The father of psychiatric nosology, Emil Kraepelin, divided severe psychiatric disorders into the episodic mood disorders (i.e., manic-depressive illness or bipolar disorder) and nonepisodic psychotic disorders (i.e., dementia praecox or schizophrenia). Now, 100 years later, we still use this fundamental dichotomy. In his scheme, schizophrenia is the prototypical psychotic illness marked by prominent psychosis in the absence of psychiatric or medical disorders that would explain psychosis; patients who have this disease suffer from some degree of social impairment. In the real world of clinical
cases, patients do not always fit the syndrome of schizophrenia: Some patients experience short periods of illness without obvious impairment; others display rather significant admixtures of mood symptoms. To include cases on the edges of narrowly defined schizophrenia, the term “schizophrenia-spectrum conditions” is sometimes used, although disagreement on what conditions to include persists (e.g., some would include schizotypal personality disorder, others delusional disorder) (see Table 6.1 for the use in this book). Yet another term, “nonaffective psychoses” similarly refers to a spectrum of psychotic disorders that includes all psychotic disorders except those in which psychosis is part of a primary mood disorder.

In this chapter I provide a clinical description of the syndrome of schizophrenia that focuses on its natural history. How to make a clinical diagnosis of schizophrenia using current diagnostic criteria is presented in the next chapter.