Do clinicians see Axis I and Axis II as different kinds of disorders?

Since 1980, personality disorders have been conceptualized as a qualitatively different kind of mental disorder and placed on their own "axis." In this study, clinicians were given 67 Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition diagnoses and were asked to discard unfamiliar diagnoses, make groups of similar diagnoses, place the most similar groups next to each other, and describe the overall structure of their taxonomies. Results showed that clinicians were more familiar with the personality disorders than with some kinds of Axis I disorders (eg, sleep disorders). Clinicians tended not to keep the personality disorders in one group, although they often kept the cluster groupings together. Cluster groupings were often placed with comorbid Axis I disorders. These data suggest that clinicians did not see the personality disorders as qualitatively different from the Axis I disorders.