Variations in the incidence of schizophrenia: data versus dogma.

The schizophrenia research community has shared a belief that the incidence of schizophrenia shows little variation. This belief is related to the dogma that schizophrenia affects all individuals equally, regardless of sex, race, or nationality. However, there is now robust evidence that the incidence of schizophrenia is characterized by substantial variability. There is prominent variation in the incidence of schizophrenia between sites. The incidence of schizophrenia is significantly higher in males than in females (male:female ratio = 1.4). Migrants and those living in urban areas have a higher incidence of schizophrenia. The incidence of schizophrenia has fluctuations across time. In addition, the prevalence of schizophrenia is also characterized by prominent variation. The realization that schizophrenia is characterized by rich and informative gradients will serve as a catalyst for future research.