Borderline personality disorder is a psychological disorder with a characteristic pervasive pattern of instability in affect regulation, impulse control, interpersonal relationships, and self-image.¹ Patients with borderline personality disorder are often characterized as difficult because of aggressive outbursts, health-sabotaging behaviors (i.e., exercising on an injury), and high health care utilization.^2,3

Borderline personality disorder has a prevalence of 1.6% in the general population.⁴ In one study, it was found to be present in 6.4% of adult primary care visits, about fourfold higher than what has been noted in general community studies.^4–6 Psychiatric diagnostic comorbidities are common. According to one epidemiologic survey, 85% of patients with borderline personality disorder had at least one comorbid psychiatric disorder.⁷ There is an established correlation between increased suicide risk and a diagnosis of borderline personality disorder.⁸

Etiology and Pathogenesis

Borderline personality disorder is thought to be caused by a combination of genetic, neurobiologic, and psychosocial factors, with moderate evidence for genetic transmission and heritability, combined with environmental factors such as trauma.¹ Trauma and neglect may exacerbate biologic predisposition and behavioral tendencies already present in those with borderline personality disorder.⁹ Nearly one-third of patients with borderline personality disorder have been raped or sexually assaulted during adulthood.⁸

In a study of Hispanic patients in primary care, childhood and adulthood interpersonally traumatic events were strongly associated with borderline personality disorder.¹⁰ Increased awareness of the prevalence of the disorder among underrepresented ethnic minorities receiving primary care, in addition to the high rates of trauma exposure in this population, may enhance physicians' ability to detect borderline personality disorder in these patients and provide appropriate referrals.¹⁰

Clinical Presentation

HALLMARK SYMPTOMS

The core features of borderline personality disorder are instability of interpersonal relationships, negative self-image, and marked impulsivity, especially in expressing emotions, controlling moods, and exhibiting chronic suicidal tendencies.^1,11 Borderline personality disorder can also present as multiple vague somatic complaints, high-risk sexual behaviors, binge eating, or chronic pain.⁵ Patients commonly engage in splitting, which is when relationships are rapidly devalued or over-valued (e.g., in one moment the patient can highly appreciate a clinician and then reverse this opinion when an appointment needs to be rescheduled or another perceived rejection occurs).⁶ A useful model organizes the disorder into three dimensions that are outlined in Table 1.^11,12

Although longstanding beliefs suggest borderline personality disorder has a chronic unchanging course over a patient's lifespan, most patients will experience remission.^6,13 Predictors of good outcomes include factors related to self-efficacy and a favorable psychosocial history, whereas predictors of poor outcomes include greater severity and chronicity of illness, higher degrees of comorbidity, and a history of childhood adversity.¹³ Despite high rates of remission over time, global functioning may not improve, with up to 75% of patients who have borderline personality disorder lacking full-time employment, even during remission.^6,11

DIAGNOSTIC CRITERIA

Table 2 lists the diagnostic criteria for borderline personality disorder as outlined in the Diagnostic and Statistical Manual of Mental Disorders, 5th ed. (DSM-5).¹⁴ The clinical diagnosis is based on a comprehensive psychiatric assessment that gathers information from multiple sources, including a self-reported clinical history, clinician observations, review of the patient's medical record, and information from the patient's friends and family. The McLean Screening Instrument for Borderline Personality Disorder is a self-report measure that screens patients for the disorder, but it is not intended to make a diagnosis.¹⁵ Borderline personality disorder is chronically underdiagnosed in clinical populations, and use of structured interviews is encouraged to improve assessment.¹⁶ Interview assessments that are designed specifically for borderline personality disorder include the Revised Diagnostic Interview for Borderlines and the Structured Clinical Interview for the DSM-5 Alternative Model for Personality Disorders.^17,18