Should an axis for defense mechanisms be included in DSM-IV?

The purpose of this review is to address empirical evidence bearing on the desirability of including a Defense Mechanisms Axis in DSM-IV. The authors reviewed studies based on standardized clinical or self-report methods for assessing defense mechanisms. Information was sought pertinent to methods for assessment, relevance to clinicians with diverse theoretical perspectives, definitions, suitability for an axial format, complexity, reliability, clinical utility, and relationship to existing axes. Methods for reliably rating defense mechanisms have been developed, and data on the clinical utility of ratings have begun to accumulate. A consensus on definitions is emerging, and evidence supports a hierarchy of defenses based on their adaptiveness. Since training in psychodynamic theory and treatment approaches is required of residencies performed in the United States, all psychiatrists should be able to evaluate patient defenses. However, new methodologies have not been tested under usual clinical conditions with limited, "live" clinical data. A viable option for DSM-IV is the inclusion of a defense mechanisms axis in an appendix of optional axes for use in special clinical and research settings. In addition to providing dynamically meaningful diagnostic data, this axis would facilitate expansion of the empirical data base on a standardized measure of defenses under conditions of routine clinical practice.