By comparison, the risk of schizophrenia in the general population is about 1 percent. As scientists study the association between schizophrenia and genetic factors, it appears that multiple genes are involved in creating a tendency to develop the disorder. Factors such as prenatal difficulties like intrauterine starvation or viral infections, prenatal complications, and various nonspecific stressors, seem to influence the development of schizophrenia. It still is not understood how the genetic predisposition is transmitted, and is unable to accurately predict whether a given person will or will not develop the disorder. Identification of specific genes involved in the development of schizophrenia will provide important clues into what goes wrong in the brain to produce and sustain the illness and will guide the development of new and better treatments; however researchers are still trying to figure out which genes will help to discover schizophrenia. (sfnat).
Brain chemistry can also play a major role in the cause of schizophrenia. Neurotransmitters have always been thought to be involved in the development of schizophrenia. It has not yet been proven, but is highly likely that the disorder is associated with some imbalance of the complex, interrelated chemical systems of the brain, possibly involving the neurotransmitters dopamine and glutamate. Enlargement of the fluid-filled cavities, or ventricles in the interior of the brain, and decreased size of certain brain regions are abnormalities in the brain structure that may be able to cause schizophrenia. (nimh).
Although there is no single symptom of schizophrenia there are many different symptoms of this disease. Many people with schizophrenia develop delusions, unusual or steadfast beliefs. Sometimes it will go as far as to believing that they have special powers, and most are very paranoid, always thinking that someone is watching or spying on them.