Prevalence of depression in schizophrenia and related disorders

The symptoms of schizophrenia involve positive symptoms (delusions and hallucinations), negative symptoms (apathy, withdrawal, paucity of thought and restriction of affect), disorganization symptoms (disorganized thoughts and actions) and cognitive impairment (memory, attention, working memory, problem solving, processing speed, and social cognition). Schizophrenia patients have a limited and solitary existence, in addition to high rates of unemployment, low income, and poor physical health. The misuse of alcohol and illicit substances is prevalent among schizophrenia patients. All of these factors are related to the development of depressive symptoms in schizophrenia patients. Depression can be associated with suicidal ideation and is often undiagnosed by clinicians. Antidepressants, along with antipsychotics, not only have a therapeutic effect on depressive symptoms in schizophrenia, but they also have side effects. Some of the atypical antipsychotic drugs seem to exhibit antidepressant effect but the usefulness of these drugs in the treatment of persistent depressive symptoms in schizophrenia has not been established. In this study, we review factors related to the development of depression as well as the role of treatment in ameliorating depressive symptoms in schizophrenia patients.