The importance of aberrant beliefs in obsessive-compulsive disorder and related conditions

What do obsessive-compulsive disorder (OCD), body dysmorphic disorder (BDD), hypochondriasis (HCH) and anorexia nervosa (AN) have in common? According to authors who argue that these disorders belong to the obsessive-compulsive spectrum, obsessions or obsession-like phenomena and compulsions or compulsion-like acts characterise OCD, BDD, HCH and AN. While this is to some extent true, strongly held and mood-unrelated, aberrant beliefs that are associated with these disorders may be a more striking, shared characteristic. In fact, such beliefs often make these conditions difficult to treat.

Belief specifiers instead of insight specifiers

In their debate article, Phillipou et al. (2017) note that a large proportion of individuals with AN have beliefs that can be qualified as delusions and overvalued ideas and propose diagnostic specifiers for AN similar to those that the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) has introduced for OCD and BDD: ‘with good or fair insight’, ‘with poor insight’ and ‘with absent insight/delusional beliefs’. Beta draft of the International Classification of Diseases, 11th Revision (ICD-11) proposes a distinction between subtypes with ‘fair to good insight’ and ‘poor to absent insight’ for OCD, BDD and HCH, but not for AN.

These insight specifiers confound the concepts of insight and beliefs. Insight is a broader concept that encompasses the ability to assess accurately one’s own beliefs, but should not be reduced to this ability. In contrast to good insight, poor or absent insight in DSM-5 denotes that the associated aberrant beliefs are held with strong conviction and, even more so, that they are fixed, i.e., they usually do not change despite evidence that disputes them. Therefore, it would be more adequate for diagnostic specifiers for OCD, BDD, HCH and AN to refer to the associated aberrant beliefs instead of insight.

Assessment of aberrant beliefs

The role of aberrant beliefs in OCD, BDD, HCH and AN has been controversial. A traditional categorical distinction between psychotic and non-psychotic disorders also meant that delusional beliefs could only be a feature of the former and never of the latter. As a result, the presence of delusions within conditions such as BDD and HCH was incompatible with the diagnoses of BDD and HCH as primarily non-psychotic disorders, with a proviso that psychosis, i.e., delusional disorder, is the proper diagnosis in such cases. Contrary to this view, the dimensional conceptualisation of beliefs on a continuum from normal beliefs through obsession-related beliefs and overvalued ideas to delusional beliefs has been proposed and already incorporated in the DSM-5 for disorders like OCD and BDD. According to this model, the presence of delusions does not invalidate a diagnostic designation of the psychopathological context in which delusions develop (i.e., OCD, BDD, HCH or AN), and these diagnoses are not replaced with a diagnosis of psychotic disorder. Although the dimensional model of aberrant beliefs that posits ‘delusionality’ of beliefs (Eisen et al., 1998) seems to dominate contemporary thinking, the jury is still out on whether it is also more accurate (e.g., Toh et al., 2017).

Considering these dilemmas, aberrant beliefs should be assessed in a way that avoids a premature conceptual closure. The Brown Assessment of Beliefs Scale (Eisen et al., 1998) was developed to measure the degree of ‘delusionality’ while also including aspects of insight into its assessment of beliefs and providing cut-off scores for distinguishing between normal beliefs and overvalued ideas and between overvalued ideas and delusions. The precision provided by this instrument is both attractive and deceptive. This is especially the case with the distinction between overvalued ideas and delusions, which is mainly quantitative and clinically very difficult. Indeed, the most important distinction from a clinical perspective is the one between delusional and nondelusional beliefs, with little or no room for consideration of overvalued ideas.

Several components of aberrant beliefs in OCD and related disorders have been identified: conviction, fixity, fluctuation (spontaneous changes in the level of conviction), resistance (effort made to reject the belief) and awareness that belief is unreasonable (Brakoulias and Starcevic, 2011). An instrument for assessment of aberrant beliefs based on this approach has undergone a preliminary validation (Brakoulias et al., in press).

Implications

Aberrant beliefs have important prognostic and treatment implications. Delusions are generally considered to suggest poorer prognosis and poorer response to treatment of OCD, BDD, HCH and AN. It seems reasonable to target delusions in such cases, but whether and how a standard treatment approach should be modified remains unclear. It is puzzling that delusional BDD does not respond to treatment with antipsychotics, whereas serotonin reuptake inhibitors may be equally effective for delusional and nondelusional BDD. Unlike pharmacological treatment for BDD, psychological treatments do take into account the presence of delusions. These quandaries are directly related to deficiencies in our understanding of the relationships between delusional and nondelusional forms of OCD, BDD, HCH and AN, calling for further research.

See Debate by Phillipou et al. 51: 563–564.