Personality Disorder

Personality disorders are enduring, inflexible patterns of inner experience and behavior that deviate markedly from cultural expectations, are pervasive across contexts, begin in adolescence or early adulthood, and cause significant distress or functional impairment. The DSM-5-TR classifies personality disorders into three clusters based on shared phenomenology: Cluster A (odd/eccentric — paranoid, schizoid, schizotypal), Cluster B (dramatic/erratic — antisocial, borderline, histrionic, narcissistic), and Cluster C (anxious/fearful — avoidant, dependent, obsessive-compulsive). Borderline personality disorder (BPD) has the most robust neurobiological evidence: reduced prefrontal cortex volume and function (impaired emotion regulation), hyperactive amygdala (emotional hyperreactivity), and disrupted serotonergic and dopaminergic neurotransmission. Dialectical behavior therapy (DBT) is the gold standard psychotherapy for BPD, targeting the core skills deficits of mindfulness, distress tolerance, emotion regulation, and interpersonal effectiveness.