A mental illness is a diaognosis of a behavioural or mental mattern that can cause suffering or a poor ability to function in ordinary life. Such features may be persistent, relapsing and remitting, or occur as a single episode. Many disorders have been described, with signs and sympttoms that vary widely between specific disorders.
The causes are often unclear. They're usually defined by a combination of how a person behaves, feels, perceives or thinks. This can be associated with particular functions of the brain, often in a social context. A mental disorder is one aspect of mental health. Cultural and religious beliefs as well as social norms should be taken into account when making a diagnosis.
Psychotherapy and psychiatric medication are two major treatment options. Other treatments include social interventions, peer support and self-help. In a minority of cases there might be involuntary detention or treatment. Prevention programs have been shown to reduce depression.
Common mental disorders include depression, which affects about 400 million, dementia which affects about 35 million, and schizophrenia, which affects about 21 million people globally. Stigma and discrimination can add to the suffering and disability associated with mental disorders, leading to various social movements attempting to increase understanding and challenge social exclusion.