Challenging use of the insight specifier for body dysmorphic disorder

In the latest edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), body dysmorphic disorder (BDD) is characterised by preoccupation(s) with perceived flaws in physical appearance that are not visible or appear slight to others, alongside repetitive behaviours or mental acts that serve to (temporarily) ameliorate said appearance-related concerns (American Psychiatric Association, 2013). A similar definition was adopted in the updated International Classification of Diseases (ICD), 11th Revision, with added mention of experiences of excessive self-consciousness alongside ideas of reference (World Health Organization, 2018). Across both classification systems, the nosological status of BDD has been challenging and fraught with inconsistencies. It was first conceived as ‘dysmorphophobia’ by Italian physician, Enrico Morselli, in the late 19th century and then described as a compulsive neurosis and obsessional shame about the body by early psychiatrists, Emil Kraepelin and Pierre Janet, but only officially introduced into the 1987 and 1979 editions of Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised (DSM-III-R) and ICD-9, respectively. At that point, its initial monikers associated with hypochondriasis (e.g. ‘beauty hypochondria’) were likely instrumental in linking it among the somatoform disorders. A prominent feature of BDD is that the appearance-related preoccupations often reach delusion proportions. In fact, a high proportion of patients with BDD demonstrate delusional conviction and referential delusions, but insight can vary. In ensuing iterations of its nosological classification, the assignment of non-delusional BDD within the somatoform disorders remained, but uniquely its delusional variant was separately classified as a psychotic disorder (i.e. delusional disorder, somatic subtype), with a double-coding approach subsequently required in Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR). The approach in ICD-10 was even more complex, with BDD falling into multiple possible diagnoses involving hypochondriacal disorder, schizotypal disorder or (other persistent) delusional disorder (Veale and Matsunaga, 2014). Recent updates to these classification systems now designate BDD as a standalone diagnosis, but grouped within the obsessive-compulsive and related disorders (OCRDs) in DSM-5 as well as in ICD-11. Along with this move came the recognition that its non-delusional and delusional variants constitute a single disorder differentiated along a spectrum of insight. Consequently, an insight specifier was introduced – this comprises three levels (good or fair, poor, or absent/delusional beliefs) in DSM-5 and two levels (fair to good or poor to absent) in ICD-11. Yet there is reason to question this approach on three fronts: (1) from a theoretical perspective, (2) what this means for nosology and (3) its impact on clinical utility in terms of treatment. First, the prevailing model of multidimensional insight theorises this construct as comprising three discrete facets involving the recognition that one has a mental illness, recognises the attribution of unusual mental events as pathological and accepts the need for treatment (David, 1990). In contrast, the insight specifier for BDD is seemingly geared towards assessing level of conviction; individuals with fair insight tend to embrace overvalued ideas susceptible to disconfirmation, whereas those endorsing poor insight hold extreme, unwavering conviction. From this perspective, more accurate terminology would perhaps evoke use of a conviction specifier. The nature of delusional beliefs also warrants further consideration. A multidimensional assessment of insight based on principal preoccupation showed that levels of conviction and fixity of ideas in BDD were significantly higher than those in obsessive-compulsive disorder (OCD) and were in fact similar to schizophrenia (Toh et al., 2017). On the contrary, what was termed insight, or the ability to attribute beliefs to a psychological cause (David, 1990), was significantly lower in BDD relative to people with OCD or schizophrenia. Furthermore, referential delusions Challenging use of the insight specifier for body dysmorphic disorder