Characteristic patterns of thinking, feeling, and interpersonal behavior that are relatively inflexible and cause significant functional impairment or subjective distress for the individual. Individuals with personality disorders are often regarded as “difficult pts.”
Three overlapping major categories of personality disorders; pts usually present with a combination of features.
Cluster A Personality Disorders 
Includes individuals who are odd and eccentric and who maintain an emotional distance from others. The paranoid personality has pervasive mistrust and suspiciousness of others. The schizoid personality is interpersonally isolated, cold, and indifferent, while the schizotypal personality is eccentric and superstitious, with magical thinking and unusual perceptual experiences.
Cluster B Personality Disorders
Describe individuals whose behavior is impulsive, excessively emotional, and erratic. The borderline personality is impulsive and manipulative, with unpredictable and fluctuating intense moods and unstable relationships, a fear of abandonment, and occasional rage episodes. The histrionic pt is dramatic, engaging, seductive, and attention seeking. The narcissistic pt is self-centered and has an inflated sense of self-importance combined with a tendency to devalue or de-mean others, while pts with antisocial personality disorder use other people to achieve their own ends and engage in exploitative and manipulative behavior with no sense of remorse.
Cluster C Personality Disorders
Enduring traits are anxiety and fear. The dependent pt fears separation, tries to engage others to assume responsibility, and often has a help-rejecting style. Pts with obsessive-compulsive personality disorder are meticulous and perfectionistic but also inflexible and indecisive. Avoidant pts are anxious about social contact and have difficulty assuming responsibility for their isolation.