Defense mechanisms associated with borderline personality disorder.

This study assessed the defensive functioning of 290 criteria-defined borderline patients and compared it to that of 72 patients with other forms of axis II psychopathology. The Defense Style Questionnaire (DSQ), a self-report measure with demonstrated criterion validity and internal consistency, was administered to 362 axis II inpatients diagnosed using semistructured interviews of proven reliability. Borderline patients had significantly higher scores than axis II comparison subjects on three of the four defense styles assessed by the DSQ: self-sacrificing, maladaptive action, and image-distorting defenses. They also had significantly higher scores than axis II comparison subjects on eight of the 19 defense mechanisms studied. More specifically, borderline patients had significantly higher scores on one neurotic-level defense (undoing), four immature defenses (acting out, emotional hypochondriasis, passive aggression, and projection), and two image-distorting/borderline defenses (projective identification and splitting). In contrast, axis II comparison subjects had a significantly higher score than borderline patients on one mature defense (suppression). When all significant defenses were considered together, three were found to be significant predictors of a borderline diagnosis: acting out, emotional hypochondriasis, and undoing. This model has both good sensitivity (.95) and positive predictive power (.86). Taken together, the results of this study suggest that the defensive profile of borderline patients is distinct from that of patients with other forms of axis II pathology. They also suggest that the defensive triad of acting out, emotional hypochondriasis, and undoing may serve as a useful clinical marker for the borderline diagnosis, particularly in settings where the base rate of the disorder is high.