What Are Personality Disorder Clusters? A, B, and C Explained

You may have heard the term Cluster B personality disorders used in conversations about narcissism or difficult relationship patterns. Narcissistic personality disorder is one of the better-known diagnoses in this group, and it often gets singled out in popular discussions.

What’s less commonly explained is that narcissism is just one disorder within a broader system used by clinicians to organize personality disorders. In current diagnostic manuals, personality disorders are grouped into three clusters — A, B, and C — based on shared patterns of thinking, emotional response, and interpersonal behavior.

These clusters provide a framework for understanding how different personality disorders are related, where they overlap, and how they tend to show up in behavior and relationships.

Understanding the clusters can make the topic of personality disorders feel less abstract and more coherent, whether you are learning for personal insight, relationship understanding, or general mental health education.

Three Clusters of Personality Disorders: A, B, and C

Current editions of the Diagnostic and Statistical Manual of Mental Disorders group personality disorders into three categories—called clusters—based on shared traits.

Each cluster includes different disorders that have certain characteristics in common, but also have their own defining traits.

Cluster A: Odd/Eccentric

• Paranoid Personality Disorder
• Schizoid Personality Disorder
• Schizotypal Personality Disorder

Cluster B: Dramatic/Emotional/Erratic

• Antisocial Personality Disorder
• Borderline Personality Disorder
• Histrionic Personality Disorder
• Narcissistic Personality Disorder

Cluster C: Anxious/Fearful

• Avoidant Personality Disorder
• Dependent Personality Disorder
• Obsessive-Compulsive Personality Disorder (not the same as OCD)

Key Characteristics of 10 Personality Disorders By Cluster

Now that you know how the 10 official personality disorders are grouped into three clusters, let’s take a closer look at each disorder and some of the traits that define them.

Cluster A: Odd or Eccentric

Cluster A includes people who tend to appear socially awkward, emotionally distant, or unconventional in behavior or thinking. Others may see them as unusual or hard to connect with.

Paranoid
Distrust of others, suspicion without evidence, hypersensitivity to perceived threats or slights, persistent belief that others are out to harm or deceive them

Schizoid
Emotional detachment, social withdrawal, little interest in relationships, indifferent to praise or criticism, limited emotional expression

Schizotypal
Eccentric behavior, odd beliefs or magical thinking, social anxiety, suspiciousness, vague or unusual speech, discomfort with close relationships

Cluster B: Dramatic, Emotional, or Erratic

This group is known for intense emotions, impulsivity, and unstable relationships. People in this cluster often struggle with self-regulation and may create turmoil in their personal or professional lives.

Antisocial
Disregard for others’ rights, deceitfulness, impulsivity, aggression, lack of remorse, history of rule-breaking or criminal behavior.

Borderline
Emotional instability, intense fear of abandonment, unstable self-image, impulsive behavior, self-harm or suicidal gestures, turbulent relationships

Histrionic
Attention-seeking, dramatic or theatrical behavior, shallow emotions, strong need for approval, suggestibility, inappropriate seductiveness

Narcissistic
Inflated sense of self-importance, need for admiration, lack of empathy, entitlement, exaggeration of achievements, sensitivity to criticism

Cluster C: Anxious or Fearful

Cluster C includes people who are overly worried about criticism, rejection, or losing control. Their behaviors are often driven by fear or insecurity.

Avoidant
Social inhibition, fear of rejection or criticism, low self-esteem, avoidance of new activities, strong desire for connection but fear of exposure

Dependent
Excessive need to be cared for, submissiveness, difficulty making decisions independently, fear of separation, difficulty expressing disagreement

Obsessive-Compulsive
Preoccupation with order, perfectionism, control, inflexibility, over-focus on rules and details, reluctance to delegate, rigidity in thinking

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