ABSTRACT
Schizophrenia has been recognized for over 100 years as a form of severe mental illness, typically, although not always, showing an onset in late adolescence or early adulthood. Extensive biological research searching for a unique diagnostic marker has failed to yield a means of diagnosing the illness from a medical test. Accordingly, clinicians remain wholly dependent on the observation of clinical symptom clusters to diagnose the disorder. Since schizophrenia may represent a complex syndrome with diverse etiological bases and disorder outcomes, the identification of specific symptom clusters is vital in the understanding of the nature of the disorder.
