borderline personality disorders

**Definition / DSM-5 criteria:** Pervasive pattern of instability in interpersonal relationships, self-image, and affect, plus marked impulsivity, beginning by early adulthood. Requires ≥5 of 9 criteria. Mnemonic "IMPULSIVITY": - Impulsivity (in ≥2 potentially self-damaging areas: spending, sex, substance use, reckless driving, binge eating) - Mood instability (affective lability; episodes last hours to a few days) - Paranoid ideation or dissociative symptoms (transient, stress-related) - Unstable self-image (identity disturbance) - Labile, intense interpersonal relationships (alternating idealization and devaluation = splitting) - Suicidal/self-mutilating behavior (recurrent) - Inappropriate, intense anger - Value of emptiness (chronic feelings of emptiness) - Impending abandonment fears (frantic efforts to avoid real or imagined abandonment)

**Epidemiology / risk factors:** - Prevalence ~1–2% in the general population; ~10% of psychiatric outpatients and ~20% of inpatients. - Diagnosed more often in women (~3:1 in clinical settings). - Strong association with childhood sexual/physical abuse, neglect, and early parental loss or separation. - Increased risk if a first-degree relative is affected (heritability ~40–50%).

**Pathophysiology:** - Gene–environment interaction. - Neuroimaging shows amygdala hyperreactivity and reduced prefrontal (orbitofrontal/anterior cingulate) regulation, which causes emotional dysregulation and impulsivity. - Serotonergic dysfunction is implicated in impulsivity and aggression. - Hypothalamic–pituitary–adrenal axis dysregulation is also described.

**Defense mechanisms (high-yield):** - Splitting is the hallmark: viewing people as all good or all bad. Example: a patient idealizes one staff member and devalues another, which can cause conflict among staff. - Others: projective identification, acting out, regression, and dissociation.

**Clinical vignette pattern:** A young woman presents after a superficial wrist-cutting episode following a breakup. She has a history of intense, stormy relationships, says she feels "empty," and shows anger outbursts. She praised her therapist at the last visit but now calls them "useless." The history shows impulsive behaviors and a pattern of fearing abandonment.

**Differential diagnosis:** - Bipolar disorder: mood episodes last days to weeks (hypomania ≥4 days, mania ≥1 week), with decreased need for sleep. BPD mood shifts are reactive to interpersonal stressors and last hours. - Histrionic PD: attention-seeking and theatrical, but without self-harm or chronic emptiness as prominent features. - Narcissistic PD: grandiosity and need for admiration, with fragile self-esteem but less self-harm. - Antisocial PD: disregard for others' rights, not primarily fear of abandonment. - MDD, PTSD, and substance use disorders are common comorbidities.

**Management:** - **First line: psychotherapy.** - Dialectical behavior therapy (DBT) has the strongest evidence. It combines CBT with mindfulness and distress tolerance, and it reduces self-harm and suicidality. - Others: mentalization-based therapy, transference-focused therapy, and schema therapy. - **Pharmacotherapy is adjunctive and symptom-targeted:** - SSRIs for depression or anxiety. - Mood stabilizers (e.g., lamotrigine, valproate) for impulsivity and affective instability. - Low-dose atypical antipsychotics for transient psychosis or paranoia. - Avoid benzodiazepines (disinhibition, dependence) and avoid polypharmacy. Overdose risk is a concern, so limit quantities. - Manage acute suicidality with safety assessment and hospitalization if needed. Chronic self-harm is not the same as intent to die, but suicide risk is real (~8–10% lifetime completed suicide).

**Course / prognosis:** Symptoms often improve with age. Many patients no longer meet criteria within 10 years, though functional impairment can persist.

**Clinical pearls for boards:** - Personality disorders are ego-syntonic, unlike many Axis I disorders, and are enduring patterns. - Cluster B = "dramatic, emotional, erratic": antisocial, borderline, histrionic, narcissistic. - Best initial answer for a borderline PD treatment question = DBT. - Set firm boundaries and use a consistent, non-judgmental team approach to manage splitting.