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Schizophrenia

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  • Genetic predisposition: Substantial evidence suggests that there is a genetically inherited predisposition to schizophrenia. For example, there is a concordance rate of about 48 percent for identical twins. The concordance rate for fraternal twins is considerably less, about 17 percent. Concordance rate refers to the percentage of both people in a pair having a certain trait or disorder. A person who has two parents with schizophrenia has about a 46 percent chance of developing schizophrenia. This probability is very high compared to the roughly 1 percent chance of developing schizophrenia in the general population.
  • Neurotransmitters: Some researchers have proposed that schizophrenia is related to an overabundance of the neurotransmitter dopamine in the brain. Other researchers have suggested that both serotonin and dopamine may be implicated. The neurotransmitter glutamate may also play a role in the disorder. Underdevelopment of glutamate neurons results in the overactivity of dopamine neurons.
  • Brain structure: Some researchers have suggested that schizophrenia may involve an inability to filter out irrelevant information, which leads to being overwhelmed by stimuli. With this idea in mind, researchers have looked for brain abnormalities in schizophrenia patients. The brains of people with schizophrenia do differ structurally from the brains of normal people in several ways. For example, they are more likely to have enlarged ventricles, or fluid-filled spaces. They are also more likely to have abnormalities in the thalamus and reduced hippocampus volume.
  • Brain injury: Another line of research suggests that injuries to the brain during sensitive periods of development can make people susceptible to schizophrenia later on in life. For example, researchers believe that viral infections or malnutrition during the prenatal period and complications during the birthing process can increase the later risk of schizophrenia. Some researchers have suggested that abnormal brain development during adolescence may also play a role in schizophrenia.
Stress

Many researchers believe stress plays a role in bringing on schizophrenia in people who are already biologically vulnerable to this disorder.