The Dopamine Hypothesis of Schizophrenia

The Dopamine Hypothesis of Schizophrenia

Schizophrenia is a disease that has plagued societies around the world for centuries, although it was not given its formal name until 1911. It is characterized by the presence of positive and negative symptoms. Positive symptoms are so named because of the presence of altered behaviors, such as delusions, hallucinations (usually auditory), extreme emotions, excited motor activity, and incoherent thoughts and speech. (1,2) In contrast, negative symptoms are described as a lack of behaviors, such as emotion, speech, social interaction, and action. (1,2) These symptoms are by no means concrete. Not all schizophrenic patients will exhibit all or even a majority of these symptoms, and there is some disagreement in the psychiatric community as to the exact diagnostic criteria. In addition, there is a great deal of debate as to the causes of the disease. While some proposed causes have been proven false, such as bad parenting and poor will power (2), there are many theories that remain. One of the most famous and most debatable is the dopamine hypothesis. The proposed hypothesis states that the brain of schizophrenic patients produces more dopamine than normal brains. It is this increased dopamine that is believed to be responsible for the symptoms of the disease. However, the is much debate in the scientific community as to the exact mechanism by which altered dopamine levels, especially in the prefrontal cortex, striatum, and limbic system, produce schizophrenia. There is much clinical evidense that provides support for the dopamine hypothesis. The first evidense that dopamine may be involved in schizophrenia came from amphetamine users. Amphetamines work by causing the brain to produce mo...

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