Key Facts

BPD is one of the most commonly encountered personality disorders in clinical practice. It is characterised by pervasive instability in emotions, relationships, self-image, and behaviour.

Epidemiology

General population prevalence 1-2%; up to 20% of psychiatric inpatients. In clinical settings, F:M ratio is 3:1. Mean age of presentation typically early 20s. Strong association with childhood adversity.

Aetiology

• Biosocial model (Linehan): Biological emotional vulnerability + invalidating environment → emotional dysregulation
• Childhood adversity: ~70% report abuse (sexual, physical, emotional) or neglect
• Genetic: Heritability ~40%; traits of emotional reactivity and impulsivity are heritable
• Attachment: Disorganised attachment pattern strongly associated
• Neurobiology: Amygdala hyperreactivity, reduced prefrontal cortex volume, altered serotonergic function

Pathophysiology

• Amygdala hyperactivation: Heightened emotional reactivity, threat perception
• Prefrontal cortex hypofunction: Impaired emotional regulation, impulse control
• Mentalisation deficits: Difficulty understanding own and others' mental states (Fonagy & Bateman)
• Schema activation: Early maladaptive schemas (abandonment, mistrust, defectiveness) drive interpersonal patterns

DSM-5 Criteria (≥5 of 9)

1. Frantic efforts to avoid real or imagined abandonment
2. Pattern of unstable, intense relationships (idealisation/devaluation)
3. Identity disturbance: Unstable self-image
4. Impulsivity in ≥2 areas (spending, sex, substances, reckless driving, binge eating)
5. Recurrent self-harm or suicidal behaviour
6. Affective instability: Intense, reactive mood lasting hours (rarely days)
7. Chronic feelings of emptiness
8. Inappropriate, intense anger
9. Transient stress-related paranoid ideation or dissociative symptoms

Red Flags

• Active self-harm with increasing lethality of methods
• Suicidal ideation with plan and intent
• Substance misuse escalation
• Psychotic symptoms (usually transient, stress-related)
• Severe functional decline

Bedside

• Detailed clinical assessment: Personal history, relationship patterns, trauma history
• Risk assessment: Self-harm history (methods, frequency, lethality), suicide risk, violence
• PHQ-9, GAD-7: Comorbid depression and anxiety screening
• AUDIT-C: Alcohol screening

Bloods

• TFTs: Exclude thyroid dysfunction
• FBC, LFTs: Baseline; alcohol effects
• Urine drug screen: Comorbid substance misuse

Special Tests

• ZAN-BPD: Zanarini Rating Scale for BPD — measures severity
• BSL-23: Borderline Symptom List — self-report outcome measure
• Cognitive assessment: If ADHD/ASD suspected as comorbid/differential

Non-pharmacological (NICE CG78 — first-line)

• DBT (Dialectical Behaviour Therapy): Weekly individual + group skills training (mindfulness, distress tolerance, emotion regulation, interpersonal effectiveness); 12+ months
• MBT (Mentalisation-Based Treatment): Individual + group therapy; improves reflective functioning; 18 months
• SCM (Structured Clinical Management): Case management with psychologically-informed approach
• Crisis planning: Written plan with patient, shared with GP and emergency services
• NOT recommended: Brief, unstructured psychological interventions; frequent changes of clinician

Pharmacological

• NICE CG78: Medication should NOT be used for core BPD symptoms
• Short-term only (≤1 week) for crisis:
  • Low-dose antipsychotic (quetiapine 25-100mg) or sedative antihistamine
  • Avoid benzodiazepines (dependence, disinhibition, overdose risk)
• Treat comorbid conditions (depression, anxiety) on their own merits
• Polypharmacy is a major problem — regular medication review and rationalisation

Referral Criteria

• Recurrent self-harm — specialist personality disorder service
• Need for structured psychological therapy (DBT, MBT) — secondary/tertiary care
• Crisis presentation — crisis team (avoid unnecessary admission where possible)
• Complex comorbidity — MDT approach

• Symptomatic improvement: ~85% no longer meet diagnostic criteria by age 40-50
• Functional recovery lags behind symptomatic improvement — many continue to have social/occupational difficulties
• Suicide: Lifetime rate 8-10%; highest risk in young adults in first years of treatment contact
• Self-harm: ~75% engage; ~10% ultimately die by suicide
• DBT: Reduces self-harm by ~50%, reduces hospitalisation
• MBT: Sustained improvements at 8-year follow-up
• Comorbidity: Depression (75%), substance misuse (50-70%), anxiety (50%), eating disorders (25%)

Linehan's Biosocial Model

BPD Defence Mechanisms