Dopamine

Schizophrenia is a form of psychosis or loss of contact with reality. It is estimated to affect about 1% of the population, or over 2.5 million Americans. A great deal of research is being done on the origins of schizophrenia. One widely accepted theory is that it is caused by an excess of dopamine or dopamine receptors. Receptors are proteins on the surfaces of cells that act as signal acceptors for the cells. They allow cells to send information, usually through neurotransmitter molecules. This hypersensitivity to dopamine (the prefix "hyper" means over or excessive) is treated by using chemicals that block (or inactivate) the receptors for the dopamine signals. However, there are a number of different types of dopamine receptors and there are many differences among individuals in the structures of these receptors. Drugs usually block all of the receptors, not just the ones related to schizophrenic symptoms, resulting in many side effects. Other approaches to the treatment of schizophrenia have focused on decreasing the amounts of dopamine in the brain. In doing so, however, symptoms of Parkinson disease often result, since less dopamine (or the ability to respond to dopamine) is present. The origins of schizophrenia are unclear; dopamine excess is probably not the sole cause of the disease as strong evidence for genetic and environmental factors exists as well. To date, treatments that focus on excess dopamine sensitivity have been the most successful.