The cause of schizophrenia is unknown. Scientists think that schizophrenia may develop from a combination of genetic, brain chemistry, and environmental factors.
Schizophrenia undoubtedly has a genetic component. The risk for inheriting schizophrenia ranges from about 10% for those who have one first-degree family member (mother, father, sister, brother) with the disease to about 40 - 65% if the disease affects both parents or an identical twin.
However, heredity does not explain all cases of schizophrenia. About 60% of people with schizophrenia have no close relatives with the illness. Researchers are seeking the specific genetic factors that may be responsible for schizophrenia. Genes under investigation include the neuregulin-1 gene, the OLIG2 gene, and the COMT gene. There is also evidence that schizophrenia may share genetic pathways with other psychotic and psychiatric disorders, such as bipolar disorder and autism.
Brain Chemistry and Structure
Brain Chemistry. Schizophrenia is associated with an unusual imbalance of neurotransmitters (chemicals that act as messengers between nerve cells). In particular, brain chemicals such as dopamine and glutamine may be involved.
Brain Structure. Magnetic resonance imaging (MRI) scans of the brains of patients with schizophrenia have revealed structural abnormalities. Such problems may cause nerve damage and disconnections in the pathways that carry brain chemicals.