Stability and change in personality disorder features: the Longitudinal Study of Personality Disorders.

BACKGROUND There exists no empirical literature documenting the long-term longitudinal stability of personality pathology comparable to that available for normal personality. A number of test-retest studies have usefully established the short-term reliability of Axis II measures. However, the test-retest design is methodologically inadequate for resolving issues related to the long-term stability of personality disorder (PD). This prospective longitudinal study evaluated the stability of PD features in multiwave perspective. METHODS Subjects (N = 250) drawn from a nonclinical university population were examined for PD features at 3 different time points using the International Personality Disorders Examination (IPDE) and the Millon Clinical Multiaxial Inventory II (MCMI-II) during a study period of 4 years. RESULTS Features of PD displayed considerable evidence of stability for individual differences and group means, at the dimensional level of analysis, on both the IPDE and the MCMI-II. Both measures revealed modest declines in PD features over time; however, the observed changes were associated with relatively small effect sizes. CONCLUSION Features of PD, viewed from a dimensional perspective, seem to be relatively stable in terms of individual differences and group means based on both clinical interview and self-administered PD assessments.