So far, we have reviewed the Type B personality disorders related to impulsive, dramatic, emotional, or erratic behavior. Now we’ll take a closer look at borderline personality disorder (BPD).

Borderline Personality Disorder

Borderline personality disorder (BPD) is a mental illness characterized by a long-term pattern of unstable relationships, distorted sense of self, and strong emotional reactions. Those affected often engage in self-harm and other dangerous behavior. They may also struggle with a feeling of emptiness, fear of abandonment, and detachment from reality.

Figure 1. Those with borderline personality disorder may quickly change their mood or behavior.

The DSM-5 diagnostic criteria for borderline personality disorder is

A. A pervasive pattern of instability of interpersonal relationships, self-image, and affects as well as marked impulsivity beginning by early adulthood and present in a variety of contexts as indicated by five or more of the following:

1. Intense fear of abandonment. This may lead to frantic efforts to keep people from leaving or pulling away, even if the fear isn’t based in reality.
2. Unstable and intense relationships. A person may swing between idealizing others (seeing them as perfect) and devaluing them (seeing them as cruel or uncaring), often in a short span of time.
3. Unclear or shifting sense of self. The person may struggle to define who they are or what they value, and their goals, opinions, or identity may change frequently.
4. Risky or impulsive behaviors. These might include reckless spending, risky sex, substance use, binge eating, or unsafe driving. These behaviors are typically aimed at managing emotions but can cause serious harm.
5. Self-harming or suicidal behavior. Many people with BPD experience thoughts of suicide or engage in self-injury, such as cutting or burning, especially during emotional crises. This criteria is its own separate criterion, not to be double-counted in impulsivity or fear of abandonment.
6. Extreme emotional reactivity. Moods may shift rapidly — for example, going from feeling okay to deeply sad or angry — often in response to interpersonal stress. These mood changes usually last for hours or a day, not weeks.
7. Chronic feelings of emptiness. Some people with BPD describe feeling “hollow” or like they don’t exist, even when life seems to be going well.
8. Explosive or inappropriate anger. This can include frequent temper outbursts, sarcasm, bitterness, or physical fights that are hard to control or out of proportion to the situation.
9. Paranoia or disconnection from reality. Under stress, a person might feel suspicious of others, disconnected from their surroundings, or unsure of what’s real (a symptom known as dissociation).

Differential Diagnosis

When considering a diagnosis of borderline personality disorder, the differential diagnosis should always include other personality disorders since overlap is common, especially within Cluster B. Other diagnostic considerations include

• substance use disorder
• non-suicidal self-injury disorder (a time-limited phenomenon in many patients)
• bipolar disorder (five times less prevalent, but comorbidity approaches 15%)
• autism spectrum disorder (patients with congenital deficits in theory of mind may also show severe mood dysregulation)

Epidemiology

The behavior in BPD typically begins by early adulthood and occurs across a variety of situations. Substance abuse, depression, and eating disorders are commonly associated with BPD. Approximately 10% of people affected with the disorder commit suicide. There is a genetic predisposition for the disorder. Twin studies show over 50% heritability (greater than that for major depression). Twin studies performed in 2000 and 2008 both demonstrated higher concordance of the rate of borderline personality disorder for monozygotic versus dizygotic twins. Environmental factors that have been identified as contributing to the development of borderline personality disorder include primarily childhood maltreatment (physical, sexual, or neglect), found in up to 70% of people with BPD, as well as maternal separation, poor maternal attachment, inappropriate family boundaries, parental substance abuse, and serious parental psychopathology.

Approximately 1.6% of people have BPD in a given year, with some estimates as high as 6%. Women are diagnosed about three times as often as men. The disorder appears to become less common among older people. Up to half of those with BPD improve over a 10-year period.

Etiology

The causes of BPD are unclear but seem to involve genetic, environmental, and social factors. It occurs about five times more often in a person who has an affected close relative. Adverse life events appear to also play a role.

As is the case with other mental disorders, the causes of BPD are complex and not fully agreed upon. Evidence suggests that BPD and PTSD may be related in some way. Most researchers agree that a history of childhood trauma can be a contributing factor.

Comorbidity

Patients with borderline personality disorder have been shown to have high rates of comorbid disorders:

• mood disorders: 80% to 96%
  

  Figure 2. BPD can exist simultaneously with other disorders in a patient.

• anxiety disorders: 88%
• substance abuse disorders: 64%
• eating disorders: 53%
• attention deficit hyperactivity disorder (ADHD): 10–30%
• bipolar disorder: 15%
• somatoform disorders: 10%

Treatment

Treatment of borderline personality disorder relies on psychotherapy. Three evidence-based therapies are effective for patients with borderline personality disorder. First, mentalizing-based therapy (MBT) helps patients manage emotion dysregulation by feeling understood, allowing them to be more curious and make fewer assumptions about the intentions of the people around them. A second therapy, dialectical behavior therapy (DBT) combines mindfulness practices with concrete interpersonal and emotion regulation skills. Third, transference-focused psychotherapy (TFP) focuses on using the patient–therapist relationship to develop the patient’s awareness of problematic interpersonal dynamics. MBT and DBT each incorporate individual and group treatment over 12 to 18 months. For adolescents, family therapy may be an appropriate substitute for group therapy, though not always.