Schizophrenia is a class of disorders that are marked by disturbances of perception, cognition, emotions and motor behaviors. According to 2010 information from the National Institutes of Health, approximately 2.2 million Americans suffer from this illness, which has no known cure. Numerous theories exist about the causes of schizophrenia, ranging from viruses to genetics, and from life circumstances to biochemistry. One cause alone is unlikely, but it seems that biochemistry plays an essential role in is occurrence.
Too Much Dopamine
According to the first version of Dopamine Hypothesis of Schizophrenia, written by Dr. J. Van Rossum in 1967, the use of large amounts of amphetamine or LSD can lead to an amphetamine psychosis that includes hallucinations, delusions and other symptoms that resemble those seen in schizophrenic patients. Both of these drugs increase the stimulation of dopamine synapses. Dopamine is a neurotransmitter, or a messenger, that is associated with reward and reinforcement. All neurotransmitters help to send messages from themselves to another neuron. Dr. Van Rossum's hypothesis states that schizophrenia is caused by excess amount of dopamine synapses.
Too Many Dopamine Receptors
Soon after the Dopamine Hypothesis was introduced, new findings were quickly published. When dopamine and its metabolites were directly measured from the blood, or in the cerebrospinal fluid by Dr. Bacopoulous, it was found that many schizophrenics had normal levels of dopamine. Although some showed elevated levels of it, the difference compared to healthy controls was not significant. These findings were published in "Science" in 1979. Thus, it was concluded that schizophrenics may have increased numbers of dopamine receptors that react to the neuron. This hypothesis was verified by Dr. Seeman in "Science" in 1984, when he showed in an autopsy study that there was a substantial increase in the number of dopamine receptors in the brains of schizophrenics. Whether this increase is due to the illness or prolonged use of drugs is an area of widely differing opinions in the scientific community.
Schizophrenia and Glutamate
Glutamate is a neurotransmitter that plays a crucial role in learning and memory. Some drugs, such as PCP given to surgical patients, are known to block glutamate receptors and can cause paranoia that resembles schizophrenic symptoms. Dr. J.S. Kim was among the first scientists who reported in "Neuroscience Letters" in 1980 that schizophrenics have reduced levels of glutamate in their cerebrospinal fluid. This idea later became known as a "glutamate hypothesis."
References
- National Institute of Mental Health: Schizophrenia
- "Neuropsychopharmacology, Proceedings Fifth Collegium Internationale Neuropsychopharmacologicum"; Rossum; 1979
- "Science"; Antipsychotic drug action in schizophrenic patients: Effect on cortical dopamine metabolism after long-term treatment; Bacopoulous; vol. 205, 1405-1407, 1979
- "Science"; Bimodal distribution of dopamine receptor densities in brains of schizophrenics.; Seeman, vol. 225, 728-732, 1984
- "Neuroscience Letter"; Low cerebrospinal fluid glutamate in schizophrenic patients and a new hypothesis on schizophrenia.; Kim, Kornhuber, Schmid-Burgk; vol. 20, 379-382, 1980
