Current genetic, neurobiological, clinical-descriptive and pharmacological data about obsessive-compulsive symptoms (OCS) and/or obsessive-compulsive disorder (OCD) in schizophrenia hypothesize that schizophrenia combined with OCD is more than a mere comorbidity. To prove this hypothesis, “dimensional diagnosis”, based on the identification of a dysfunctional area common to different clinical cases, should replace “categorical diagnosis”, that focuses on discrete parameters that define specific disorders. It is our hope that the DSM-V will make reference to principles based on psychopathological “spectra” because these reflect the integration of pharmacotherapeutic, descriptive and etiopathogenetic aspects (genotypes common to various disorders, temperamental predispositions, neurobiological and chemical alteration). These three aspects explain how obsessive phenomena can develop into delusional phenomena.
