Big Five traits and personality disorders

There is a relationship between five factor, or "big 5," models of traits and the diagnostic approach to personality disorders, but that "the level of agreement" is derived from instruments that use these models.  The level of agreement may be a function of instrumentation, method of report, and data analysis.  In more recent years, discussion has focused on how the benefits of the highly-developed five factor model (FFM) can be blended with well-implemented personality disorder (PD) inventories, especially the DSM (American Psychiatric Association, 1994).

If diagnostic categories are limited, a more direct relationship between the two paradigms can be established; Morey (2002) did such a comparative study to attempt to correlate four diagnostic categories--borderline, schizotypal, avoidant, and obsessive-compulsive Personality--with five factor test results by comparing them to similar correlations within the community norm.  "The four personality disorder groups" "could each be distinguished from community norms" (Morey, 2002, p. 1) but differences between the groups with personality disorders were much smaller; those with personality disorders could be identified, but they could not be distinguished using the FFM trait instruments.  In other words, in their present state, Morey did not find any added benefit for using FFM instruments when assessing personality disorders.  With each of the four groups, he found neuroticism to be high, and agreeableness and conscientiousness to be low. 

Nonetheless, Morey shows that there is a relationship, albeit not specific enough for to help with personality order diagnosis.  Another relation is temporal; both PDs and traits are stable and can be shown to remain static over a period of years even when diagnosis may change, perhaps due to effective treatment (Warner, 2004).

If the diagnostic category is limited to the well-studied borderline personality disorder (BPD), then specific sub-dimensions of the five factor model are visible.  For instance, low agreeableness is shown by "self-consciousness and vulnerability in interpersonal situations" "accompanied by a hostile and suspicious approach to others" (Clarkin, Hull, Cantor, & Sanderson, 1993, p. 4).  Neuroticism from the FFM is visible as impulsiveness from the BPD criteron.

Widiger and Trull (and others) are emphatic that there is potential for crossover, or perhaps merger, between the FFM and PD diagnostic tools, specifically the DSM (2008).  They suggest that a lexical approach to diagnosis adapted from the FFM would create better classification, and hence better understanding by the community.  Better classification would help eliminate diagnostic redundancies within the existing inventories that waste clinicians' time, and the linguistic style of personality tests tends to be more acceptable to patients, and hence quicker to administer and more valuable for self-report. 

What Widiger and Trull don't mention, and perhaps should, is that the FFM is based on a long history of mathematical reasoning, and is not limited to the Lexical Hypothesis; Cattell's sources for his trait model included peer- and self-reports, and observed behaviors.  There is also a call for biological input data (Popkins, 1998).  Cattell's factor analysis equations have proved themselves, but are not yet perfected because, as presently implemented, they require subjective input at certain points (Rozalia, 2008).  This subjective input data could be replaced with data from other well-supported sources, perhaps likewise mathematically derived so as to create meta-equations, as it were, by linking existing equations as components of a bigger model.  A way to improve these equations would be to run them in reverse by inputing observed data where the results have been "out put" so as to recreate, and hence validate, input data, and in-so-doing validate the entire process.

References

American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: American Psychiatric Association.

Clarkin, J., Hull, J., Cantor, J., & Sanderson, C. (1993). Borderline personality disorder and personality traits: A comparison of SCID-II BPD and NEO-PI. Psychological Assessment, 5(4),    472-476. doi:10.1037/1040-3590.5.4.472.

Dyce, J. (1997). The big five factors of personality and their relationship to personality disorders. Journal of Clinical Psychology, 53(6), 587-593. Retrieved from Academic Search Premier database.

Morey, L. C., Gunderson, J. G., Quigley, B. D., Shea, M. T., Skodol, A. E., McGlashan, T. H., et al. (2002). The representation of borderline,
avoidant, obsessive-compulsive, and schizotypal personality disorders by the five-factor model. Journal of Personality Disorders, 16, 215–234.

Popkins, N. (1998). The five-factor model: Emergence of a taxonomic model for personality psychology. Retreived December 10, 2010 from http://www.personalityresearch.org/papers/popkins.html

Rozalia, G. (2008). Q factor analysis (Q-methodology) as data analysis technique. Annals of the University of Oradea, Economic Science Series, 17(4), 871-876. Retrieved from Business Source Complete database.

Warner, M., Morey, L., Finch, J., Gunderson, J., Skodol, A., Sanislow, C., et al. (2004). The Longitudinal Relationship of Personality Traits and Disorders. Journal of Abnormal Psychology, 113(2), 217-227. doi:10.1037/0021-843X.113.2.217.

Widiger, T., & Trull, T. (2008, January). Further Comments Toward a Dimensional Classification of Personality Disorder. American Psychologist, pp. 62-63. doi:10.1037/0003-066X.63.1.62.