Psychologists are not 100% certain what causes schizophrenia, but most believe that there are a number of different factors that contribute towards what is a complex and serious mental health disorder. Some risk factors you can do nothing about, but others, for example stress, you can avoid if you believe you might be at risk of developing schizophrenia.
What causes schizophrenia?
The causes of schizophrenia fall into two main categories: biological and environmental. Some people are at risk of developing the disorder because of their genes, but they might never show any symptoms of schizophrenia, whereas others have no risky genes, but still develop the disorder later in life. So it is apparent that biology is not enough—social and environmental factors are also significant in the development of schizophrenia.
Genetics are known to play a significant role in the development of schizophrenia. Anyone who has a close relative with serious psychiatric disorders such as bipolar and depression has a much higher risk of developing schizophrenia than the rest of the general population. However, there are more factors at play than a genetic predisposition because statistics have shown that even when one identical twin has schizophrenia, the other twin still only has a 50% risk of developing the disorder.
A complicated birth can increase the risk of schizophrenia in later life and people who are exposed to neonatal and birth complications are more likely to go on to have schizophrenia. Risk factors include maternal pre-eclampsia, exposure to infections whilst in the womb, and oxygen deprivation during the birth.
Abnormal brain development has been linked to the development of schizophrenia and research has indicated that people who have schizophrenia often have slightly different brain structures when compared to those who do not have the disorder. Schizophrenia has also been associated with abnormal levels of dopamine and serotonin in the brain and research has suggested that the illness could in part be caused by a neurotransmitter imbalance.
Some viral infections are thought to be a factor in the development of schizophrenia. The flu virus and polio virus have both been linked to an increased risk of schizophrenia. Exposure to rubella and viral infections of the central nervous system can also increase the schizophrenia risk factor.
Serious head injuries can sometimes cause schizophrenia later in life—although scientists are not sure why this is the case and it could be that the head injury triggers schizophrenia in someone who is already genetically predisposed to developing the disorder anyway.
Other causes of schizophrenia
Substance abuse is known to trigger many mental health problems, including schizophrenia. This is especially true of long term cannabis users, and if a teenager is a habitual user of the drug, they are much more at risk of developing schizophrenia, particularly if there is a history of mental illness in their family.
Being exposed to a dysfunctional childhood and extreme stress can also cause schizophrenia in those already predisposed towards the illness—one research study showed that adopted children with a higher genetic risk of schizophrenia were much more likely to develop the disorder if raised in a dysfunctional family environment.