The spectrum concept of schizophrenia posits that a number of psychopathologic states, both psychotic and nonpsychotic, may share some genetic basis with schizophrenia, and may therefore constitute, together with schizophrenia itself, a genetic spectrum of schizophrenic disorders.
While this is a valuable and promising research concept, its application to diagnostic practice could broaden the boundaries of schizophrenia to include patients with other conditions, thus rendering a larger population at risk for the untoward effects of the schizophrenia diagnosis itself. This may have already occurred in the Soviet Union, where a diagnostic system derived from a variant of the spectrum concept is used in routine diagnostic practice.
The adoption of a spectrum-based diagnostic system should await further research on the boundaries of the spectrum, and more detailed descriptions of confirmed spectrum states.
Reich W. The Spectrum Concept of SchizophreniaProblems for Diagnostic Practice. Arch Gen Psychiatry. 1975;32(4):489-498. doi:10.1001/archpsyc.1975.01760220101010