A psychiatrist is a physician who specializes in psychiatry, the branch of medicine devoted to the diagnosis, prevention, study, and treatment of mental disorders. Psychiatrists are medical doctors, unlike psychologists, and must evaluate patients to determine whether their symptoms are the result of a physical illness, a combination of physical and mental ailments, or strictly psychiatric.

As a part of the clinical assessment process, psychiatrists may employ a mental status examination; a physical examination; brain imaging such as a computerized tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET) scan; and blood testing. Psychiatrists prescribe medicine, and may also use psychotherapy, although the vast majority do medical management and refer to a psychologist or other specialized therapist for weekly to bi-monthly psychotherapy.