From research, it has been clear that there is no single known cause for schizophrenia. Many other diseases like heart disease is caused by interaction between many factors like genetic, behavioral, etc and schizophrenia also comes under this category.
It has known since long that schizophrenia is a genetically inherited disease and runs in families. Persons with close relatives affected with schizophrenia are generally more likely to get schizophrenia than people with no relatives with schizophrenia at all. A good example is that a person is 40-50% more likely to develop schizophrenia when he has an identical twin affected with schizophrenia. And another illustration is that a child is 10% more likely to get schizophrenia when his parent is affected with schizophrenia. And the risk is just 1% in the normal population to develop schizophrenia.
Research is being conducted for identifying the genetic factors which is responsible for schizophrenia. It has been found that several genes are responsible for the development of the disorder. Besides, factors like prenatal difficulties involving viral infections or intrauterine starvation, perinatal complications, etc. There are some nonspecific stressors which act as triggers. But yet the genetic transmission of the disease has not been identified accurately and hence it is impossible to say if a person will develop schizophrenia or not.
Various combinations of the human genome are being investigated to identify those involved in schizophrenia. Recent research has proved that chromosomes 13 and 6 may be responsible but not yet certain. When the actual genes are identified exactly, it can help the doctors to better treat schizophrenic patients. Schizophrenia Genetics Initiative has been established by NIMH (National Institute of Mental Health) which is currently gathering data from large number of affected people to identify the genes and develop a new treatment mode.
Research was conducted to determine whether Schizophrenia is caused by a chemical defect occurring in the brain. The basic knowledge linking brain chemistry with Schizophrenia is investigated in depth. Neurotransmitters are also doubted to be concerned in causing Schizophrenia or it may also be caused by some imbalance in the release of neurotransmitters, especially the dopamine and glutamate. It seems to give a promising solution.
The next area of research includes structural abnormality of the brain. Several neuro-imaging techniques like MRI, PEST, etc are being tried upon to identify the structural differences in the brain. The Schizophrenic people are found to have enlarged ventricles and certain regions decreased in size. Sometimes the defect is with the function like decreased metabolic activity. But these reasons are subtle and are not the only cause for Schizophrenia or found only in Schizophrenic people. Schizophrenic people’s brain when examined after death shows small changes in the number and distribution of neurons as compared to normal people. But normally these changes seem to be present even before the illness occurs.
Developmental neurobiologists have found that Schizophrenia can occur as a developmental disorder occurring when brain cells form inappropriate links in the course of fetal development. Such errors though dormant in the beginning stages may show up after puberty since there are some changes occurring in the brain after maturation. Hence this has led to identification of prenatal factors.
In other researches, some brain imaging techniques have shown biochemical changes which lead to the start of the symptoms of Schizophrenia. Hence this has led to investigation regarding the neural circuits involved in producing the symptoms.