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Biology 202
2003 Second Web Paper
On Serendip

The Effects of Schizophrenia on the Brain

Adina Cazaban

Schizophrenia is a severe mental illness that affects one to two percent of people worldwide. The disorder can develop as early as the age of five, though it is very rare at such an early age. (3)) Most men become ill between the ages of 16 and 25 whereas most women become ill between the ages of 25 and 30. Even though there are differences in the age of development between the sexes, men and women are equally at risk for schizophrenia. (4) There is of yet no definitive answer as to what causes the disorder. It is believed to be a combination of factors including genetic make-up, pre-natal viruses, and early brain damage which cause neurotransmitter problems in the brain. (3)

These problems cause the symptoms of schizophrenia, which include hallucinations, delusions, disordered thinking, and unusual speech or behavior. No "cure" has yet been discovered, although many different methods have been tried. Even in these modern times, only one in five affected people fully recovers. (4) The most common treatment is the administration of antipsychotic drugs. Other treatments that were previously used, and are occasionally still given are electro-convulsive therapy, which runs a small amount of electric current through the brain and causes seizures, and large doses of Vitamin B. (3)

Due to neurological studies of the brain, antipsychotic drugs have become the most widely used treatments. These studies show that there are widespread abnormalities in the structural connectivity of the brains of affected people. (2) It was noticed that in brains affected with schizophrenia, far more neurotransmitters are released between neurons, which is what causes the symptoms. At first, researchers thought that the problem was solely caused by excesses of dopamine in the brain. However, newer studies indicate that the neurotransmitter serotonin also plays a role in causing the symptoms. This was discovered when tests indicated that many patients better results with medications that affect the serotonin as well as the dopamine transmissions in the brain. (6)

New test and machines also enabled researchers to study the structure of schizophrenic brains using Magnetic Resonance Imagery (MRI) and Magnetic Resonance Spectroscopy (MRS). The different lobes of affected brains were examined and compared to those of normal brains, showing several structural differences. The most common finding was the enlargement of the lateral ventricles, which are the fluid-filled sacs that surround the brain. The other differences, however, are not nearly as universal, though they are significant. There is some evidence that the volume of the brain is reduced and that the cerebral cortex is smaller. (2)

Tests showed that blood flow was lower in frontal regions in afflicted people when compared to non-afflicted people. This condition has become known as hypofrontality. Other studies illustrate that people with schizophrenia often show reduced activation in frontal regions of the brain during tasks known to normally activate them. (1) Even though many tests show that the frontal lobe function performance is impaired and although there is evidence of reduced volume of some frontal lobe regions, no consistent pattern of structural degradation has yet been found. (2)

There is, however, a great deal of evidence that shows that the temporal lobe structures in schizophrenic patients are smaller. Some studies have found the hippocampus and amygdala to be reduced in volume. Also, components of the limbic system, which is involved in the control of mood and emotion, and regions of the Superior Temporal Gyrus (STG), which is a large contributor in language function, have been notably smaller. The Heschl's Gyrus (which contains the primary auditory cortex), and the Planum Temporale are diminished. The severity of symptoms such as auditory hallucinations has been found to be dependent upon the sizes of these language areas. (2)

Another area of the brain that has been found to be severely affected is the prefrontal cortex. The prefrontal cortex is associated with memory, which would explain the disordered thought processes found in schizophrenics. Test done on humans and animals in which the prefrontal cortex has been damaged showed similar cognitive problems as those seen in schizophrenic patients. The prefrontal cortex has one of the highest concentrations of nerve fibers with the neurotransmitter dopamine and scientists have learned that the relatively new antipsychotic drug, which increases the amount of dopamine released in the prefrontal cortex, often improves cognitive symptoms. They also found that the prefrontal cortex contains a high concentration of dopamine receptors that interact with glutamate receptors to enable neurons to form memories. This means that dopamine receptors may be especially important for reducing cognitive symptoms. (5)

While these drugs do help control the symptoms of schizophrenia, they do not get rid of the disorder. It is becoming clearer ever day, just what damage schizophrenia is doing to the brain, but researchers are nowhere near to finding all of the answers. Different researchers are still arguing over the conclusiveness of the data that does exist. Other scientists are trying to discover the cause of schizophrenia. Is it caused by various genes, by a virus, or from trauma? This too is still a mystery. The only thing that is truly known is that the disorder is debilitating and that it affects nearly every portion of the brain. Obviously, much more research still needs to be done to help those who suffer from it.


References

1)E-Mental Health,

2) E-Mental Health,

3)National Institute for Mental Health,

4)Psychiatry 24 x 7,

5) Society of Neuroscience,


6)Health-Center,


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