Definitions for all mental diseases are defined in the DSM as best they can. Originally there were fewer recognized disorders; but as they learn and refine the data the definitions change, and the list of disorders gets longer. Making a diagnosis is more art than science because everyone is different and behaviors overlap etc.

Then there are Legal definitions of mental disorders. Although there are similarities, the law has a different agenda there are differences from the DSM. http://en.wikipedia.org/wiki/Psychopathy_Checklist#Comparison_with_psychiatric_diagnoses

In the field of literature authors take the bits and pieces of the world and reassemble them to serve the story we are telling. Though some authors use careful research, a literary diagnosis may have nothing in common with medical or legal definitions.