Schizophrenia or trauma-related psychosis? Schneiderian first rank symptoms as a challenge for differential diagnosis

schizophrenia. Auditory hallucinations in the ‘third person perspective’ in combination with impaired functioning are sufficient for the diagnosis according to Diagnostic and Statistical Manual of Mental Disorders-IV-text revision and International Classification of Diseases-10. However, identical symptoms can be observed in severe dissociative disorders. This article reflects the history of Schneiderian first rank symptoms, shared and nonshared symptoms of schizophrenia and dissociative disorders and the hypothetical role of traumatic events in the origin of these symptoms. Based on the nonshared psychopathological symptoms such as negative symptoms, formal thought disorder and disorganization, suggestions for the differential diagnosis of both disorders and implications for therapy are outlined.