Trends in the frequency of schizophrenia by different diagnostic criteria

The authors report results of rediagnoses of 128 cases from two decades (1932-1941 and 1947-1956) by clinicians using the Research Diagnostic Criteria as guidelines and compare these results to rediagnoses by clinicians in a previous study using more general guidelines. Although hospital records indicated an increased frequency of schizophrenia over the two decades, the rediagnosticians found no change or a decrease. Severity of symptoms did not change during the two decades, but patients in the second decade showed more borderline symptoms, leading to more diagnostic disagreement. The authors conclude that changes in diagnostic criteria and pateints' conditions influence admission trends for schizophrenia.