Obsession in the strict sense: A helpful psychopathological phenomenon in the differential diagnosis between obsessive-compulsive disorder and schizophrenia.

The paper presented follows the hypothesis that differentiation between obsessive-compulsive disorder and schizophrenia is possible only by focusing on the single phenomenon of obsession. The statement of a nosological specificity of obsession, called obsession in the strict sense, is set against the current views of ICD-10 and DSM-IV of obsession as a ubiquitous, non-specific phenomenon appearing in comorbidities. In the succession of the paper, the historical development of these two very different views and their clinically mixing is reconstructed. The phenomenological clarification of the structure of the obsessive phenomena leads to the term of obsession in the strict sense. The distinction between obsessive-compulsive disorder and schizophrenia can take place at the psychopathological interface between obsession in the strict sense and delusional idea. The examination of the literature on the connection between obsessive-compulsive disorder and schizophrenia shows that there is no definitive connection between obsession in the strict sense and schizophrenia. Finally, some case reports are presented to sharpen clinical suspicion for other possibly wrong diagnoses.