Borderline personality disorder (BPD) is controversial and difficult to diagnose due to its similarities with other disorders and lack of clear definition. Some believe it is a manifestation of post-traumatic stress disorder. Linehan theorizes that those with BPD are biologically predisposed to react strongly to stress and take longer to recover. They also often experienced childhood trauma. BPD is characterized by instability in mood, behavior, and relationships as well as a fear of abandonment. Effective treatment options include dialectical behavior therapy and medications to manage symptoms.