https://www.mayoclinic.org/diseases-conditions/schizophrenia/symptoms-causes/syc-20354443
Causes:
It's not known what causes schizophrenia, but researchers believe that a combination of genetics, brain chemistry and environment contributes to development of the disorder.
Problems with certain naturally occurring brain chemicals, including neurotransmitters called dopamine and glutamate, may contribute to schizophrenia. Neuroimaging studies show differences in the brain structure and central nervous system of people with schizophrenia. While researchers aren't certain about the significance of these changes, they indicate that schizophrenia is a brain disease.
Risk factors
Although the precise cause of schizophrenia isn't known, certain factors seem to increase the risk of developing or triggering schizophrenia, including:
• Having a family history of schizophrenia
• Some pregnancy and birth complications, such as malnutrition or exposure to toxins or viruses that may impact brain development
• [Taking mind-altering (psychoactive or psychotropic) drugs during teen years and young adulthood