Personality disorders are characterized by inflexible and enduring patterns of behavior and thinking that cause significant distress or impairment in social, occupational, or other important areas of functioning.

Cluster D is not a cluster of personality disorders in the DSM-5. The three clusters in the DSM-5 are Cluster A, Cluster B, and Cluster C.

Narcissistic personality disorder is characterized by a pattern of grandiosity, need for admiration, and lack of empathy.

Borderline personality disorder is characterized by a pattern of instability in relationships, self-image, and emotions.

Antisocial personality disorder is characterized by a pattern of disregard for and violation of the rights of others.

Histrionic personality disorder is characterized by a pattern of excessive emotionality and attention-seeking behavior.

Obsessive-compulsive personality disorder is the most common personality disorder, affecting approximately 2-3% of the population.

Schizoid personality disorder is the least common personality disorder, affecting approximately 1% of the population.

The average age of onset for personality disorders is early adulthood, with most cases being diagnosed between the ages of 18 and 25.

Personality disorders are thought to be caused by a combination of genetic and environmental factors.

The most effective treatment for personality disorders is a combination of medication and psychotherapy.

The prognosis for personality disorders is fair. With treatment, many people with personality disorders can improve their symptoms and live fulfilling lives.

All of the above are challenges in diagnosing personality disorders.

All of the above are challenges in treating personality disorders.

All of the above can be done to prevent personality disorders.