The epidemiology of paranoid schizophrenia.

Epidemiological data available on paranoid schizophrenia are noteworthy for their paucity and poor quality. Although it is commonly said that the paranoid subtype is less common in developing countries, published studies are contradictory. It has also been said that paranoid schizophrenia occurs more frequently among educated persons, but the evidence is not conclusive. Two Scandinavian studies suggest that the paranoid subtype increased in frequency during this century. Assertions that some cultures produce large numbers of paranoid persons are of great interest since schizophrenic symptomatology is partly dependent on culture. The most famous such culture, the Dobuans, are found to be a product of ethnographic bias and probably do not exist as described. This leaves the question of cultural influence on paranoid schizophrenia wide open. Two studies on the seasonality of paranoid schizophrenic births found that their birth pattern does not differ from the seasonal pattern previously established for schizophrenic births as a whole. It is concluded that the epidemiology of paranoid schizophrenia is an area of potentially fruitful inquiry and one that is mostly terra incognita.