Just what is a mental disorder? Diagnosing an emotional problem doesn’t come about with a simple chemical analysis or blood test. Psychiatrists, psychologists, and other mental health professionals typically refer to a document called the Diagnostic and Statistical Manual (DSM) for determining the criteria for any specific diagnosis of an emotional disorder.
The reason professionals do so is to communicate with each other by using an agreed-on set of standards, which the DSM provides. For example, the most recent revision of the DSM states that to have a diagnosis of major depressive disorder, you must suffer from depression for at least two weeks and experience five or more symptoms. Well, some people have only four symptoms, but the symptoms continue for 12 weeks or more. Does that mean that these folks don’t have a major depressive disorder? That’s one of the reasons the DSM is controversial; it isn’t always clear if someone perfectly fits a given diagnosis.
Therefore, the DSM is constantly under revision and is considered imperfect in many ways. Professionals continue to disagree with aspects of the diagnostic criteria.