An internist or Internal Medicine doctor is someone who specializes in diagnosing and treating illnesses, diseases, and health problems. Most internists are also primary care doctors and treat patients on a regular basis. They can diagnose and treat common illnesses or more serious problems. Most people see an internist regularly. Those with chronic illnesses may do so on a monthly or even weekly basis. Internists are the most common types of doctors.

Medical professionals who specialize in neuropsychiatry work to help patients who have mental illnesses that can be directly attributed to neurological disorders or problems. This field has grown in recent years as it has become clearer that many mental illnesses are the result of physical problems of the brain. It is a more specialized field than their neurology or psychiatry, and therefore, patients must seek out this specific type of care if their mental illness is related to a brain disorder.