Seven-Year Course of Borderline Personality Disorder Features: Borderline Pathology Is as Unstable as Depression...

Borderline personality disorder (PD) historically is construed as an unremitting condition with poor prognosis. The present study takes a new approach to examining stability and change in borderline PD by explaining symptom expression in terms of an unchanging foundation-termed borderline proneness-on one hand, and transitory influences on the other. We monitored borderline PD symptoms annually in a large sample of high-risk adolescent girls (N = 2,450) from ages 14 to 20. Trait-state-occasion modeling revealed that just over half (52-57%) of borderline PD symptom variation was attributable to fixed borderline proneness, whereas the remainder was subject to change across yearly measurement occasions. This degree of stability was no larger than the corresponding estimate for depression, a condition known for its variable course. Our results indicate that, contrary to its reputation, borderline pathology is not set in stone, and it fluctuates in response to situational influences.