Anxiety disorders in schizophrenia

Data regarding the co-occurrence of anxiety symptoms or syndromes in schizophrenia is scant. Hierarchical assumptions embedded in diagnostic systems and methodologic difficulties hamper the development of studies on accessory symptomatology outside of the core positive-negative-disorganized symptoms. Recent studies have repeatedly challenged these assumptions by presenting data on comorbid disorders in schizophrenia. We review the current knowledge about anxiety comorbidity in schizophrenia, and its relative prevalence, relevance, and treatment. A computerized search of the literature published from 1966 to July 2003 was conducted on Medline using the word "schizophrenia" and the words from the names of each anxiety disorder listed in DSM-IV, one at a time. Only studies including exclusively the diagnosis of schizophrenia were included. Only 15 studies were dedicated to the subject of anxiety comorbidity prevalence in schizophrenia. The most studied comorbidities were obsessive-compulsive disorder (OCD) and panic disorder, and most reports suggested them to be highly prevalent in schizophrenia. Posttraumatic stress disorder (PTSD) was the least studied (N = 2). Except for two pharmacologic studies in OCD, there were no double-blind randomized controlled trials regarding the treatment of anxiety in schizophrenia. Most case reports and open label trials tried conventional treatment for anxiety disorders with some degree of success. The literature indicates that anxiety comorbidities are prevalent in schizophrenia and conventional treatment for anxiety can help alleviate the symptoms in those patients. However, the body of data provided by research so far is still far from allowing evidence-based conclusions. Large studies with operationalized criteria, as well as comprehensive assessments of treatment response and outcome are needed to clarify the relationship between anxiety disorders and schizophrenia.