In a pilot study with 55 inpatients, primarily admitted for cocaine addiction, the following hypotheses were found: Patients with cocaine addiction and comorbide core schizophrenia (according to Kreapelin, n=17) respond completely different on cocaine use than all other groups of patients including a schizophrenia spectrum group (without core schizophrenia according to Kraepelin). When using cocaine the schizophrenic patients do not experience new psychotic symptoms and existing symptoms do not get worse. Most of them are less bothered of negative symptoms and some of them are, even more, less bothered of positive symptoms. In all other patients with various comorbidity (n=28) and without comorbide psychiatric disorders (n=10) positive psychotic symptoms occur dependent on the dosage of cocaine. In some of them the positive symptoms are also triggered by stress alone. The symptoms occurred in a dosage dependent hierarchical structure: mistrust - delusions of reference with fear - delusions of persecution and illusions with anxiety or panic - threatening voices and noises - disorganized and catatonic behavior.

The psychopathology induced by cocaine prooved to be similar to one of the core symptoms of cycloid psychoses.

The hypothesis is raised that there is an individual genetically and/or environmentally caused liability to the developing of positive psychotic symptoms under various stress factors including drugs. These reactive psychoses have to be distinguished from schizophrenia. Their relationship to the spectrum of cycloid psychoses is discussed.