This issue of Psychiatric Annals proposes the use of associated psychiatric syndromes as a basis for a clinical subtyping system for schizophrenia. This proposal rests on two lines of reasoning:
1. The current, classic system for subtyping schizophrenia has weaknesses that compromise its utility for clinicians (eg, its diagnoses give no treatment guidance and are temporally unstable, commonly changing over time) and for scientists (eg, the diagnoses are unstable and they describe groups that are of dubious validity and may not be homogeneous).
2. Associated psychiatric syndromes appear to have some qualities needed for an effective subtyping system (eg, they appear to be stable over time and may offer treatment guidance).
This issue briefly reviews the major efforts at subtyping schizophrenia and what is currently known about associated psychiatric syndromes in schizophrenia. Although much remains to be learned about these syndromes, investigation into their utility as a foundation for a subtyping system appears to be warranted.
In medicine, nosology should rest on etiology and not merely on symptoms or clinical appearances. There is reason for optimism that new developments, particularly noninvasive imaging, will help establish the biological foundations of schizophrenia. In contrast, the approach offered in this issue rests on clinical symptomatology and so may be found deficient. However, we must keep several things in mind when judging the potential utility of such a nosologic system. First, although psychiatry has developed many fine and elegant theories, definitive proof of the etiology of any specific disorder has not been demonstrated. Second, schizophrenia, generally recognized as clinically heterogeneous, may be etiologicalIy heterogeneous as well. In other words, there may not be a single etiology for schizophrenia. Until etiology is firmly established, we must strive to develop classification systems that conform as closely as possible to the observable phenomena.
The search for an underlying etiology must not be allowed to produce disdain for observable phenomena. Our faithfulness to these observable phenomena may bring us closer to the underlying processes and may help in the effort to determine etiology. Schizophrenia is, in part, a disturbance of behavior and therefore is, at least in part, observable.
Schizophrenia is also a disorder of trtinking (disordered thought, delusions, and cognitive impairment) and of experience (hallucinations), for this is how it is defined. Any etiology for this protean disorder must encompass these behavioral and experiential disturbances.
Perhaps one day there will be firmly established biological bases for the psychoses, but until then we must describe carefully what we can see and follow the clues we find there to determine underlying processes. It is hoped that this issue will stimulate further study along these lines.