mental disorder

Introduction
Types and causes of mental disorders
- Classification and epidemiology
  - Classification
    - Psychoses
    - Neuroses
  - Epidemiology
- Theories of causation
  - Organic and hereditary etiologies
    - Genetics
    - Biochemistry
    - Neuropathology
  - Psychodynamic etiologies
    - Theories of personality development
    - Non-Freudian psychodynamics
  - Behavioral etiology
- Major diagnostic categories
  - Organic mental disorders
    - Senile and presenile dementia
    - Other organic syndromes
  - Substance use disorders
  - Schizophrenia
    - Clinical features
    - Course and prognosis
    - Etiology
    - Treatment
  - Mood disorders
    - Major mood disorders
    - Other mood disorders
  - Anxiety disorders
  - Somatoform disorders
    - Somatization disorder
    - Conversion disorder
    - Hypochondriasis
    - Psychogenic pain disorder
  - Dissociative disorders
    - Dissociative amnesia
    - Dissociative identity disorder
    - Depersonalization
  - Eating disorders
  - Personality disorders
    - Paranoid personality disorder
    - Schizoid personality disorder
    - Schizotypal personality disorder
    - Antisocial personality disorder
    - Borderline personality disorder
    - Histrionic personality disorder
    - Narcissistic personality disorder
    - Avoidant personality disorder
    - Dependent personality disorder
    - Obsessive-compulsive personality disorder
  - Gender dysphoria
  - Paraphilic disorders
  - Disorders usually first evident in infancy, childhood, or adolescence
    - Attention-deficit disorders
    - Conduct disorders
    - Anxiety disorders
    - Eating disorders
    - Other childhood disorders
  - Other mental disorders
    - Factitious disorders
    - Impulse-control disorders
    - Adjustment disorders
Treatment of mental disorders
- Historical overview
  - Early history
  - The mental hospital era
  - The biological movement
  - Development of psychotherapy
  - Development of physical and pharmacological treatments
  - Deinstitutionalization
  - Development of behavior therapy
  - Further developments in the mental health profession
- Physiological treatments
  - Pharmacological treatments
    - Antipsychotic agents
    - Antianxiety agents
    - Antidepressant agents
    - Mood-stabilizing drugs
  - Electroconvulsive treatment
  - Psychosurgery
- The psychotherapies
  - Psychotherapeutic approaches
  - Dynamic psychotherapies
    - Psychoanalytic psychotherapy
    - Individual dynamic psychotherapy
    - Brief focal psychotherapy
    - Humanistic and existential psychotherapies
    - Behavioral psychotherapy
    - Cognitive psychotherapy
    - Interpersonal psychotherapy
    - Group psychotherapy
    - Family therapy

References & Edit History Quick Facts & Related Topics

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At a Glance

Sigmund Freud

mental disorder summary

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mental disorder

medicine

Also known as: insanity, madness, mental illness, psychiatric disorder(Show More)

Written by

Stuart C. YudofskyAll

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Britannica Editors

Last updated

Oct. 17, 2026 •History

mental disorder, any illness with significant psychological or behavioral manifestations that is associated with either a painful or distressing symptom or an impairment in one or more important areas of functioning. (Read Sigmund Freud’s 1926 Britannica essay on psychoanalysis.) Mental disorders, in particular their consequences and their treatment, are of more concern and receive more attention now than in the past. Mental disorders have become a more prominent subject of attention for several reasons. They...

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