Personality and psychopathology: the dangers of premature closure
Authors: PAUL S. LINKS
Journal: World Psychiatry (2011)

T. Widiger articulates the various relationships between personality and psychopathology as either influencing the appearance of one another, pathoplastic relationship; sharing a common etiology, spectrum relationship or having an etiologic role in causing one another, etiological relationship. Although he provides great clarity to these issues, he readily acknowledges that disentangling these relationships between personality and psychopathology is “a formidable task”. My commentary will mainly focus on the approach of the DSM-5 Personality and Personality Disorders Working Group (see www.dsm5.org) to resolving the issue of comorbidity between personality disorders (PDs) and clinical disorders (psychopathology or disorders on Axis I). I would suggest that their resolution to understanding the relationship is like diving into unknown waters; without some measurement of the depth, diving can place you in great danger. In 1980, the DSM-III first introduced a multiaxial system which placed PDs on a separate axis from clinical disorders. While not definitively distinguishing the two, this classification drew more attention to PDs both clinically and in research. Ever since, a growing body of literature has documented the extensive comorbidity between the two types of disorders. The use of the term comorbidity has been inconsistent and can be misleading if not defined explicitly. Feinstein 1 first defined this term as “any distinct additional clinical entity that has existed or that may occur during the clinical course of a patient who has the index disease under study”. In this definition, disorders are conceptualized as distinct; they can co-occur, but are not necessarily correlated. This is an important distinction, because correlation implies a causal or risk relationship. More contemporary models, such as those proposed by Krueger and Markon 2, suggest a multivariate comorbidity model to understand the relationship between liabilities and manifest disorders. James and Taylor 3 carried out their approach to study the structure of comorbidity regarding borderline personality disorder (BPD) and clinical disorders. They confirmed that BPD was associated with both internalizing and externalizing liabilities. However, these associations differed by gender, as externalizing was more strongly associated with BPD in men than women. James and Taylor demonstrated the complexity of the relationships between personality and psychopathology and the need to examine how other PDs fit into the internalizing and externalizing framework and with other liabilities. Changes to our current classification as proposed by the DSM-5 Personality and Personality Disorders Working Group appear driven by the desire to reduce the occurrence of comorbidity. The proposed solution seems to consider the observed co-occurrence as the result of diagnostic artifact and as harmful to our understanding of comorbidity. The proposed shedding of five PD diagnoses from DSM-IV to DSM-5 is in keeping with this argument, and several experts have supported this part of the proposal 4. However, the concern to remove spurious relationships between clinical disorders and PDs has trumped other considerations, including the purposes of clinical utility. Recent studies of comorbidity, including well-defined prospective cohort studies, have advanced our understanding of the clinical utility of making comorbid diagnoses. For example, the course of BPD is markedly affected by the presence or absence of comorbid substance abuse disorders. The absence of substance abuse disorders or the remission from a comorbid substance abuse disorder seems to predict earlier remission of BPD 5. Although many Axis I disorders are found to be comorbid with BPD, mood and anxiety disorders appear most interrelated. Specifically, remissions of BPD predict the remission of comorbid major depressive disorder (MDD) and lessen the risk of future MDD episodes in patients with BPD; thus, treatment interventions for BPD psychopathology must be undertaken to address the comorbid MDD 6. Based on the most comprehensive reviews, the treatment response of patients with comorbid MDD and PDs is twice as unsatisfactory as patients with MDD alone 7. Over and over again, the clinical utility of the concept of comorbidity has been supported and enhanced by the last decades of research. The clinical utility of studying the comorbidity between clinical disorders and PDs has not been adequately priorized when deciding on changes to our classification system. From a clinical utility perspective, the concept of comorbidity versus pure disorders may be analogous to studying malignant versus benign tumors. A malignancy is defined by its lack of boundaries and its system-wide impacts. These concepts, malignancy versus benign, are still incompletely understood, but they have very great clinical utility. Similarly, comorbidity of psychiatric disorders should not be hidden by our classification approach, but should be front and center in our approach to understanding individuals destined to have the poorest course, unsatisfactory treatment response and high rates of mortality. The radical changes proposed by the DSM-5 Personality and Personality Disorders Working Group have been criticized because they imply that we currently understand comorbidity adequately to generate a valid classification system. Their radical approach has also been criticized for moving away from the current diagnoses and all the recent empirical research based on these diagnoses that has accumulated over the last three decades. Finally, unlike the clarity provided in Widiger's paper, the DSM-5 Personality and Personality Disorders Working Group's proposal is highly complex and includes at least four separate diagnostic steps. The complexity of this proposal could hamper clinical utility and become a major barrier for clinicians attempting to diagnose personality disorders. Our field is going through a period of significant change and we must ensure that these transitions are carefully navigated. Premature closure on issues like comorbid diagnoses before we understand the waters depth could potentially be detrimental to our patients or mute our voice with policy and decision makers.