Noun

Singular mental illness

Plural countable and uncountable; plural mental illnesses

mental illness (countable and uncountable; plural mental illnesses)

1. (uncountable) The property of being mentally ill; mental disorders taken as a whole.
   • 2006, R. Keith Sawyer, Explaining Creativity: The Science of Human Innovation, Oxford University Press US, ISBN 9780195161649, page 87:

     Such studies show that geniuses are not any more likely to suffer from mental illness than the rest of us.

2. (countable) A mental disorder.
   • 2002, Vikram Patel, Where There is No Psychiatrist: A Mental Health Care Manual, RCPsych Publications ISBN 978-1-901242-75-1, page 70:

     Epilepsy is not a mental illness. It is caused by electrical changes in the brain.

A mental disorder or mental illness is a psychological or behavioral pattern associated with distress or disability that occurs in an individual and is not a part of normal development or culture. The recognition and understanding of mental health conditions has changed over time and across cultures, and there are still variations in the definition, assessment, and classification of mental disorders, although standard guideline criteria are widely accepted.

Over a third of people in most countries report meeting criteria for the major categories at some point in their life. The causes are often explained in terms of a diathesis-stress model and biopsychosocial model. Services are based in psychiatric hospitals or in the community, and mental health professionals diagnose individuals by various methods, often relying on observation and questioning in interview.

Psychotherapy and psychiatric medication are two major treatment options as are social interventions, peer support and self-help. In some cases there may be involuntary detention and involuntary treatment where legislation allows. Stigma and discrimination add to the suffering associated with the disorders, and various social movements campaign for change.