It is believed that a combination of certain genes and a number of early life risk factors probably leads to subtle abnormalities in brain development, which set the stage for the later development of psychosis. It is unlikely that only one gene can cause psychosis. Instead, a number of genes each play a small role in a person’s risk for developing psychosis. The abnormal brain development that happens early in life among people who later develop psychosis is very subtle and usually remains undetected and quiet. School difficulties and social problems may develop during childhood and adolescence. In addition to the subtle abnormalities in early brain development, additional subtle abnormalities may also happen during the important period of adolescent brain maturation. Research suggests that adolescent drug use, especially marijuana use, increases one’s risk of developing psychosis.
Risk factors for early adolescent drug use in four ethnic and racial groups.