%0 Journal Article %T Comorbid Obsessive-Compulsive Symptoms in Schizophrenia: Insight into Pathomechanisms Facilitates Treatment %A Mathias Zink %J Advances in Medicine %D 2014 %R 10.1155/2014/317980 %X Insight into the biological pathomechanism of a clinical syndrome facilitates the development of effective interventions. This paper applies this perspective to the important clinical problem of obsessive-compulsive symptoms (OCS) occurring during the lifetime diagnosis of schizophrenia. Up to 25% of schizophrenia patients suffer from OCS and about 12% fulfil the diagnostic criteria of obsessive-compulsive disorder (OCD). This is accompanied by marked subjective burden of disease, high levels of anxiety, depression and suicidality, increased neurocognitive impairment, less favourable levels of social and vocational functioning, and greater service utilization. Comorbid patients can be assigned to heterogeneous subgroups. It is assumed that second generation antipsychotics (SGAs), most importantly clozapine, might aggravate or even induce second-onset OCS. Several epidemiological and pharmacological arguments support this assumption. Specific genetic risk factors seem to dispose patients with schizophrenia to develop OCS and risk-conferring polymorphisms has been defined in SLC1A1, BDNF, DLGAP3, and GRIN2B and in interactions between these individual genes. Further research is needed with detailed characterization of large samples. In particular interactions between genetic risk constellations, pharmacological and psychosocial factors should be analysed. Results will further define homogeneous subgroups, which are in need for differential causative interventions. In clinical practise, schizophrenia patients should be carefully monitored for OCS, starting with at-risk mental states of psychosis and longitudinal follow-ups, hopefully leading to the development of multimodal therapeutic interventions. 1. Introduction 1.1. Insight into Biological Mechanisms of Diseases 1.1.1. Mental Disorders Are a Major Cause of Disability Clinical research in psychiatry has achieved some important progress both in pathogenetic concepts and in therapeutic interventions over the past decades. However, compared to other medical illnesses and disciplines biological mechanisms of psychiatric disorders are still poorly understood. This leads to a lack of innovative therapeutic interventions in psychiatry compared, for example, to general medicine [1]. Relating to schizophrenia, the market approval of first and second generation antipsychotics (FGA, SGA) has to be acknowledged as the last important and seminal innovation in treatment. Besides pharmacological interventions [2], cognitive behavioral therapy (CBT) is still scarcely implemented in the clinical management, although it %U http://www.hindawi.com/journals/amed/2014/317980/