![Sample our Humanities journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/5939/TOC-Subject-Sample-2021-Humanities.jpg"})
ABSTRACT
Despite several criticisms surrounding the DSM classification in psychiatry, a significant bulk of research on mental conditions still operates according to two core assumptions: a) homogeneity, that is the idea that mental conditions are sufficiently homogeneous to justify generalization; b) additive comorbidity, that is the idea that the coexistence of multiple conditions in the same individual can be interpreted as additive. In this paper we take autism research as a case study to show that, despite a plethora of criticism, psychiatric research often continues to operate in accordance with this model. Then we argue that such a model runs into problems once facts about comorbidity are taken into account. Finally, we offer some suggestions on how to tackle the challenge raised by comorbidity and its impact on heterogeneity. To do so, we explore transdiagnostic stratification accounts and network models to show that combining these approaches can move us in the right direction.
Acknowledgement
We are grateful to Marta Jorba for her valuable feedback on earlier versions of this paper. We would also like to thank two anonymous referees of this journal for their constructive, encouraging, and engaging suggestions throughout the revision process. Their feedback helped us shape our own views. They deserve credit for much of what's worthy in this paper
Disclosure statement
No potential conflict of interest was reported by the author(s).
Notes
1. There are other unfortunate consequences of the DSM structure which we do not directly discuss here. One of them is the large number of Not Otherwise Specified (NOS) diagnoses, which are bound to exclude people who exhibit anomalous profiles and/or people who score right below the relevant diagnostic threshold (Lilienfeld & Treadway, Citation2016).
2. On some readings – see for instance, (Fellowes, Citation2021) – polythetic diagnoses are regarded as useful exactly because they make room for significant heterogeneity. We do not engage with this point directly here, as we are more interested in criticizing the standard approach as a whole, but it is worth mentioning that heterogeneity has at times been described as a positive feature of the current model.
3. In order to avoid pathologization, in this paper we use the labels “autistic spectrum conditions” (ASC) and “autism” interchangeably. Moreover, following the results reported in recent qualitative analyses of linguistic policies surrounding autism (Botha et al., Citation2020; Kenny et al., Citation2016), we use identity-first language in our discussion (i.e., “autistic” instead of “person with autism”). However, we acknowledge that “autism spectrum disorder” (ASD) is still widely used as a diagnostic label (American Psychiatric Association, Citation2013), and that ASC is not immune to criticism within the autistic community (Bervoets & Hens, Citation2020). We therefore use ASD only when directly referring to existing studies where such a label is employed.
4. To reiterate a point we already made elsewhere: whenever we use labels such as “ASC+ADHD” or “C+ COM”, we do so only for convenience and in reference to current practice, where conditions are usually treated in isolation or in additive combination with one another. In this respect – again – our argument starts from the conservative assumption that conditions may be characterized as identifiable entities which can be studied in isolation or in their interaction.
5. A note of caution here: we do not want to claim that comorbid conditions are complex systems. In fact, there may be relevant disanalogies between the typical complex systems (e.g., far from equilibrium physico-chemical systems, living beings, economical systems, societies, etc.) and systems formed by two or more conditions. However, we think that the analogy is illuminating because it helps us see that interactions between conditions and their characteristic symptoms are more complicated and unpredictable than they are currently taken to be.
6. There is a lively debate in the literature about emergence between those who understand emergence mainly as concerning unpredictability, and so as an epistemic issue, and those who embrace a stronger metaphysical position, according to which unpredictability signals metaphysical novelty (see, Vicente, Citation2013). We think we can sidestep this debate, as our point is that knowledge of putative basal conditions of individuals is not sufficient to describe such individuals. That is, we do not need to commit to metaphysical emergence for our argument to work.
7. Other transdiagnostic stratification projects which we cannot discuss in detail here – such as ROAMER (Schumann et al., Citation2014) and HiTOP (Kotov et al., Citation2017) – defend a broader view in this respect and attempt to complement the RDoC framework by adding constructs and dimensions that take into account more refined behavioral and developmental characterizations.
Additional information
Funding
Notes on contributors
Valentina Petrolini
Valentina Petrolini works as a Juan de la Cierva postdoctoral researcher at the University of the Basque Country, where she is also a member of the Language in Neurodiversity Lab (Lindy Lab). Her research focuses on the philosophy of psychiatry and psychology, and specifically on the boundary between mental health and pathology and on the notion of vulnerability in psychiatry. She has published on delusions, autism, schizophrenia, and depression in Philosophical Psychology, Review of Philosophy and Psychology, and Philosophy of Medicine.
Agustín Vicente
Agustín Vicente is Ikerbasque Professor at the University of the Basque Country. His main field of work has been that of the relations between language and thought and thought and language. He has published in venues such as Linguistics and Philosophy, The British Journal for Philosophy of Science, Mind & Language, Glossa, Philosophical Studies, and Nous. He currently works at the Language in Neurodiversity Lab (Lindy Lab) on autism and developmental language disorders.