In this chapter we focused on function-oriented diagnosis, suggesting that case formulations constitute a viable alternative for classificatory DSM diagnosis. Function-oriented diagnosis does not aim at classification, but maps how problems and symptoms are embedded in someone’s wider functioning. Case formulations can be constructed on the basis of concrete material from clinical meetings, observation data, and information from psychological testing. The diagnostician discusses this material with the aim of making clear how problems are organized. The net result of function-oriented diagnosis is a narrative formulation that highlights the specificities of someone’s problems and strengths, which also indicates how a person’s functioning is embedded in relevant contexts.
In our discussion of the DSM we were very critical of the scientific status of this prestigious psychiatric diagnostic manual. We deemed its reliability and validity as insufficient. Is function-oriented diagnosis on this point so much more robust? The discussion around reflexivity, reliability, and validity in this chapter will have made it clear that this is not automatically the case. In diagnostic measurement tools arising from a positivistic research approach, reliability and validity are properties that appear to be inherent to the instrument itself. In large-scale studies researchers investigate how an instrument scores on a series of quality indicators, and on condition that users adhere to the testing protocol, one accepts that the findings of the large-scale study also apply to individual diagnostic situations. Case formulations, by contrast, are reasoned narrative constructions that do not simply fit within this research tradition. To assess the quality of case constructions we can appeal to methodological literature on qualitative research. This literature suggests that researchers need to work reflexively and give shape to the reliability and validity of their research through various methods. In this chapter I therefore propose that the diagnostician who works with case formulations should monitor and enhance the quality of her narratively based work, similar to the qualitative researcher. Function-oriented diagnosis requires a quality policy in which the reflexivity, reliability, and validity of the diagnostic process are established as well as possible. The principles and methods presented in this chapter may be used as a guide in this context.
Some readers may get the impression that with our plea for function- oriented diagnoses we are taking a step backward in time, since the common language of the DSM is no longer useful. For example, anyone working with the DSM knows the core diagnostic features of a serious depression. Is there no risk that abandoning the DSM will lead to confusion since a shared terminology to assess different kinds of psychopathology is therefore removed? This risk does exist but it is not insurmountable. On the one hand, the reassurance obtained through the common language of the DSM is largely an illusion. What is a shared language worth if the users of it give substantially different interpretations of the terminology with which it is made up? The poor results from the DSM-5 reliability studies show that there is little consistency in how diagnosticians handle the DSM. On the other hand, it is important that clinicians can clearly communicate with each other. To achieve this, psy-professionals need to pay more attention to the development of a common language around symptoms of psychopathology. In the DSM one hardly finds definitions or descriptions which make it clear, for example, what a hallucination exactly is and how it differs from a perceptual illusion, or what the core features of problematic forgetfulness in school children are. The DSM focuses too much on distinguishing syndromes. In the future we must pay more attention to the elaboration of a descriptive catalogue of symptoms.
Furthermore, our plea for function-oriented diagnosis can give the impression that we think of syndromes in a very relativistic way. Are all cases so unique that generalization is hardly possible? I do not think so. In line with Van Os (2013) or following Lacan’s differentiation between clinical structures (see Chap. 3), I believe that it is useful to distinguish groups of problems within the broad field of psychopathology. For example, it makes sense to differentiate between psychoses and neurotic conditions, and to discern addictions from neurocognitive disorders. When accepting broad groupings on the basis of typical core symptoms, we maintain a global picture of kinds of psychopathology, but immediately also bring into account that case-specific singularities are crucial.
Finally, our plea for function-oriented diagnosis might create uncertainty in terms of the differential diagnostic distinction between pathological and non-pathological functioning. Will function-oriented diagnostics not result in all functioning being problematized? I think that the reverse is true. In fact, the DSM is in danger of psychiatrizing behavior from which people do not seriously suffer (see Chap. 4). Case formulation enables a contextualized discussion of symptoms and painful issues in people’s lives, as well as strengths that add to their resilience. This is crucial in terms of establishing personalized interventions in mental health care.