L’approche dimensionnelle versus l’approche catégorielle dans le diagnostic psychiatrique : aspects historiques et épistémologiques

RésuméL’opposition méthodologique entre l’approche catégorielle et l’approche dimensionnelle apparaît être l’un des enjeux principaux pour la réactualisation du savoir psychiatrique actuel. Après une période exclusivement marquée par l’abord catégoriel dans le Manuel Diagnostique et Statistique des troubles mentaux, DSM-III (1980) et le DSM-IV (1994), l’abord dimensionnel revient aujourd’hui de façon complémentaire avec des modèles spectraux (le spectrum affectif chez Akiskal, le spectrum schizophrénique chez Parnas, ou des dimensions de la personnalité chez Cloninger), anticipant l’élaboration du futur DSM-V, prévu pour 2013. Dans cet article, nous proposons de parcourir l’interaction entre ces deux abords dans la construction de notre édifice nosographique, dans une perspective historique.

BackgroundThe methodological opposition between the categorical approach and the dimensional approach appears as the main issue for the reorganization of current psychiatric knowledge. After a period exclusively marked by the categorical approach in the Diagnostic and Statistical Manual, DSM-III (1980) and the DSM-IV (1994), the dimensional method comes back today complementarily with spectral models (the affective spectrum by Akiskal, the schizophrenic spectrum by Parnas, or dimensional personality by Cloninger), anticipating the development of the future DSM-V, scheduled for 2013.MethodologyIn this article, we browse the interaction between these two approaches in the construction of our nosographic building, in a historical perspective, from Pinel and Kraepelin through Krestchmer's model to nowadays spectral classifications. Both approaches are compared in an epistemological way, with its pros and cons, followed by final conceptual discussion.ObjectiveTo deliver an epistemological description of both approaches, with pros and cons of these different methods.ResultsHistorical perspective shows how psychiatry begins with categorical classification, which is later replace by dimension taxonomy, since second decade of xxth century. Most symptoms are dimensional in nature, and can be transformed into a category by setting a cutoff point. Now, after excessive classification and clinical reductionism applied since DSM-III, dimensional approach is emerging to supply these weaknesses, proposing a more sensible description about mental disorders and their courses. Dimensional approach advantages are a certain facility to explore interpersonal differences without artificial cut-offs, and clinical flexibility. A principal disadvantage is the multiplicity of proposed dimensions, without consensus between different theories. In the other hand, categorical method is familiar to us, and is based on solid clinical empirical data. By the way, clinicians say “the more they know their patients, the more they find it difficult to insert them into a category”, the map is not the territory. In conclusion, both approaches must coexist, being each one complementary to each order.