Problems with the Current Diagnostic System
Problems with the Current Diagnostic System1
No diagnostic system can be perfectly constructed. Therefore, it should come as no surprise that the current DSM diagnostic system for personality disorders has its fair share of problems. Researchers and clinicians have identified several, significant, diagnostic difficulties that can be summarized as follows:
1. The DSM uses a categorical approach vs. a dimensional approach to personality disorder diagnosis2.
2. The DSM does not account for the relative importance of various symptoms, and the descriptions of symptom criteria are overly broad. This means that patients diagnosed with the same disorder may have very dissimilar clinical presentations.
3. There is a high degree of overlap or co-occurrence of Axis II personality disorders with each other, and other Axis I mental disorders.
1. A categorical versus dimensional approach to diagnosis3:
The classification system in DSM IV-TR (APA, 2000) is a categorical diagnostic system in that it assumes each personality disorder is a separate and distinct category; i.e., separate from other personality disorders, and distinct from "normal" personalities. But an alternative way of viewing personality disorders is called a dimensional or continuous approach. In contrast to the categorical system, a dimensional system would view various personality features along several continuous dimensions (or continuums). In this dimensional approach, personality disorders would represent the extremes along a continuum of otherwise normal, healthy personality dimensions. Let's contrast these two classification systems a little further and discuss the implications of each.
In the current DSM categorical , diagnostic system, each personality disorder is thought to represent a separate, distinct category each with its own distinctive and sharply drawn boundaries that do not overlap with other categories. In categorical terms, personality disorders are like an ordinary light switch: the switch is either on, or it is off; it cannot be "somewhat on" or "somewhat off." In contrast, a dimensional approach is more like a dimmer light switch that can in fact, be "somewhat on" and "somewhat off." Pregnancy is a good example of a diagnosis where it makes good sense to think in categorical terms: one is either pregnant, or one is not. It is not possible to be "somewhat pregnant." But personality disorders do not represent conditions that are as absolute as pregnancy.
Many clinicians and researchers believe that personality disorders are best understood from a continuous or dimensional perspective (or more like a dimmer switch). The benefit of this dimensional approach can be illustrated by contrasting people who have a Narcissistic Personality Disorder with people who do not. The Narcissistic Personality Disorder is characterized by rather extreme forms of self-centeredness and grandiosity; but even ordinary, healthy people will sometimes act in ways that are self-centered and grandiose. Though the dimension of self-centeredness is the same, the difference is in the extremity of expression. People with Narcissistic Personality Disorder behave in a self-centered manner most all the time, while people without this disorder behave this way only some of the time. In this case, it makes sense to talk about a continuum or dimension of self-centeredness, which varies from low to high. Thus, we can use this dimension of self-centeredness to distinguish between people with Narcissistic Personality Disorder from those without this disorder, by plotting their degree of self-centeredness along this dimension.
While we may gain greater accuracy and precision when we view personality disorders as dimensional or continuous in nature, we loose a large degree of diagnostic simplicity. With a dimensional approach, everything becomes more complicated and open to further debate. Which dimensional model should we use? How many dimensions are important to take into account? Is it possible to establish a "cut off" on relevant dimensions beyond which we can say a particular disorder is present? For instance, just how self-centered do you need to be in order to reach the level of a Narcissistic Personality Disorder? Later in this document, we will describe a proposed dimensional model for diagnosing personality disorders to illustrate how one researcher, Otto Kernberg, has attempted to solve some of these problems. Another dimensional model has been proposed by Lorna Smith Benjamin.
1 This article was released for publication on www.mentalhelp.net in January 2011. At the time of this writing, the current diagnostic system is DSM-IV-TR (2000) but the publication of the new DSM-V is anticipated in the next few years. Further information about DSM-V is available at http://www.dsm5.org/pages/default.aspx and http://en.wikipedia.org/wiki/DSM-V.
2 It should be noted that the upcoming DSM-V may attempt to address some of the difficulties identified in this section by proposing a dimensional approach for diagnosing personality disorders. Nonetheless, an understanding of the both diagnostic methods (categorical and dimensional) is very useful because each method has its own strengths and weaknesses. Further information about DSM-V is available at http://www.dsm5.org/pages/default.aspx and http://en.wikipedia.org/wiki/DSM-V.