what age is schizophrenia usually diagnosed
1 The average age of onset is 18 in men and 25 in women. 2  Schizophrenia onset is quite rare for people under 10 years of age, or over 40 years of age. 3  The diagram below demonstrates the general age of onset trends for schizophrenia in men and women, from a representative study on the topic. Over 250,000 diagnosed cases in Britain. 2  Rates of schizophrenia are generally similar from country to countryabout .5% to 1 percent of the population (there are variations-but the variance is difficult to track due to differing measuring standards in many countries, etc.).