Differential diagnosis and comorbid physical illness of schizophrenia

Background: Schizophrenia is a neurodevelopmental disorder that generally develops during adolescence or early adulthood. However, differentiating it from psychosis caused by a physical illness is difficult due to the phenotype-based diagnostic system. In this review, differential diagnosis of schizophrenia and the comorbid physical illnesses of patients with schizophrenia will be discussed. Current Concepts: Psychotic symptoms can be caused by various physical illnesses, and patients with schizophrenia have many physical comorbidities. Symptoms of psychosis can also be expressed by physical illness including brain tumors, encephalitis, temporal lobe epilepsy, autoimmune disease, and genetic disease. For the differential diagnosis of other physical illnesses that can cause psychosis, biological tests are essential. Depending on the cause, antipsychotics and treatment of physical diseases are required. In addition, patients with schizophrenia have many comorbid medical conditions such as obesity, diabetes, cardiovascular disease, but the diagnosis rate is low, and the mortality is higher than that of the general population due to untreated medical diseases. Discussion and Conclusion: The differential diagnoses of schizophrenia and physical illness causing psychosis are important. To decrease the high mortality of patients with schizophrenia, periodic physical condition examinations and mental status examinations should be conducted.