there seems to be a lot of disagreement regarding the use and usefulness of the DSM-IV. many recognize its inherent limitations while others refer to it as the Bible of the APA and seek its guidance as if the whole body of knowledge in the field of psychology is contained therein. its stated purpose is to facilitate consistent communication within the psychological community, which translates to applying labels precisely. it contains disclaimers that attempt to soften the inherently hard edges with respect to its pass/fail criteria. the concept of comorbidity seems archaic [in my opinion] when talking about overlapping cluster B diagnoses, often so closely related as to be virtually indistinguishable, as if they were completely separate issues. disordered personalities do not present in tidy packages ready to be barcoded, scanned, labeled and arranged in neat rows without so much as a thought toward etiology, biology or the uniqueness of each individual. DSM-IV is a rather simple checklist that seeks to establish uniform semantics in the highly imprecise and evolving field of psychology with the same degree of measurable precision that has benefited physical medicine and the other pure sciences. It relies on observable behavior to the exclusion of all other knowledge and experience, because practically speaking that is the only universally available input in the context of the clinical interview. the irony is that in practice, especially at the edges of differential diagnoses, its application is almost entirely subjective based on the astuteness, predisposition and judgement of the individual practitioner. Whether or not a particular behavior is observable to the degree of deserving a checkmark today is always a yes/no judgement. tomorrow, next door, or with two more cups of coffee the judgement might go the other way.
interestingly enough, Theodore Millon (Personality Disorders in Modern Life, and many more), preeminent authority on personality disorder, was instrumental in the development the DSM-IV. criteria is decided by committee, using logical and practical considerations as well as compromise, to facilitate consistent application, and defaulting to non-diagnosis (effectively indicating that existing observable behaviors don't exist) when some degree of doubt is present as to whether an individual meets the full criteria, both in quantity and severity.
I am posting Kernberg's chart (for about the 5th time) which takes into account the relatedness and variability within the realm of cluster B disorders. Kernberg believes that borderline personality organization underlies the entire spectrum. severity of neurosis/psychosis is graphed on the y axis and introversion/extroversion on the x axis. these factors coincide with certain expressions (diagnoses) within the realm of cluster B disorders, or borderline personality organization. I assume that characteristics would typically occupy ameba-shaped, irregular areas on the chart, large or small, and that some individuals might occupy discrete areas on the chart.
http://salparadise.net/images/kernbergrelations_480.jpgI am not implying that this chart is the perfect model, just that it seems more representative than a checklist and describes the relativity of the diagnoses to one another as well as presenting a different point of view regarding borderline organization and cluster B disorders.