We should not let confusion about differentiating schizophrenia from other psychoses detract from the fact that schizophrenia is a universal condition and an ancient one. Typical cases may be distinguished in the medical writings of ancient Greece and Rome, and the condition occurs today in every human society. While the content of delusions and hallucinations varies from culture to culture, the form of the illness is similar everywhere. Two World Health Organization studies, applying a standardized diagnostic approach, have identified characteristic cases of schizophrenia in developed and developing world countries from many parts of the globe.

More surprisingly, one of these studies demonstrated that the rate of occurrence of new cases (the incidence) of the condition is similar in every country studied from India to Ireland. However, since both death and recovery rates for people with psychosis are higher in the Third World, the point prevalence of schizophrenia (the number of cases to be found at any time) is lower in the Third World – around 3 per 1,000 of the population compared to 6 per 1,000 in the developed world. The risk of developing the illness at some time in one’s life (the lifetime prevalence) is a little higher – around one percent of the population in the developed world.