Obviously there is frequent overlap. Understand the distinction between mental and personality disorders. Review and learn the DSM-IV multiaxial diagnostic system. Understand the concepts incidence and prevalence. Incidence refers to the number of new cases per some period of time .
Prevalence refers to the number of existing cases during some specific period of time.
Understand the concepts of sensitivity and specificity . A test is sensitive when it accurately identifies the presence of a disorder in a person who has the disorder. A test is specific when it accurately detects the absence of a disorder in a person who does not have the disorder. The most common disorders were major depressive episode, alcohol dependence, social phobia, and simple phobias. These comorbid people also include the vast majority of people with severe disorders.