Background: A growing number of studies are questioning the validity of current DSM diagnoses, either as “discrete” or distinct mental disorders and/or as phenotypically homogeneous syndromes. In this study, we investigated how symptom domains in patients with a main diagnosis of obsessive-compulsive disorder (OCD), panic disorder (PD) and social anxiety disorder (SAD) coaggregate. We predicted that symptom domains would be unrelated to DSM diagnostic categories and less likely to cluster with each other as severity increases.
Methods: One-hundred eight treatment seeking patients with a main diagnosis of OCD, SAD or PD were assessed with the Dimensional Obsessive-Compulsive Scale (DOCS), the Social Phobia Inventory (SPIN), the Panic and Agoraphobia Scale (PAS), the Anxiety Sensitivity Index-Revised (ASI-R), and the Beck Depression and Anxiety Inventories (BDI and BAI, respectively). Subscores generated by each scale (herein termed “symptom domains”) were used to categorize individuals into mild, moderate and severe subgroups through K-means clusterization and subsequently analysed by means of multiple correspondence analysis.
Results: Broadly, we observed that symptom domains of OCD, SAD or PD tend to cluster on the basis of their severities rather than their DSM diagnostic labels. In particular, symptom domains and disorders were grouped into (1) a single mild “neurotic” syndrome characterized by multiple, closely related and co-occurring mild symptom domains; (2) two moderate (complicated and uncomplicated) “neurotic” syndromes (the former associated with panic disorder); and (3) severe but dispersed “neurotic” symptom domains.
Conclusion: Our findings suggest that symptoms domains of treatment seeking patients with OCD and anxiety disorders tend to be better conceptualized in terms of severity rather than rigid diagnostic boundaries.
Despite being listed in different chapters of DSM5 [i.e. obsessivecompulsive and related disorders (OCRDs) and anxiety disorders], obsessive-compulsive disorder (OCD), social anxiety disorder (SAD) and panic disorder (PD) are closely related to each other, as shown by shared symptoms (e.g. prominent fears and avoidant behaviors) , co-occurrence , common genetic factors [3,4], increased family accommodation , and treatment response to serotonin reuptake inhibitors  and exposure-based therapies . Also, the relationship between OCD, SAD and PD remain tacitly recognized in many diagnostic schemes. For instance, OCD and anxiety disorders were historically grouped under “neurotic” conditions by early theorists or simply as “anxiety disorders” across several DSM versions [8,9]. In DSM-5, despite their “splitting,” the OCRDs chapter remains straight after anxiety disorders as a recognition of their close relationship . Lastly, in more recent diagnostic models, such as the Hierarchical Taxonomy Of Psychopathology (HiTOP) , OCD and anxiety disorders are described as belonging to the same fear subfactor. Although OCD and anxiety disorders show many commonalities, the optimal way to conceptualize the association between these conditions is not completely clear (see Fig. 1).