Is schizophrenia universal?

The question whether schizophrenia occurs in similar forms in different populations and cultures was first raised by Kraepelin at the turn of the century. However, methodological difficulties have impeded for decades the development of comparative cross-cultural research, and it was not until the 1960s that investigations of the kind Kraepelin envisaged became feasible. A major role in launching multi-centre clinical and epidemiological studies of schizophrenia in over 20 countries in different parts of the world has been played by the World Health Organization. The WHO studies have demonstrated that: (I) syndromes of schizophrenia occur in all cultures and geographical areas investigated; (II) their rate of incidence is very similar in the different populations; (III) the course and prognosis of schizophrenia is extremely variable, but outcome is significantly better in the developing countries. These findings have fundamental implications for the conceptualization of schizophrenia and for designing strategies of new research.