Scientists don't know what causes schizophrenia, but most likely it develops out of both genetic and environmental factors. Relatives of people with schizophrenia are more likely to develop it. For instance, you have a 10 percent chance of developing the disorder if you have a first degree relative (such as a parent or sibling) with schizophrenia (as opposed to a 1 percent chance in the general population) [source: NIMH]. In addition, an identical twin of a schizophrenic has a 40 percent to 65 percent chance of developing it [source: NIMH]. Although statistics indicate that genetics certainly have something to do with it, they do not tell the whole story. Merely looking at genetic makeup cannot help scientists definitively determine who will develop the disorder. It is possible that several different genes play various parts in schizophrenia, and other factors contribute as well.
If you are genetically predisposed to the disorder, environmental factors could contribute to your chances of developing it. Some of these factors go back even before birth. For example, one study suggests that if a mother gets sick with the flu during pregnancy, this can increase the risk of the child developing schizophrenia [source: Minkel]. In addition, complications during birth, malnutrition and brain injuries also might increase someone's chances of getting it.
Some studies reveal possible causes for the specific symptoms of schizophrenia. For instance, the hallucinations that many schizophrenics experience might stem from the individual's disconnect from reality. If their ideas are split off from their actual sensations or feelings, they might not be able to predict their own behavior [source: Zimmer]. In this way, if they fail to predict their own inner voice, they might come to the conclusion that it did not come from themselves. In addition, this could explain why many believe someone else is controlling their behavior.
Scientists also look for answers by studying the chemical makeup of the brain for people with schizophrenia. The medications that treat schizophrenia offer just as many questions as answers about how brain functions play a part in the disorder. Based on the effects of different drugs, researchers now believe the neurotransmitters dopamine and glutamate play major roles in schizophrenia. Next, in the treatments section, we'll discuss how helpful medications affect these neurotransmitters.