The Corpus Callosum

To clarify, a lot of changes are being proposed, but this post will contain a discussion of only one of the proposed changes.  That is, it has been proposed to change the way that personality disorders are established.  Currently, this is a two-step process.  The first step is to establish whether the general criteria for a personality disorder are met. 

General diagnostic criteria for a Personality Disorder

A. An enduring pattern of inner experience and behavior that deviates markedly from the expectations of the individual's culture. This pattern is manifested in two (or more) of the following areas:

    (1) cognition (i.e., ways of perceiving and interpreting self, other people, and events)
    (2) affectivity (i.e., the range, intensity, lability, and appropriateness of emotional response)
    (3) interpersonal functioning
    (4) impulse control

B. The enduring pattern is inflexible and pervasive across a broad range of personal and social situations.

C. The enduring pattern leads to clinically significant distress or impairment in social, occupational, or other important areas of functioning.

D. The pattern is stable and of long duration and its onset can be traced back at least to adolescence or early adulthood.

E. The enduring pattern is not better accounted for as a manifestation or consequence of another mental disorder.

F. The enduring pattern is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a general medical condition (e.g., head trauma).

If those criteria are met, then the second step comes into play.  The second step is a determination of the applicability of one or more of the criterion sets for a specific personality disorder.  For example, here are the criteria for Paranoid Personality Disorder:

Diagnostic criteria for 301.0 Paranoid Personality Disorder

A. A pervasive distrust and suspiciousness of others such that their motives are interpreted as malevolent, beginning by early adulthood and present in a variety of contexts, as indicated by four (or more) of the following:

    (1) suspects, without sufficient basis, that others are exploiting, harming, or deceiving him or her
    (2) is preoccupied with unjustified doubts about the loyalty or trustworthiness of friends or associates
    (3) is reluctant to confide in others because of unwarranted fear that the information will be used maliciously against him or her
    (4) reads hidden demeaning or threatening meanings into benign remarks or events
    (5) persistently bears grudges, i.e., is unforgiving of insults, injuries, or slights
    (6) perceives attacks on his or her character or reputation that are not apparent to others and is quick to react angrily or to counterattack
    (7) has recurrent suspicions, without justification, regarding fidelity of spouse or sexual partner

B. Does not occur exclusively during the course of Schizophrenia, a Mood Disorder With Psychotic Features, or another Psychotic Disorder and is not due to the direct physiological effects of a general medical condition.

Note: If criteria are met prior to the onset of Schizophrenia, add "Premorbid," e.g., "Paranoid Personality Disorder (Premorbid)."

As an aside, I often have seen students or untrained, or improperly trained, persons jump directly to the specific criterion sets, without first establishing the applicability of the general criteria.  That is a mistake.

Back to the matter at hand.  The proposed change would get rid of the criteria sets, and instead call for the use of a system that rates persons on a variety of scales.  The same scales would be used for each disorder.  This change can be conceptualized as a change from a categorical to a dimensional system.  If implemented, it would be a fundamental shift in the methodology used to diagnose personality disorders.

Unfortunately, the article I'm gong to discuss is not open access.  (I am breaking one of my rules here.)  The abstract is openly available, as is an editorial about the article.

Can Clinicians Recognize DSM-IV Personality Disorders From Five-Factor Model Descriptions of Patient Cases? (article)

The Future of Personality Disorders in DSM-V? (editorial)

Here's a snippet from the introduction to the article.  This encapsulates the crux of the issue and the proposed change:

The Diagnostic and Statistical Manual of Mental Disorders (DSM) is under revision. One proposal for the pending DSM-V is dimensionalizing personality disorders, and the Five-Factor Model (FFM) has received the most attention, either as a supplement or replacement for axis II. Whereas the DSM-IV classifies maladaptive personality with 10 discrete disorders defined by unique criteria, the FFM describes personality in a continuous manner along 30 traits grouped into five factors (Figure 1) identified as reflecting the bulk of the variance among personalities. The FFM is a promising candidate for the DSM-V because it has been shown to be biologically based, universal, temporally stable, and can avoid problems with the DSM-IV axis II categories including high comorbidity and arbitrary diagnostic thresholds.

So how would this be more useful?

The various criterion sets appear, at first glance, to describe reasonably discrete conditions.  However, in actual practice, there is considerable overlap.  The result is that many patients end up with fuzzy labels.  For example, you may see a diagnosis listed as "mixed personality disorder with histrionic and borderline features," or "Cluster B personality traits" or some such weaselly construct.  The editorial, linked above, informs us that the most common personality disorder diagnosis is "personality disorder not otherwise specified (PDNOS)."

The limitations of DSM categorical conceptualizations of personality disorders are well known: excessive co-occurrence among disorders, extreme heterogeneity among patients receiving the same diagnosis, arbitrary diagnostic thresholds for the boundaries between pathological and "normal" personality functioning, and inadequate coverage of personality psychopathology such that the diagnosis of personality disorder not otherwise specified (PDNOS) is the most common.

For a variety of purposes to which a diagnosis may be put, it is better to have a specific diagnosis.  So the current system, as currently implemented, is not working.  In part, that is a problem of implementation, not the system itself.  But part of the problem is that the categorical system often does not provide a category that really fits the patient, so there is a subjective element to the assignment to a specific category.

A dimensional system might help, by reducing the degree of subjectivity involved.  The profile of scores on the various scales would be used to assign the specific category.  If a standardized method for rating the various scales is used, it could improve some technical aspects of the diagnostic process, such as the interrater reliability.

Several dimensional models have been proposed.  The main one under study appears to be the Five-Factor Model.  This has the unfortunate acronym of FFM.  I say it is unfortunate because I can't help but think "flying fructose monster" when I see "FFM."  But that is just me.   The DSM sometimes is referred to, whimsically, as "the psychiatrist's bible," so an association to a whimsical deity is inevitable.

Personally, I have my doubts about the proposed change.  Although it has potential to be a very helpful innovation, the amount of research that would have to be done to validate this approach is very large.  In my view, it would take many years to do an adequate job.  Implementing such a fundamental change without adequate research would run the risk of making matters more confusing, not less.

To be continued.