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Personality disorders—atypical ways of thinking about oneself and relating to other people—are grouped into three clusters: A, B, and C. Cluster B disorders are marked by inappropriate, volatile emotionality and often unpredictable behavior. The disorders in Cluster B are antisocial personality disorder, borderline personality disorder, histrionic personality disorder, and narcissistic personality disorder.

Understanding the Cluster B Disorders

Cluster B disorders are taxonomically grouped together by the DSM-V because a single, clear-cut diagnosis is very rare, and patients often exhibit a number of overlapping symptoms. For example, someone with borderline tendencies (such as intense mood swings) may present with histrionic symptom overlap (for example, behaving erratically to garner attention). Similarly, someone who exhibits signs of both narcissistic personality disorder and antisocial personality disorder is sometimes referred to as a “malignant narcissist.”

What are examples of Cluster B disorders?

There are four personality disorders within Cluster B. They include antisocial personality disorder, borderline personality disorder, histrionic personality disorder, and narcissistic personality disorder. Though the disorders can occur alone, symptoms and diagnoses can overlap, either within one cluster or across several.

What is antisocial personality disorder?

Antisocial personality disorder describes a pattern of behavior in which an individual regularly violates the physical or emotional rights of others; behaves recklessly, violently, or deceitfully; and lacks remorse for any harm caused to others. Its estimated prevalence rate is between 0.2 and 3.3 percent.

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Cluster B vs. Other Personality Disorders
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All personality disorders are deeply ingrained, rigid ways of behaving and thinking that can greatly affect the individual’s relationships and mental well-being. There is wide variety in the symptomatology and interpersonal challenges caused by personality disorders; based on similarities between certain disorders and a greater possibility for overlap, the 10 disorders currently in the category are divided into three clusters: A, B, and C.

Though Cluster B disorders draw significant attention because they are frequently portrayed in the media—and because those with the disorders often wreak havoc in their personal relationships—they are the least common personality disorders, according to DSM estimates. They are characterized by dramatic, manipulative, or emotional behaviors. Cluster A is characterized by odd or erratic behaviors, while Cluster C disorders are characterized by anxious or fearful behaviors. Within clusters, there is significant overlap between the disorders; overlap can occur across clusters as well.

How common are Cluster B disorders?

Cluster B disorders have a combined estimated prevalence rate of 1.5 percent, according to DSM estimates. 

What causes Cluster B disorders?

The causes of Cluster B disorders are not well-understood. For each, genetics, early life experiences, and environmental influences are thought to play a role. Genetics are strongly implicated in antisocial personality disorder and borderline personality disorder; having a close relative with either disorder greatly increases one’s likelihood of developing it. 

How Cluster B Disorders Are Treated

Though medication and certain therapy approaches have shown some promise, on the whole, Cluster B and all other personality disorders are difficult to treat. As such, they can continue to engender impairment for the individual and pain for those within the afflicted person’s orbit even after treatment is initiated.

Treatment is complicated by the fact that many people with personality disorders do not seek professional help, and may not feel as if anything is wrong with them; those with narcissistic personality disorder and antisocial personality disorder, in particular, may not seek help unless requested by a family member or ordered by the legal system.

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Can Cluster B disorders be cured?

Personality disorders, by definition, are chronic maladaptive patterns of behavior. While improvement is possible and some overt symptoms do appear to go into “remission” after treatment, in most cases, the individual will likely continue to struggle with behavioral symptoms and/or internal distress for the remainder of their lives.

What is the best treatment for borderline personality disorder?

BPD is typically treated with dialectical behavioral therapy (DBT), mentalization-based therapy (MBT), cognitive behavioral therapy (CBT), or psychodynamic psychotherapy. Some studies have suggested that DBT may be the most effective, but general psychotherapy and psychodynamic approaches have also shown promise.

How to Deal with a Volatile Individual

Dealing with someone who has a Cluster B disorder can be very difficult. But it's important to remember that while no one chooses to have a personality disorder, individuals can choose how they respond to Cluster B behaviors.

If forced to deal with an individual with a Cluster B disorder on a regular basis (because they are a coworker, family member, or partner), it’s more effective to modify your own behavior and emotional responses; trying to force or persuade the individual to behave differently will likely be ineffective and may increase hostility and frustration. Regardless of how one responds when confronted with a Cluster B personality, it’s wise to avoid the urge to diagnose someone outside of a formal clinical setting.

What is the best way to respond to someone with a Cluster B disorder?

Though it may be difficult, it’s often helpful to attempt to cultivate compassion for the sufferer. Other available options include distance (set boundaries), delay (deferring until the person calms down), and deny (say as little as possible; focus on external demands).

How can you tell if someone is a narcissist?

Key signs of narcissism include self-enhancement, a sense of entitlement, lack of awareness (or concern) about the effects of their behavior, and a strong need for approval or attention from others. Narcissists tend to blame others for their failings and have fragile self-esteem, becoming defensive or aggressive when challenged.

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