Theories on the Causes of Schizophrenia
At this point, researchers do not know the exact causes of
schizophrenia. However, as is the case for many other illnesses, the cause is believed to involve a combination of environmental and genetic factors.
How Genes Contribute to Schizophrenia
While genetics do not specifically cause schizophrenia, genes are thought to play a role in a person's risk of developing it.
Scientists have long known that schizophrenia runs in families. It occurs in 1 percent of the general population, but is seen in 10 percent of people with a first-degree relative (a parent, brother, or sister) with schizophrenia. People who have second-degree relatives (aunts, uncles, grandparents, or cousins) with the disease also develop schizophrenia more often than the general population. The identical twin of a person with schizophrenia is most at risk, having a 40 to 65 percent chance of developing the condition.
Our genes are located on 23 pairs of chromosomes that are found in each cell. We inherit two copies of each gene -- one from each parent. Several of these genes are thought to be associated with an increased risk of schizophrenia, but scientists currently believe that each gene has a small effect and that no single gene is the cause of schizophrenia by itself. It is still not possible to predict who will develop the disease simply by looking at a person's genetic material.
So, although there is a genetic risk for the disorder, genes are unlikely to cause schizophrenia on their own. It is believed that interactions between genes and the environment are necessary for the development of schizophrenia.
