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Sex differences

What is incidence?

Incidence refers to how many new cases of schizophrenia there are per population in a specified time period. It is different from prevalence, which refers to how many existing cases there are at a particular point in time, or over a lifetime. Incidence is usually reported as the number of new cases per 100,000 people per year, but this can vary. Differences in the incidence of a disorder can provide clues to its possible causes. For example, a population register with information gained from consensus data helps to identify all adults in a defined area who were born within a certain time period (a cohort). Cross linking this information with a mental health register for the cohort can be used to identify people who received treatment for schizophrenia over particular times. This information provides the incidence of schizophrenia for various age groups within that cohort.

What is the evidence for differences in incidence rates according to sex?

Overall, moderate to high quality evidence finds the incidence of schizophrenia is higher in males than in females. However, this is only apparent in males up until around 40 years of age, then incidence is similar between males and females until about 50 years, then it is higher in females than males over 50 years of age. This is proposed to be due to decreasing oestrogen levels in females over time, as oestrogen is a proposed protective factor for schizophrenia.

August 2020

Last updated at: 2:30 am, 21st August 2020
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Fact Sheet Technical Commentary

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Title Colour Legend:
Green - Topic summary is available.
Orange - Topic summary is being compiled.
Red - Topic summary has no current systematic review available.