Vol 1 n° 3 - Nosology and Nosography
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Nosological classification in psychiatry, as it is currently applied, does not facilitate biological and psychopharma- cological research. • Syndromal acuity has disappeared. Consequently, it is impossible to determine: (i) whether a particular drug affects a particular symptom configuration; (ii) what exact- ly the behavioral correlate of a particular biological dis- turbance is. The problem of unfocused diagnoses is great- ly magnified by the phenomenon called comorbidity. • The  boundary  between  distress  and  disorder  is  ill- defined. • Symptom configuration and certain nonsymptomatolog- ical variables such as duration and severity are prema- turely linked, so as to conceptualize categorical entities. The validity of those constructs has not been sufficiently demonstrated. This undermines the validity of biological studies and leads to “nosologomania,” ie, an ever-grow- ing series of undervalidated psychiatric “disorders.” • Symptoms are grouped horizontally as if they all had the same  diagnostic  “valence.”  This,  however,  is  highly unlikely. • The nosological disease model is unconditionally and uncritically accepted. Alternative models are ignored, particularly the reaction-form model, though it has sub- stantial heuristic value, and deserves to be thoroughly scrutinized. (Research) strategies to remedy this situation are pointed out. Premises of the nosological disease model he nosological disease model has dominated psychiatry   ever   since   its   introduction   in   1863   by Kahlbaum.1 However, this model is not an empirical one, based as it is on the core premise that disturbances of the “psychic apparatus” manifest themselves as discrete entities. In actual fact, this core premise itself rests on two “subpremises.” The first “subpremise” is that psychiatric disorders are characterized by a particular symptomatology, course, out- come, treatment response, and, in principle, pathophysi- ology.The words “in principle” are important to stress that little is known, so far, about the neurobiological basis of mental disorders.The word “particular” implies that men- tal disorders are intrinsically stable, so that recognizing a particular type of syndrome allows reliable predictions to be made concerning course, outcome, treatment response, and (in principle) pathophysiology, and, conversely, that if the pathophysiology is known, then predictions can be made relative to possible type(s) of resulting syndrome(s), course, outcome, and treatment response. The second “subpremise” postulates that each disease entity  can  be  distinguished  and  individualized  with respect to neighboring diagnostic constructs. It is therefore based on this core premise and its two attendant “subpremises” that mental diseases have been conceived of as discrete entities, and that, accordingly, diverse taxonomic classifications of mental disorders have been put forward. The impact of classification on psychophar- macology and biological psychiatry Herman M. van Praag, MD, PhD Keywords: diagnosis; classification; nosology; reaction-form disease model; comorbidity; primary psychiatric symptom; secondary psychiatric symptom; psychogenesis; “nosologomania” Author affiliations: Department of Psychiatry and Neuropsychology Maastricht University, The Netherlands Address for correspondence:  Prof Herman M. van Praag, Department of Psychiatry and Neuropsychology, University Hospital, Maastricht University, PO Box 5800, 6202AZ MD Maastricht, The Netherlands (e-mail: secr.apc@spsy.azm.nl) T 1 4 1 S t a t e   o f   t h e   a r t