Psychiatry is a medical specialty which exists to study, prevent, and treat mental disorders in humans. Psychiatric assessment typically involves a mental status examination and taking a case history, and psychological tests may be administered. Physical examinations may be conducted and occasionally neuroimages or other neurophysiological measurements taken. Diagnostic procedures vary but official criteria are listed in manuals, the most common being the ICD from the World Health Organization and the DSM from the American Psychiatric Association. Psychiatric medication is a central treatment option, which is largely unique to psychiatry along with rarer procedures such as Electroconvulsive therapy. Psychotherapy is also a major treatment option in psychiatry, although it is also the speciality of other mental health professions. Psychiatric services may be provided on an inpatient or outpatient basis. In certain authorized cases this may be done on an involuntary basis. Both the research and clinical application of psychiatry are considered interdisciplinary. Because of this, various subspecialties and theoretical approaches exist. Psychiatrists can be considered physicians who specialize in the doctor-patient relationship utilizing some of medicine's newest classification schemes, diagnostic tools and treatments.

Psychiatry can be said to have originated in the 5th century BC, while the first hospitals for the mentally ill were created in the Middle Ages. The 18th century saw the development of psychiatry as a recognized field and mental health institutions came to utilize more elaborate, as well as some more humane, treatments. The 19th century saw a massive increase in patient populations. The 20th century saw a rebirth of a biological understanding of mental disorders as well the introduction of disease classifications and psychiatric medications. An anti-psychiatry movement emerged in the 1960s and a shift led to the dismantling of state psychiatric hospitals in favor of community treatment. There have been changes in psychiatric diagnoses and treatments and in the balance between the biological and social sciences. Research has continued looking into the origins, classification, and treatment of mental disorders.

Theory and focus

"Psychiatry, more than any other branch of medicine, forces its practitioners to wrestle with the nature of evidence, the validity of introspection, problems in communication, and other long-standing philosophical issues" (Guze, 1992, p.4).