No one single cause has yet been attributed to schizophrenia. Rather, it appears that several factors may play a role in the onset of the illness. The causes of schizophrenia, like many other illnesses, are likely to be a combination of hereditary and environmental factors. The vulnerability-stress model of schizophrenia states that there is an interaction between the person’s biological vulnerability, stress or change in the environment and their ability to deal with these environmental factors in terms of their social skills and supports.
There is now a huge amount of research being conducted into the possible causes of schizophrenia; the most prominent theories are stated below. One thing we do know for certain is that bad parenting; poverty or sinful behaviour does not cause schizophrenia.
Genes
Twin, family and adoption studies suggest that genetic factors play an important role in the development of schizophrenia. For example, the child of one parent with schizophrenia has about a 10 % risk of developing schizophrenia; if both parents have schizophrenia the risk is increased to 40%. By comparison, the risk of schizophrenia in the general population is about 1%.
Environment
Possible environmental factors include complications during pregnancy and at birth. It has also been suggested that stress and trauma can lead to the emergence of schizophrenia. There is no evidence that families cause schizophrenia, however, positive relationships within the family can play an important role in preventing future episodes.
Biochemical
Certain biochemical imbalances in the brain are believed to be involved in causing the symptoms of schizophrenia. Neurotransmitters (the substances that allow communication between nerve cells) such as dopamine and serotonin, have long been thought to be involved in the development of the symptoms seen in people with schizophrenia.
Drug Misuse
Illegal drugs such as LSD, cocaine, speed and marijuana are known to mimic the psychotic symptoms of schizophrenia in some people. Although contentious, some research suggests that substance misuse can also be related to the development of schizophrenia. It is likely that substance misuse may worsen the symptoms and interfere in the treatment of a person with schizophrenia.
