- Key People:
- Karen Horney
- Patrick McGorry
- On the Web:
- Idaho Pressbooks Network - Introduction to Psychological Disorders - Personality Disorders (Oct. 16, 2026)
personality disorder
What are personality disorders?
How are personality disorders classified?
What role do genetic and environmental factors play in personality disorders?
How are personality disorders treated?
personality disorder, any of a group of mental disorders characterized by enduring patterns of cognition, emotional experience, and interpersonal functioning that differ markedly from cultural expectations and that impair an individualâs relationships, work, or other important areas of functioning.
Although everyone possesses personality traits that are more or less stable, with some variation over time, personality disorders are diagnosed when those traits become inflexible, pervasive, and maladaptive across many situations. These patterns typically emerge during adolescence or early adulthood and remain relatively stable over time, though their severity and expression may change throughout life. Individuals with personality disorders may have difficulty recognizing that their patterns of behavior contribute to interpersonal or occupational problems, and many seek treatment only after experiencing significant distress or because of associated conditions such as anxiety, depression, or substance use disorders.
Types of personality disorders
Personality disorders are commonly grouped into three clusters based on shared patterns of thought, emotional response, and action, although individual disorders remain distinct and symptoms may overlap.
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Cluster A
Cluster A disorders are characterized by unusual or eccentric patterns of behavior and difficulties in forming close relationships. They include paranoid personality disorder, in which individuals are suspicious of and have difficulty trusting others; schizoid personality disorder, marked by emotional detachment and limited interest in social relationships; and schizotypal personality disorder, which involves social discomfort, unusual beliefs or perceptions, and eccentric actions and ways of interacting with others.
Cluster B
Cluster B disorders are associated with dramatic, emotional, or erratic behavior. They include antisocial personality disorder, characterized by persistent disregard for the rights of others; borderline personality disorder, which involves a combination of impulsive tendencies and instability in emotions, relationships, and self-image; histrionic personality disorder, in which excessive emotionality and attention-seeking behavior are prominent; and narcissistic personality disorder, in which thoughts and actions are dominated by an exaggerated sense of self-importance, a need for admiration, and reduced empathy for others.
Cluster C
Cluster C disorders are characterized by anxious or fearful perceptions and responses to the world. These include avoidant personality disorder, involving extreme sensitivity to criticism and social inhibition despite a desire for close relationships; dependent personality disorder, marked by an excessive need for reassurance and care from others; and obsessive-compulsive personality disorder, characterized by a preoccupation with orderliness, perfectionism, and control that differs from the intrusive thoughts and repetitive actions of obsessive-compulsive disorder (OCD).
Causes and treatment
The causes of personality disorders are not fully understood. Evidence suggests that they arise through complex interactions among genetic factors, temperament, brain development, and environmental influences. Adverse childhood experiencesâincluding neglect, abuse, trauma, inconsistent caregiving, and chronic family conflictâhave been associated with an increased risk for some personality disorders, although many individuals exposed to such experiences do not develop these conditions. Likewise, inherited traits may increase susceptibility, but no single genetic or environmental factor is sufficient to explain their development.
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Treatment often focuses on helping individuals recognize maladaptive patterns, improve interpersonal functioning, and develop more effective coping strategies rather than fundamentally altering personality itself. Psychotherapy is the primary treatment for most personality disorders. Approaches such as cognitive behavior therapy (CBT), dialectical behavior therapy (DBT), psychodynamic psychotherapy, schema therapy, and mentalization-based therapy have demonstrated benefit for particular disorders and symptoms. Medication does not treat personality disorders directly but may be used to relieve associated conditions or symptoms, such as anxiety, depression, mood instability, or impulsivity. Although treatment may require months or years, many individuals experience significant improvement in symptoms, relationships, and overall functioning.