[The schizophrenic spectrum: an epidemiological viewpoint]

In epidemiological terms there is no clear demarcation between health and illness. This is also true for the schizophrenic spectrum, where sub-clinical (sub-syndromal, sub-diagnostic) syndromes embrace schizotypical, schizoid and paranoid personality disorders and personality features, which in the general population are much more prevalent than schizophrenias themselves. Early recognition of risk cases and mild cases is decisive for prophylaxis. Several diagnostic instruments are available for this purpose, but satisfactory confirmation of their predictive power and validity by prospective studies is lacking. Alongside traditional, clinical research on schizophrenia, future epidemiological research, focusing increasingly on the whole schizophrenic spectrum, may be expected to yield important new insights confirming a dimensional rather than a categorical distribution of traits and syndromes and providing powerful arguments against the discrimination and stigmatisation suffered by schizophrenic patients.