Are the interpersonal and identity disturbances in the borderline personality disorder criteria linked to the traits of affective instability and impulsivity?

This study examines the degree to which two putative biologically influenced personality traits, affective instability and impulsive aggression, are associated with some of the interpersonal and intrapsychic disturbances of borderline personality disorder (BPD) and with choice of defense mechanism. In a sample of 152 personality disorder patients, affective instability and impulsive aggression were measured. Defense mechanisms were assessed in 140 of these patients using the Defensive Style Questionnaire (DSQ). The correlations between the traits of affective instability and impulsive aggression and the eight DSM-III-R criteria for borderline personality disorder and 20 DSQ defenses were examined. Affective instability was significantly correlated with the DSM-III-R criteria of identity disturbance, chronic emptiness or boredom, inappropriate anger, suicidality, and the affective instability criteria. It also was associated with the defenses of splitting, projection, acting out, passive aggression, undoing, and autistic fantasy. Impulsive aggression was related to unstable interpersonal relationships, inappropriate anger and impulsiveness and with the defense of acting out. It was negatively correlated with the defenses of suppression and reaction formation. A number of the interpersonal and experiential disturbances and defense mechanisms that are features of BPD are associated with the traits of affective instability and impulsive aggression among patients with personality disorders.