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Biology 202
2002 First Paper
On Serendip


Caitlin O'Keefe

It is a frightening disorder that strikes about one percent of the world population. It surfaces most frequently during puberty and has the potential to forever destroy the lives of the people who are unfortunate enough to be its victim. The disorder is schizophrenia and it manifests itself by disturbing normal psychiatric behavior. The symptoms of schizophrenia are characterized by both positive and negative symptoms. Positive symptoms include hallucinations, delusions, and other unusual or disorganized behavior. Unresponsiveness, lack of activity, and loss of interest characterize negative symptoms. Though it is possible for doctors to diagnose and treat patients with schizophrenia, the causes of schizophrenia are still unknown. Much research has been done to further the understanding of the disorder, yet it seems that the causes of schizophrenia are still under debate. (1)

According to recent research there are several things that can cause schizophrenia. Genetic makeup among individuals affected by the disorder seems to be a significant factor. The probability of an offspring with two unaffected parents developing schizophrenia is only one percent, yet this probability increases to thirteen percent among people with one affected parent. Offspring that have two schizophrenic parents have a 35 percent chance of developing the disorder. (1)

The environment surrounding an individual also can trigger the onset of schizophrenia. It has been observed that family stress, trauma, and poor social interactions all have the tendency to promote schizophrenic behavior, though it does not necessarily cause it. Going along with this, it is also possible that prenatal conditions affect the development of schizophrenia in offspring. Viral infections, malnutrition, and birth complications have been cited as other possible causes of schizophrenia. (4)

Perhaps what is most convincing, though, are the recent links made between schizophrenia and chemical imbalances in the brain. There are four main hypotheses that support the theory that biological chemistry is responsible for causing schizophrenia. The first is named the Membrane Hypothesis. Observations of persons suffering from schizophrenia suggest that a defect or impairment in nerve cell membranes could affect how neurotransmitter receptors send messages across the nerve synapses. Also, there is evidence of decreased enzymes and fatty acids among schizophrenics. (2)

A second hypothesis is the Single-Carbon Hypothesis. This theory explains that the single-carbon folate serves as a metabolic pathway for several reactions in the brain. One of these reactions is the synthesis of methionine. It has been found that methionine metabolism is defective in many sufferers of schizophrenia. This suggests that folate is somehow related to the disorder, though exact relationship remains unknown. (2)

The NDMA Receptor Hypothesis is another suspect in the search for the cause of schizophrenia. According to research, it is possible that NDMA receptor dysfunction may induce schizophrenic symptoms due to the fact that NDMA receptors operate with glutamate, an excitatory neurotransmitter. Drugs that affect NDMA receptors, such as ketamine and phencyclidine, have been found to produce hallucinations. Also, neuroleptic drugs like clozapoine have the ability to prevent hallucinations, therefore providing further evidence to support this theory. (2)

A final hypothesis is the Dopamine Hypothesis. By far it is the most supported of all the hypotheses in the modern scientific field of neurobiology. Dopamine is a neurotransmitter in the brain that allows nerve cells to send messages to one another in order to control certain behaviors. It has been hypothesized that there is an increased level of dopamine in the brains of schizophrenics, therefore causing mainly positive symptoms such as delusions and hallucinations. Though the exact relationship between dopamine receptors and the drugs that curb schizophrenic symptoms remain unknown, studies have shown that the best drugs to treat schizophrenia are ones that block excess amounts of dopamine from being produced in the brain. Therefore, neurobiologists suspect that dopamine plays an essential role in the causes of schizophrenia. (3)

After researching schizophrenia, it is apparent that there is no clear answer to the question of what causes the psychiatric disorder. Rather, there is much debate about the four hypotheses that seem to dominate the scientific community as of late. Many researchers believe that schizophrenia may be a combination of all or some of the hypotheses. Whether these hypotheses are true or not, it is important that more research be done to become less wrong in the understanding of schizophrenia.


1)"An Introduction to Schizophrenia",

2)"Ask the Experts",

3)"The Role of Dopamine Receptors in Schizophrenia",


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