1. The key statistics are its prevalence, the age at which it first appears, differences by sex and ethnicity, and the recovery rates.
2. Every figure here is an approximation, because it depends on who reaches a service and how a diagnosis is reached.

Prevalence

1. About one in a hundred people are diagnosed with schizophrenia at some point in their lifetime, which is several hundred thousand people in the UK.
2. The number who have it at any one moment is lower, at well under one in a hundred, because many people recover or have long periods without symptoms.
3. Depression is roughly ten times more common, at around one in ten.
4. Rates are broadly similar across countries and cultures.
   1. Rates are somewhat higher in cities than in the countryside.

Age at first diagnosis

1. Symptoms usually appear for the first time between the late teens and the mid-twenties.
2. For men the peak is around twenty to twenty-five, and for women it tends to fall a few years later.
3. Women also show a second, smaller peak after about forty-five.
4. A first diagnosis in childhood is very rare, and a first diagnosis after sixty is uncommon.
5. Symptoms therefore often arrive while a person is finishing education, starting work and forming relationships.
6. NHS early intervention in psychosis teams exist because acting in the first few years improves the outcome.

Sex differences

1. Men are diagnosed somewhat more often than women, at a ratio of roughly three men to every two women.
2. Men are also diagnosed younger on average, by around three to five years.
3. Men tend to show more negative symptoms such as avolition and flattened emotion, and to have a harder course overall.
4. Women more often have a later start, better functioning beforehand, and a better response to treatment.

Ethnicity and diagnosis rates

1. In the UK, diagnosis rates are much higher among Black Caribbean and Black African people than among the white British population, with some studies reporting several times the rate.
2. Black patients are also more likely to be detained under the Mental Health Act and less likely to be referred by a GP.
3. One explanation is diagnostic bias, where a psychiatrist from a different cultural background reads unfamiliar speech or belief as a symptom.
4. Another is social adversity, since racism, discrimination, poverty and living in a large city all raise the risk of psychosis.
5. Diagnostic bias and social adversity are both thought to contribute to the gap.

Recovery rates

1. About one in five people diagnosed with schizophrenia recover fully, often within around five years of a first episode.
2. Roughly three in five improve a great deal but keep some symptoms, which may come back in relapses.
3. About one in five continue to have troubling symptoms and need long-term support.
4. Recovery is more likely when treatment starts early, medication is continued, and a person has family, housing and work around them.
5. Recovery in this field means living the life a person wants, so someone can be described as recovered while still managing some symptoms.
6. Only a minority face lifelong severe difficulty, and most people diagnosed with schizophrenia improve with treatment and support.

Turning this into marks

1. When two statistics are asked for, make them genuinely separate rather than one figure restated.
2. Give the actual figure, such as about one in a hundred over a lifetime, because writing that schizophrenia is rare does not secure the knowledge mark.
3. Say which statistic the figure is, since a rate of diagnosis and a rate of recovery answer different questions.
4. The mark most often lost is giving the lifetime prevalence figure when the question asked about recovery.