- Challenges to the Dimensional Approach
The publication of the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) has stirred many emotions both inside and outside of the psychiatric community. But when the director of the U.S. National Institute of Mental Health, Thomas Insel's, critique of the DSM-5 became public, even some antipsychiatrists were surprised. Insel argued that although the DSM's diagnostic categories have become the standard to obtain research grants and to conduct trials, they are not based on objective measures, lack validity, do not make accurate predictions about illness trajectory, and fail to map onto findings from neuroscience and genetics (Cuthbert & Insel, 2013; Hyman, 2010). In contrast with the diagnostic categories used in cases of "somatic" diseases, DSM categories were pieced together by various experts serving on DSM committees primarily to ensure reliability in diagnosis. The diagnostic categories then became de facto standards by which subjects are selected for research, which raises significant difficulties for testing their validity. Some argue that such reification of diagnostic categories has locked psychiatric research into an "epistemic prison" (Hyman, 2010), whereas others maintain that it has delayed efforts to associate disorder phenotypes with underlying neurobiological mechanisms, which might be one of the reasons why many pharmaceutical enterprises have reduced investments into research of mental disorders.
Responding to this state of affairs, the National Institute of Mental Health's research domain criteria (RDoC) project aims to "develop, for research purposes, new ways of classifying mental disorders based on dimensions of observable behavior and neurobiological measures" (Cuthbert & Insel, 2013, p. 1). The RDoC aims to follow other areas of medicine in moving toward "precision medicine" that relies on comprehensive specification of genetic and molecular characteristics (Cuthbert, 2015). In many of these areas, what was previously assumed to be a single disorder turned out to involve dissimilar pathophysiology and genetic precursors. In some of these cases, diagnosis and choice of treatment is no longer determined by, for instance, the organ involved, but rather by the fine-grained genetic profile of the disease. One main idea behind the RDoC is that constructing an experimental classification can provide a first step toward precision medicine for mental disorders, translating advances in behavioral and brain sciences into psychiatric assessment and treatment.
Although the RDoC has several "pillars," the target article by Fernandez emphasizes RDoC as an approach to experimental classification that cuts across current disorder categories. Instead of conceiving of mental disorders as more or less [End Page 77] bounded categories, the RDoC incorporates an explicitly dimensional approach that identifies risk factors at various points along the dimension that can support decisions about interventions. In part inspired by the RDoC, Fernandez argues that although the RDoC does not adequately take into account experiential features, phenomenological research can benefit from a broadly dimensional orientation, which is why he sets out to "motivate, outline, and illustrate a phenomenological–dimensional approach to psychiatric research and classification." The claim is that a dimensional orientation can serve as a guide to psychiatric research, help to avoid certain problems linked to current diagnostic categories, and even complement more traditional phenomenological approaches.
Fernandez starts out by sketching current phenomenological contributions and argues that these are aligned with categorial classifications to an extent that this might hamper efforts at dimensionally oriented research. Instead, the kind of dimensional framework that Fernandez aims to offer emphasizes that the dimensions do not presume the legitimacy of current diagnostic categories, and are neutral with respect to health and illness, to prevent imposing limitations on possibilities for research. Fernandez's phenomenological–dimensional approach does not start out from preexisting diagnostic categories, but from "core features of human existence" or "basic features of human subjectivity," as studied in the phenomenological tradition. Although the approach may or may not turn out to support current diagnostic categories, it does not depend on them.
most phenomenologists do rely on a shared set of conceptual distinctions to guide their investigations of human subjectivity. These concepts are what Heidegger refers to as "existentials" (1962), although they are also referred to as "transcendental," "essential," or "ontological" structures (Fernandez, 2014; forthcoming b). Each existential refers to a basic...