The concept of mental disorder is determined by many factors, including the historical context, cultural influence, level of scientific knowledge and capacity to carry out scientific enquiry, level of education in certain circumstances, as well as many others. In putting together a method of classification of mental disorders, the expert’s duty is primarily that of capturing and remaining faithful to the current level of knowledge in the subject, acknowledging that, in a matter of time, some or all the above factors could change to variable degrees, making what was clear as a mental disorder a few decades previously less clear in the next edition of the classification system.