools. This gave us a more detailed insight in the type of case studies that have been generated within each psychoanalytic school, and into the difference between these schools in terms of the kind of case study they generate. We found only minimal differences. Case studies in Relational Psychoanalysis stand out because they involve older patients and longer treatments. Case studies in Interpersonal Psychoanalysis tend to involve young, female patients and male therapists. Case study authors from both these schools tend to report on intensive psychoanalysis in terms of session frequency. But for the rest, it seems that the publication of case studies throughout the different psychoanalytic schools has intensified quite recently.

One of the main problems in using psychoanalytic case studies for research purposes is the enormous variability in quality of reporting and inconsistency in the provision of basic information about the case. This prevents the reader from contextualizing the case study and it obstructs the comparison of one case study with another. There have been attempts to provide guidelines for the writing of case studies, especially in the context of analytic training within the American Psychoanalytic Association (Klumpner and Frank, 1991; Bernstein, 2008). However, these guidelines were never enforced for case study authors by the editors from the main psychoanalytic journals. Therefore, the impact of these guidelines on the field of case study research has remained limited.

Here at the end of our focused review, we would like to provide guidelines for future case study authors. Our guidelines are based on the literature and on our experience with reading, writing, and doing research with clinical case studies. We will include fragments of existing case studies to clarify our guidelines. These guidelines do not provide a structure or framework for the case study; they set out basic principles about what should be included in a case study.

As Yinn (2014) has argued for the social sciences, the case study method is the method of choice when one wants to study a phenomenon in context, especially when the boundaries between the phenomenon and the context are fussy. We are convinced that the same is true for case study methodology in the fields of psychoanalysis and psychotherapy. The current focused review has positioned the research method within these fields, and has given a number of guidelines for future case study researchers. The authors are fully aware that giving guidelines is a very tricky business, because while it can channel and stimulate research efforts it can as well-limit creativity and originality in research. Moreover, guidelines for good research change over time and have to be negotiated over and over again in the literature. A similar dilemma is often pondered when it comes to qualitative research (Tracy, 2010). However, our first impetus for providing these guidelines is pedagogical. The three authors of this piece are experienced psychotherapists who also work in academia. A lot of our students are interested in doing case study research with their own patients, but they struggle with the methodology. Our second impetus is to improve the scientific credibility of the case study method. Our guidelines for what to include in the written account of a case study, should contribute to the improvement of the quality of the case study literature. The next step in the field of case study research is to increase the accessibility of case studies for researchers, students and practitioners, and to develop methods for comparing or synthesizing case studies. As we have described above, efforts in that direction are being undertaken within the context of the Single Case Archive.

JW has written paragraphs 1–4; ER and JW have written paragraph 5 together; SK has contributed to paragraph 5 and revised the whole manuscript.