Which Cluster B personality disorder is most commonly associated with a pattern of unstable interpersonal relationships, identity disturbance, impulsive behaviors, and recurrent suicidal ideation or self-harm?

Explanation

## Borderline Personality Disorder (BPD) **Key Point:** BPD is a Cluster B personality disorder characterized by instability across four domains: relationships, self-image, affect, and behavior. It is the most common personality disorder in clinical settings and carries significant suicide risk. ### Diagnostic Criteria (DSM-5) — At least 5 of 9 1. Frantic efforts to avoid real or imagined abandonment 2. Unstable and intense interpersonal relationships (idealization → devaluation) 3. Unstable self-image or sense of self 4. Recurrent self-harm, suicidal behavior, threats, or gestures 5. Affective instability due to marked reactivity of mood 6. Chronic feelings of emptiness 7. Inappropriate, intense anger or difficulty controlling anger 8. Transient, stress-related paranoid ideation or severe dissociation 9. Impulsive behaviors in at least 2 areas that are potentially self-damaging ### Cluster B Personality Disorders Comparison | Disorder | Core Theme | Relationship Pattern | Impulsivity | |----------|-----------|----------------------|-------------| | **Borderline** | Instability & abandonment fear | Intense, unstable | High; self-harm | | Antisocial | Disregard for rights | Manipulative, callous | High; harm others | | Histrionic | Attention-seeking | Shallow, theatrical | Moderate; for attention | | Narcissistic | Grandiosity & admiration | Exploitative | Low; controlled | **High-Yield:** BPD ≠ Dissociative Identity Disorder (DID). BPD has unstable self-image; DID has distinct alters. BPD is the most common PD in psychiatric inpatients and has the highest suicide completion rate among PDs (8–10%). **Mnemonic:** **ABCDEF** for BPD features: - **A**bandonment fears - **B**lack-and-white thinking (splitting) - **C**hronic emptiness - **D**issociation (transient) - **E**motional instability - **F**urious anger + self-harm **Clinical Pearl:** Patients often have a history of childhood trauma, invalidating environments, or early loss. Dialectical Behavior Therapy (DBT) is the gold-standard psychotherapy.