Onset of the disease seems to differ by gender, with men developing the disease earlier in life than women. Schizophrenia occurs worldwide in all cultures and across all socioeconomic classes. Stating that 1 in 100 people is affected by schizophrenia DOES NOT MEAN that 1 in 100 is diagnosed with it. Because schizophrenia is more difficult to diagnose than diseases that have clear physical and biological diagnostic criteria, the disease s prevalence and costs to society may be underestimated. Individual doctors interpretations of diagnosis criteria for schizophrenia may vary.
Overlaps occur in the diagnoses of mental illnesses.
Religious opinions on mental illness vary, causing attitude inconsistencies. Stigma may prevent those with schizophrenia, their families and doctors from seeking a diagnosis. The diagnoses of schizophrenia may not always be recorded accurately. Gender may skew diagnoses, e.g., women may be diagnosed with affective or mood disorders, when they in fact have schizophrenia. Many of the studies done on schizophrenia have been based on small population bases and should not be extrapolated.