No one understands what causes schizophrenia, as no single cause explains all cases of schizophrenia. Genetics, birth defects, environmental triggers and imbalances of the neurotransmitter dopamine are possible causes of schizophrenia symptoms.
Genetics and Causes of Schizophrenia
Identical twin studies prove that genetics play a role in schizophrenia. If one identical twin develops schizophrenia symptoms, the other twin has a 40 to 50 percent chance of developing the mental illness, according to the National Institute of Mental Health (NIMH). Studies have also shown that having a parent or sibling with schizophrenia increases a person’s schizophrenia risk to 10 percent, compared with 1 percent for the general population.
Genetic variables don’t explain all schizophrenia cases. Many people with schizophrenia have no family history of schizophrenia symptoms.
Dopamine Imbalances as Causes of Schizophrenia
Dopamine imbalances are possible causes of schizophrenia. Dopamine is a brain neurotransmitter that relays brain nerve cell impulses. Dopamine’s exact role in schizophrenia is unclear, but some researchers have observed that the brains of subjects with schizophrenia have more dopamine receptors than those of the general population.
Antipsychotic medication, the most common schizophrenia treatment, blocks the absorption of dopamine. By blocking the brain’s receptors, antipsychotic medication reduces the severity of schizophrenia symptoms.
Not all schizophrenia researchers believe dopamine imbalances are causes of schizophrenia. Antipsychotic drugs block dopamine levels very quickly, but schizophrenia symptoms don’t improve until after weeks of treatment. Antipsychotics may affect brain chemistry and improve schizophrenia symptoms in as-yet unknown ways.
Researchers skeptical of the dopamine theory note that new generations of schizophrenia medication block both serotonin and dopamine receptors, and appear to be more effective treatments for “negative” schizophrenia symptoms such as social withdrawal and deadened emotions.
Pregnancy is considered an environmental cause of schizophrenia. A blood protein incompatibility called Rh incompatibility, maternal influenza and maternal malnutrition all appear to increase the child’s schizophrenia risks.
Life stressors may trigger schizophrenia in people with genetic susceptibility to the illness. Ending relationships, leaving home and other life stressors trigger schizophrenia onset in some cases.
Brain Structure and Schizophrenia
Studies of the brain structure of persons with schizophrenia after death reveal enlarged brain ventricles, which are cavities inside the brain containing cerebrospinal fluid. Also, some brain regions are smaller than average. However, not all schizophrenia cases display these brain abnormalities, and many people who don’t suffer from schizophrenia have similar brain structures.
What Causes Schizophrenia?
Current schizophrenia theories suggest that no single cause of schizophrenia exists. New theories propose that schizophrenia genetics increase susceptibility to the disorder, which is triggered by environmental factors.
Many schizophrenia experts believe that schizophrenia is actually more than one disorder, and that schizophrenia symptoms result from several subtly different mental disorders. Determining exactly what causes and triggers schizophrenia symptoms is complicated, particularly because of the wide range of symptoms among the different types of schizophrenia.
Fauci, A., Braunwald, E., Isselbacher, K., Wilson, J., Martin, J., Kasper, D., …