Physical changes in the brain have been identified in some people with schizophrenia. The analysis of brain tissue after death has revealed a number of structural abnormalities, and new brain-imaging techniques have revealed changes in both the structure and function of the brain during life. Techniques such as magnetic resonance imaging (MRI) reveal changes in the size of different parts of the brain, especially in the temporal lobes. The fluid-filled spaces (the ventricles) in the interior of the temporal lobes are often enlarged and the temporal lobe tissue diminished. The greater the observed changes the greater the severity of the person’s thought disorder and his or her auditory hallucinations. Show
Some imaging techniques, such as positron emission tomography (PET), measure the actual functioning of the brain and provide a similar picture of abnormality. PET scanning reveals hyperactivity in the temporal lobes, particularly in the hippocampus, a part of the temporal lobe concerned with orientation and very short-term memory. Another type of functional imaging, electrophysiological brain recording using EEG tracings, shows that most people with schizophrenia seem to be excessively responsive to repeated environmental stimuli and more limited in their ability to blot out irrelevant information. In line with this finding, those parts of the brain that are supposed to screen out irrelevant stimuli, such as the frontal lobe, show decreased activity on PET scan. Tying in with this sensory screening difficulty, post-mortem brain tissue examination has revealed problems in a certain type of brain cell? the inhibitory interneuron. These neurons damp down the action of the principal nerve cells, preventing them from responding to too many inputs. Thus, they prevent the brain from being overwhelmed by too much sensory information from the environment. The chemical messengers or neurotransmitters (primarily gamma-amino butyric acid or GABA) released by these interneurons are diminished in the brains of people with schizophrenia, suggesting that there is less inhibition of brain overload. Abnormality in the functioning of these interneurons appears to produce changes in the brain cells which release the neurotransmitter dopamine. The role of dopamine has long been of interest to schizophrenia researchers, because drugs such as amphetamines that increase dopamine’s effects can cause psychoses that resemble schizophrenia, and drugs that block or decrease dopamine’s effect are useful for the treatment of psychoses. Dopamine increases the sensitivity of brain cells to stimuli. Ordinarily, this heightened awareness is useful in increasing a person’s awareness during times of stress or danger, but, for a person with schizophrenia, the addition the effect of dopamine to an already hyperactive brain state may tip the person into psychosis. These findings suggest that in schizophrenia there is a deficit in the regulation of brain activity by interneurons, so that the brain over-responds to the many signals in the environment and lacks the ability to screen out unwanted stimuli. This problem is made worse by a decrease in the size of the temporal lobes, which ordinarily process sensory inputs, making it more difficult for the person to respond appropriately to new stimuli. The exact causes of schizophrenia are unknown. Research suggests a combination of physical, genetic, psychological and environmental factors can make a person more likely to develop the condition. Some people may be prone to schizophrenia, and a stressful or emotional life event might trigger a psychotic episode. However, it's not known why some people develop symptoms while others do not. Schizophrenia tends to run in families, but no single gene is thought to be responsible. It's more likely that different combinations of genes make people more vulnerable to the condition. However, having these genes does not necessarily mean you'll develop schizophrenia. Evidence that the disorder is partly inherited
comes from studies of twins. Identical twins share the same genes. In identical twins, if a twin develops schizophrenia, the other twin has a 1 in 2 chance of developing it, too. This is true even if they're raised separately. In non-identical twins, who have different genetic make-ups, when a twin develops schizophrenia, the other only has a 1 in 8 chance of developing the condition. While this is higher than in the general population, where the chance is about 1 in 100, it suggests genes are not the only factor influencing the development of schizophrenia. Brain developmentStudies of people with schizophrenia have shown there are subtle differences in the structure of their brains. These changes are not seen in everyone with schizophrenia and can occur in people who do not have a mental illness. But they suggest schizophrenia may partly be a disorder of the brain. NeurotransmittersNeurotransmitters are chemicals that carry messages between brain cells. There's a connection between neurotransmitters and schizophrenia because drugs that alter the levels of neurotransmitters in the brain are known to relieve some of the symptoms of schizophrenia. Research suggests schizophrenia may be caused by a change in the level of 2 neurotransmitters: dopamine and serotonin. Some studies indicate an imbalance between the 2 may be the basis of the problem. Others have found a change in the body's sensitivity to the neurotransmitters is part of the cause of schizophrenia. Pregnancy and birth complicationsResearch has shown people who develop schizophrenia are more likely to have experienced complications before and during their birth, such as:
It may be that these things have a subtle effect on brain development. TriggersTriggers are things that can cause schizophrenia to develop in people who are at risk. These include: StressThe main psychological triggers of schizophrenia are stressful life events, such as:
These kinds of experiences, although stressful, do not cause schizophrenia. However, they can trigger its development in someone already vulnerable to it. Drug abuseDrugs do not directly cause schizophrenia, but studies have shown drug misuse increases the risk of developing schizophrenia or a similar illness. Certain drugs, particularly cannabis, cocaine, LSD or amphetamines, may trigger symptoms of schizophrenia in people who are susceptible. Using amphetamines or cocaine can lead to psychosis, and can cause a relapse in people recovering from an earlier episode. Research has shown that teenagers and young adults who use cannabis regularly are more likely to develop schizophrenia in later adulthood. Want to know more?
What brain structures are involved in schizophrenia?Schizophrenia is associated with changes in the structure and functioning of a number of key brain systems, including prefrontal and medial temporal lobe regions involved in working memory and declarative memory, respectively.
What happens to the brain when someone has schizophrenia?In schizophrenia, dopamine is tied to hallucinations and delusions. That's because brain areas that "run" on dopamine may become overactive. Antipsychotic drugs stop this. Glutamate is a chemical involved in the part of the brain that forms memories and helps us learn new things.
What parts of the brain are smaller in people with schizophrenia?The cerebellum is among the most affected brain regions in schizophrenia, new research has found. Compared to healthy individuals, cerebellar volume was smaller in patients with schizophrenia.
What part of the brain is positive in schizophrenia?Hippocampal function
The metabolism and blood flow of the hippocampus are increased at baseline in schizophrenia. Furthermore, hippocampal and parahippocampal rCBF is increased during the experience of psychotic symptoms and correlates with positive symptoms (delusions, hallucinations).
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Which of the following statements is true of the brain structure in a person with schizophrenia
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