A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitting, or occur as single episodes. Many disorders have been described, with signs and symptoms that vary widely between specific disorders. Such disorders may be diagnosed by a mental health professional, usually a clinical psychologist or psychiatrist. The causes of mental disorders are often unclear. Theories may incorporate findings from a range of fields. Mental disorders are usually defined by a combination of how a person behaves, feels, perceives, or thinks. This may be associated with particular regions or 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.Services are based in psychiatric hospitals or in the community, and assessments are carried out by mental health professionals such as psychiatrists, psychologists, psychiatric nurses and clinical social workers, using various methods such as psychometric tests but often relying on observation and questioning. Treatments are provided by various mental health professionals. Psychotherapy and psychiatric medication are two major treatment options. Other treatments include lifestyle changes, social interventions, peer support, and self-help. In a minority of cases, there might be involuntary detention or treatment.
Asylum "inmates" were increasingly referred to as "patients", and asylums were renamed as hospitals. Europe and the United States
Early in the 20th century in the United States, a mental hygiene movement developed, aiming to prevent mental disorders. Clinical psychology and social work developed as professions. World War I saw a massive increase of conditions that came to be termed "shell shock". World War II saw the development in the U.S. of a new psychiatric manual for categorizing mental disorders, which along with existing systems for collecting census and hospital statistics led to the first Diagnostic and Statistical Manual of Mental Disorders. The International Classification of Diseases (ICD) also developed a section on mental disorders. The term stress, having emerged from endocrinology work in the 1930s, was increasingly applied to mental disorders. Electroconvulsive therapy, insulin shock therapy, lobotomies and the neuroleptic chlorpromazine came to be used by mid-century. In the 1960s there were many challenges to the concept of mental illness itself. These challenges came from psychiatrists like Thomas Szasz who argued that mental illness was a myth used to disguise moral conflicts; from sociologists such as Erving Goffman who said that mental illness was merely another example of how society labels and controls non-conformists; from behavioral psychologists who challenged psychiatrys fundamental reliance on unobservable phenomena; and from gay rights activists who criticised the APAs listing of homosexuality as a mental disorder.