Personality disorders (PDs) are diagnoses in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), characterized by a stable, long-term pattern of behaviors and internal experiences that result in significant distress or dysfunction. PDs are diagnosed only when these experiences deviate significantly from the individual’s cultural expectations. The DSM-5 lists 10 PDs that fall into three different clusters, or groups. Cluster A (odd, eccentric) includes paranoid, schizoid, and schizotypal PDs, which are characterized by a lack of desire for close interpersonal relationships, plus odd or strange ways of thinking about the world; these PDs have genetic links with schizophrenia, especially schizotypal PD, but with less severe symptoms and better reality testing. Cluster B (dramatic, emotional, erratic) includes antisocial, borderline, histrionic, and narcissistic PDs, ...