The exact cause of schizophrenia is not currently known, and it is thought to occur as a result of various genetic, physical, psychological and environmental risk factors.
In this way, some people are more likely to be affected by the condition due to genetic and physical susceptibility but a particular life event, usually stressful or emotional in nature, triggers the condition.
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Genetic Factors
Although it is well known that schizophrenia tends to run in families and is likely to be inherited from parents that carry a certain gene, there is no gene that has been linked to an increased risk of schizophrenia.
For this reason, many medical researchers believe that a combination of genes increases the risk of an individual for developing the condition. However, not everyone with the genetic makeup will become affected by schizophrenia, as it is also dependent on other risk factors.
Studies of identical twins that share the same genes have enabled genetic research about schizophrenia to become a reality. It has been observed that if one twin develops schizophrenia, the other twin has a 50% chance of developing the condition. This is in contrast to non-identical twins, who have a one in seven chance of developing the condition if the other twin is affected.
Brain Involvement
It has been observed that there are subtle changes in the physical structure of the brain of people affected by schizophrenia. However, these changes aren’t uniformly present in people with the condition and may exist in people that are not symptomatic.
Additionally, the neurotransmitters responsible for carrying messages in the brain may also be involved. This has been suggested due to the efficacy of medications that alter neurotransmitters in the brain in the treatment of schizophrenia. In particular, dopamine and serotonin are thought to be linked to the development of the condition and some research suggests it is an imbalance of these two neurotransmitters that is problematic.
Complications at Infancy
Individuals that were subjected to complications before and during birth have also been observed to be at greater risk of developing schizophrenia. These complications may include premature labor, low birth weight and asphyxia during birth. Additionally, exposure to viruses or infections in the womb or early infancy may also have an effect.
The pathophysiology of this link is not known for certain, although it is thought to be a result of subtle changes in the development of the infant’s brain.
Environmental Triggers
There are certain situations that tend to cause the development of schizophrenia in those people that are at risk of the condition due to genetic and physical factors.
Stressful life events are the most common trigger for schizophrenia. The nature of the event can vary greatly and may include sudden job loss, divorce or abuse but any stressful event has the potential to trigger a psychotic episode in a susceptible individual.
Additionally, misuse of drugs has also been linked to an increased risk of schizophrenia. Common drugs that have triggered the onset of the condition include cannabis, cocaine, LSD and amphetamines.
Environmental triggers are almost always associated with the development of schizophrenia, but it is worth noting that they are not sufficient to cause the condition alone. Many individuals experience similarly stressful events throughout their life without developing schizophrenia and the predetermined susceptibility is, therefore, of particular importance.
References
Common brain network connected to heterogeneous patterns of brain atrophy in schizophrenia