1 3 7 ear Colleagues, For the best part of the last two centuries renowned psychiatrists have invested considerable energy in the attempt to develop a perfect classification of mental disorders. This has proved almost as elusive as the quest for the Holy Grail in medieval literature. One reason for this lack of success is probably the fact that the cause of most mental disorders is unknown; consequently, it was, and probably still is, impossible to construct a classification on an etiological basis.The validity of such classifications is often short-lived as they are soon superseded by the emer- gence of new theories.The classifications of the previous decades have withstood the test of time very poorly. For instance, those of the sixties and seventies now seem too heavily influenced by the prevailing ideologies of the time. One may venture that the psychiatric nomenclatures that were taught in medical schools until 1980—the year when the Diagnostic and Statistical Manual of Mental Disorders,Third Edition (DSM-III) was published by the Ameri- can Psychiatric Association—offered no clear improvement over what the German psychiatrist Emil Kraepelin had already proposed in the 7th and 8th editions of his Textbook of Psychiatry in 1903 and 1915. Because of this impossibility of achieving a valid etiological classification of mental disorders, our current diagnostic systems, such as the International Classification of Diseases, 10th Revision (ICD-10) of the World Health Organization, or the 4th edition of the DSM, have deliberately adopted a descriptive and “atheoretical” stand- point—that is, they are neutral with respect to etiological theories. Such an approach lessens the risk of generat- ing nomenclatures based on assumptions that will be disproved by future research. However, we often tend to lose track of a premise paramount in the mind of the creators of the DSM or ICD, namely, that although diagnostic nomenclatures are supposed to facilitate communication, they are not synonymous with real diseases. The cate- gories listed in DSM-IV or ICD-10 are often heterogeneous, and the diseases underlying them are often unknown. A simple term like schizophrenia or major depression may designate distinct illnesses differing in etiology, course, and response to treatment. Oblivious to the fact that psychiatric nomenclatures were devised primarily for communication and statis- tics—rather than research and science—pharmaceutical companies, drug regulatory agencies, and national health authorities tend to extend their field of application to situations where they no longer are valid. This confusion between diagnostic categories and real diseases has stultifying effects on drug development, health care funding, and approval of new drugs. Thus, a diagnostic label is now often misused to determine which type of drugs the physician may give his patients and how long he is allowed to keep them in hospital.A diagnostic code cannot pre- dict the response to pharmacological treatment and has only limited usefulness for clinical drug trials. Insistence on using traditional diagnostic categories may hamper the discovery of innovative drugs. Possible ways of improving diagnosis for research and treatment purposes might include: (i) weighting symp- toms according to their duration, severity, and mode of onset, and better defining their hierarchical relationships; (ii) placing more emphasis on detailed patient life histories (psychobiographies) and personality assessments, which the mere juxtaposition of Axis I and II diagnoses currently fails to adequately take into account; and (iii) charac- terizing patients in drug trials by complementing the imprecise diagnostic categories now in use with additional information from psychometric testing, pharmacogenetics, neurobiology, electrophysiology, brain imaging, etc. Since diagnostic classification occupies such a fundamental place in our clinical practice and the treatment of our patients, we have elected to devote this issue of Dialogues in Clinical Neuroscience to the “transnosologi- cal” approach. Sincerely yours, Jean-Paul MACHER, MD Marc-Antoine CROCQ, MD E d i t o r i a l D
Vol 1 n° 3 - Nosology and Nosography
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