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Glossary of Terms

Mental Disorder

For Experts

  • A clinically significant disturbance in an individual’s cognition, emotion regulation, or behaviour that reflects dysfunction in the psychological, biological, or developmental processes underlying mental functioning where the person’s condition meets DSM or ICD diagnostic criteria.
  • Associated with significant distress in social, occupational, or other activities.
  • Causes of mental disorders are thought to be multiple and interlinked, not linear, and related to various combinations of traumatic events or potentially psychologically traumatic events, genetics, biology, diet, socioeconomic factors, physical health conditions, physical environmental factors, and others. 
  • The symptoms and signs are not better explained by a physical health condition or the effects of a substance.
  • Common, culturally consistent responses to a common stressor or loss, such as the death of a loved one, which do not meet accepted diagnostic criteria, are not mental disorders. 
  • Socially deviant behaviour (e.g., political, religious, or sexual) and conflicts that are primarily between the individual and society are not mental disorders unless the deviance or conflict results from a dysfunction in the individual which meets accepted diagnostic criteria.

For General Public

  • A type of mental health condition that meets accepted criteria for diagnosis published in the DSM or ICD.
  • Criteria for diagnosis include impaired functioning in social, workplace, or other activities.
  • A diagnosis of a mental disorder might be made if the diagnostic criteria best explain a person’s current condition.
  • Mental disorders are thought to be caused by the interactions of different combinations of factors; for example,  potentially psychologically traumatic events or stressors, genetics, biology, socioeconomic factors, physical health conditions, or physical environmental factors.
  • A person could receive a diagnosis of more than one mental disorder at a time.
  • Does not include normal responses to common stressors like the loss of a loved one, workplace pressures, living with a physical health condition, or chronic pain.
  • Mental disorder is currently the preferred term instead of mental illness.

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