Borderline Personality Disorder

Diagnosis (DSM-5)

A pervasive pattern of instability in relationships, self-image, and mood, plus impulsivity — starting by early adulthood and present across a variety of contexts. Five or more of:

1. Frantic efforts to avoid real or imagined abandonment
2. Unstable, intense interpersonal relationships, alternating between idealisation and devaluation
3. Impulsivity in at least two areas (spending, sex, substance use, reckless driving, binge eating)
4. Recurrent suicidal behaviour, gestures, threats, or self-harm
5. Affective instability — mood is highly reactive, with episodes lasting hours and rarely more than a few days
6. Chronic feelings of emptiness
7. Inappropriate, intense anger, or difficulty controlling anger
8. Transient, stress-related dissociation or paranoid ideation

Epidemiology: prevalence ~1–2%, roughly twice as common in women. Usually a family history in first-degree relatives of alcohol/substance use disorders and depression.

Clinical features

Patients are often in a near-constant state of crisis, with repetitive suicidal or self-harming acts that can serve to elicit help, express anger, or cope with overwhelming feelings. Frantic attempts to find companionship — however unsatisfactory or temporary — can lead to sexual promiscuity. Chronic emptiness and a poorly defined sense of self are common; patients may report feeling depressed “always,” despite mood clearly varying over time.

Two characteristic defence mechanisms:

• Splitting — viewing people as all good or all bad, with allegiances that frequently flip between the two.
• Projective identification — projecting unacceptable aspects of their own personality onto others, then unconsciously inducing the other person to act that part out.

BPD tends to be fairly stable over time, with a strong association with depressive episodes.

Management

Structured psychotherapy — particularly dialectical behaviour therapy (DBT) — is first-line. Medication is adjunctive only, targeting specific symptoms rather than the disorder itself:

• Useful for comorbid depression.
• Antipsychotics may help anger, hostility, or brief psychotic episodes.