[Are the current concepts of obsessive disorders a novelty? From Westphal (1877) and Thomsen (1895) to ICD-10 and DSM-5].

In German-speaking countries it was Carl Westphal who in 1877 offered the first precise definition of obsessive ideas and distinguished obsessive compulsive disorder (OCD) as an independent disorder in its own right. The criteria mentioned by him for establishing OCD gave rise to a debate on the character and classification of OCD but were not fully acknowledged by his colleagues at the time. In 1895 Westphal's student Robert Thomsen tried to substantiate all points in his teacher's theory that had raised criticism. Thus the works by Westphal and Thomsen are most relevant for the current conceptualization and definition of OCD, for they laid the basis for the present phenomenology, definition and classification of OCD according to ICD-10 and DSM-5. Apart from phenomenologically differentiating between obsessions (i.e. obsessive thoughts and impulses) and compulsions (i.e. compulsive actions and inhibitions), Westphal and Thomsen also laid the basis for most of the current diagnostic criteria. Thomsen led the way to current classifications by subdifferentiating OCD as an illness on its own on the one hand and obsessions and compulsions as symptoms accompanying other conditions on the other.