If you are unfortunate enough to develop acute chest pain this winter you will probably be assessed by a clinician who will order a battery of tests to determine if your symptoms result from pneumonia, bronchitis, heart disease, or something else. These tests not only can yield a precise diagnosis, they ensure you will receive the appropriate treatment for your specific illness.
If you are unfortunate enough to have a psychotic episode this winter, the process of arriving at a diagnosis will be quite different. In fact, there are not many choices. Most people with a psychotic disorder are labeled as having either schizophrenia or bipolar disorder. The distinction has been in textbooks for a century: schizophrenia (originally dementia praecox) is associated with delusions, hallucinations, an absence of affect, and a chronic course; bipolar (originally manic depressive disorder) can also involve delusions and hallucinations, and ,typically, dramatic swings in mood and a fluctuating course. But outside of textbooks, in the real world of the emergency room or clinic, these distinctions are less clear as many patients do not neatly fit the formal descriptions. Sadly, there are no blood tests or scans to distinguish schizophrenia from bipolar disorder.
While clinicians have become very skilled at assessing symptoms and signs, the absence of diagnostic laboratory tools or biomarkers poses a serious problem in psychiatry. Do all people with a label of schizophrenia have the same disorder? What about the large number of people who appear to have aspects of both schizophrenia and bipolar? Are these disorders, diagnosed exclusively by signs and symptoms, identifying distinct biological entities or could there be many different illnesses with a continuum of psychotic signs and symptoms? These questions are not merely academic. As with chest pain, getting a precise diagnosis is important for selecting the best treatment.