Diagnosing schizophrenia circa 2005: how and why?

Since the introduction of the third edition of the Diagnostic and Statistical Manual of Mental Disorders, Third Edition in 1980, schizophrenia has been widely diagnosed with good to excellent levels of reliability. This is no small feat, as prior to the 1970s the reliability of this diagnosis over time and place was very poor. Although there have been some changes in the diagnostic algorithm for schizophrenia with subsequent revisions of the Diagnostic and Statistical Manual of Mental Disorders, there has been little change in the overall classification scheme. However, there has also been relatively little movement toward enhancing the validity of this diagnosis. Although there is broad consensus that what we now call schizophrenia is probably very heterogeneous with respect to underlying etiology and pathophysiology, attempts to identify more valid subtypes or dimensions have not progressed to the point that they are likely to be incorporated into diagnostic systems any time soon. The limited progress in defining more valid disease categories has increasingly important clinical implications as the field moves more and more to treatment by preset algorithms that are typically driven by diagnosis.