Borderline personality disorder

Borderline personality disorder (BPD) is one of the most studied and clinically significant personality disorders. It affects approximately 1.6–5.9% of the general population and up to 20% of psychiatric inpatients. It is characterized by a pervasive pattern of instability in interpersonal relationships, self-image, affects, and impulse control.

The DSM-5 establishes 9 diagnostic criteria, of which 5 are required: frantic efforts to avoid real or imagined abandonment, unstable and intense relationships alternating between idealization and devaluation, identity disturbance, impulsivity in potentially self-damaging areas, recurrent suicidal behavior, affective instability, chronic feelings of emptiness, intense inappropriate anger, and transient paranoid ideation or dissociation.

The etiology of BPD involves a complex interaction between biological vulnerability (constitutional emotional dysregulation) and an invalidating environment during development. Linehan (1993) proposed the biosocial model: an emotionally vulnerable child raised in an environment that systematically invalidates their emotional experiences. Childhood trauma (sexual, physical, or emotional abuse) is reported in 40–70% of cases.

Treatment has undergone a revolution. Linehan's Dialectical Behavior Therapy (DBT) was the first with robust empirical evidence, focusing on mindfulness skills, distress tolerance, emotional regulation, and interpersonal effectiveness. Bateman and Fonagy's Mentalization-Based Treatment (MBT) focuses on improving the capacity to understand one's own and others' mental states.

The prognosis is more favorable than historically believed. Longitudinal studies show that most BPD patients improve significantly over time: 85% achieve symptomatic remission within 10 years, though social functioning may remain impaired. Specialized treatment significantly accelerates recovery.

It is important to distinguish BPD from other conditions sharing features (bipolar disorder, complex PTSD, ADHD). Comorbidity is very high: depression (80%), anxiety disorders (88%), substance use (65%), and eating disorders (25–50%) frequently coexist with BPD.