Mental disorder or mental illness is a psychological or behavioral pattern that occurs in an individual and is thought to cause distress or disability that is not expected as part of normal development or culture. The recognition and understanding of mental disorders have changed over time and across cultures. Definitions, assessments, and classifications of mental disorders can vary, but guideline criteria listed in the ICD, DSM and other manuals are widely accepted by mental health professionals. Categories of diagnoses in these schemes may include dissociative disorders, mood disorders, anxiety disorders, psychotic disorders, eating disorders, developmental disorders, personality disorders, and many other categories. In many cases there is no single accepted or consistent cause of mental disorders, although they are often explained in terms of a diathesis-stress model and biopsychosocial model. Mental disorders have been found to be common, with over a third of people in most countries reporting sufficient criteria at some point in their life. Mental health services may be based in hospitals. Mental health professionals diagnose individuals using different methodologies, often relying on case history and interview. Psychotherapy and psychiatric medication are two major treatment options, as well as supportive interventions. Treatment may be involuntary where legislation allows. Several movements campaign for changes to mental health services and attitudes, including the Consumer/Survivor Movement. There are widespread problems with stigma and discrimination.

History

Classification

main: Classification of mental disorders

The definition and classification of mental disorder is a key issue for the mental health professions and for users and providers of mental health services. Most international clinical documents use the term "mental disorder" rather than "mental illness". There is no single definition and the inclusion criteria are said to vary depending on the social, legal and political context. In general, however, a mental disorder has been characterized as a clinically significant behavioral or psychological pattern that occurs in an individual and is usually associated with distress, disability or increased risk of suffering. The term "serious mental illness" (SMI) is sometimes used to refer to more severe and long-lasting disorder. A broad definition can cover mental disorder, mental retardation, personality disorder and substance dependence. The phrase "mental health problems" may be used to refer only to milder or more transient issues. There is often a criterion that a condition should not be expected to occur as part of a person's usual culture or religion. Nevertheless, the term "mental" is not necessarily used to imply a distinction between mental (dys)functioning and brain (dys)functioning, or indeed between the brain and the rest of the body.