Personality disorders (PDs) are enduring and pervasive patterns of inner functioning and behavior that markedly deviate from the expectations of the individual's culture. They affect cognition, affectivity, interpersonal functioning, and impulse control. They are stable over time, inflexible, and generate significant distress or functional impairment.
The DSM-5 (APA, 2013) classifies 10 personality disorders into three clusters. Cluster A ('odd/eccentric') includes paranoid, schizoid, and schizotypal PDs. Cluster B ('dramatic/emotional') includes antisocial, borderline, histrionic, and narcissistic PDs. Cluster C ('anxious/fearful') includes avoidant, dependent, and obsessive-compulsive PDs.
The ICD-11 (WHO, 2022) has adopted an alternative dimensional approach, replacing discrete categories with a single 'personality disorder' diagnosis with severity specifiers (mild, moderate, severe) and prominent traits (negative affectivity, detachment, dissociality, disinhibition, anankastia). This reflects research showing that PDs rarely appear in pure forms.
The prevalence of PDs in the general population is estimated at 6–15%. They are more common in clinical populations, where they affect 40–60% of outpatient mental health patients. Comorbidity between PDs and with other mental disorders is the rule rather than the exception.
Etiology is multifactorial: genetic factors (heritability of 40–60%), adverse childhood experiences (trauma, neglect, insecure attachment), and gene-environment interactions. There is no single causal factor, but complex developmental pathways that converge in the characteristic rigidity of PDs.
Treatment has evolved significantly. Historically considered untreatable, several psychotherapeutic approaches have demonstrated efficacy: Dialectical Behavior Therapy (DBT) for borderline PD, Mentalization-Based Treatment (MBT), Schema Therapy, and Transference-Focused Psychotherapy (TFP). Pharmacotherapy is complementary, not curative.