Schizophrenia affects almost 1% of the general
population—or 1 out of every 100 people.1 It usually
appears in late adolescence or the early 20s, although it can first appear in
the mid-30s. It is rare for schizophrenia to occur prior to age 10 or after age
40, although it does happen.
Schizophrenia is found equally in women and men. It often emerges
earlier in men (teens to 25 years) than women (ages 25 to 35). Schizophrenia
may run in families (genetic
disorder), although people with no family history can develop the
disease.
A person born in a city is at a higher risk for developing
schizophrenia than a person born in a rural area.1
Also, people born in the winter and early spring are more likely to develop
schizophrenia than people born in the late spring and summer.1 One theory used to explain this risk factor is that
schizophrenia may be linked to a common winter or early spring
viral infection; the virus may interfere with brain
development in an unborn baby.
New studies indicate that the risk for developing schizophrenia also
increases if a father was over the age of 50 when his baby was
conceived.2
For unknown reasons, people with schizophrenia who live in less
developed countries have a better outcome with this disease than those living
in developed countries.3 One thought is that people in
underdeveloped countries have more family support available, have fewer outside
demands, and their behaviors are more readily accepted by their communities.