Why are personality disorders difficult to characterize and treat?

Because individuals with personality disorders typically express their discomfort in the form of anxiety, depressive symptoms, anger or impulse control, there is often a high degree of comorbidity with other mental health diagnoses as well as among two or more of the personality disorders. 

There are, however, structured diagnostic interviews that can be very helpful in obtaining diagnostic clarity. As such, personality disorders are not very difficult to characterize, but how much to attribute to the various symptoms of distress—such as panic or depression—as separate, co-existing, or caused by personality disorder, can be very difficult.

How might redefining diagnostic criteria of personality disorders improve treatment?

I believe that redefining the diagnostic criteria may increase the reliability of a diagnosis, improve communication between professionals, and ultimately improve the methods of clinical research studies regarding the development of effective treatments. However, it is my opinion that modifying the diagnostic criteria alone will not improve treatment.

The proposed diagnostic system is said to be simpler than the existing one. Instead of the current 10 personality types, the DSM-V (fifth edition of the Diagnostic and Statistical Manual) has simplified the system by cutting them down to just five. Also, clinicians will have a paragraph-length description of each type and rate on a 1 to 5 scale how much a patient matches each one (with 4 or 5 being a threshold for diagnosis). There are research studies that have found that clinicians tend to find this the most useful and comprehensive method for personality diagnosis, improving clinical description and treatment planning from the current system.

Another element of the newly proposed system involves the clinician determining diagnostic information based upon six personality “trait domains” derived from many years of research concerning a widely used five-factor model of personality. While there is significant personality research on these factors, their greatest limitation is the sense they are too vague for clinical use.  To compare, it would be like rating someone's level of usual sadness, as opposed to having a coherent syndrome of depression.

You say the proposed diagnostic system is said to be simpler than the existing one. Some experts oppose this move, claiming that it is “premature and reckless” to throw out existing definitions and that the diagnoses can’t be simplified so much. Do you agree with this criticism or do you think that it’s necessary to start over?

Neither. While there is legitimate criticism of the new diagnostic system, if it can improve evaluation, increase reliability of diagnoses, and improve methods of clinical research, then it may be useful. It is my sense that it is unrealistic to expect improved treatment from some increased clarity of diagnoses.

As a practicing clinician, it seems important to me to embrace the viewpoint that a diagnosis of personality disorder is a helpful description of the problems that someone is experiencing, and a reliable way for professionals to communicate, not a prescription for treatment. Enduring personality characteristics represent a complex interaction of one’s genetics, temperament, early learning experiences, emotional reactivity and psychological coping skills. When that is combined with the importance of understanding an individual’s current social, cultural, spiritual and physical environment, it is more useful for a clinician to develop an individualized case formulation or “life story.”  I believe that this is the most effective way to improve treatment and help a person to change his or her life for the better.

For this reason, I place less emphasis on the diagnostic system and greater emphasis on the application of my knowledge to an understanding of the causal mechanisms that contribute to a person’s suffering and the scientific evidence base of the psychotherapies that have been developed to improve specific target areas of their lives.