Schizophrenia is a psychological disorder in which a patient experiences symptoms including hallucinations, delusions, amotivation, social withdrawal, cognitive defects, and poor working memory. Heredity and gene inheritance is a highly important risk factor, especially for identical twins. Schizophrenia is anatomically characterized by a deterioration and loss of gray matter in the temporal and frontal regions of the cerebral cortex, though the exact mechanism is unknown. What is known is that the main two neurotransmitter systems implicated in schizophrenia are the dopamine and glutamate pathways.
Dopamine became a candidate for research when it was clinically noticed that antipsychotic drugs which are dopamine D receptor antagonists were noted to be quite successful in treating schizophrenia as well. Increased levels of dopamine in people with schizophrenia tend to induce paranoid delusions, ideas of reference, and auditory hallucinations. The same dopaminergic pathway is also involved in psychosis.
Glutamate has become a candidate for treatment focus because glutamate blocks some NMDA receptors which, on their own, induce schizophrenic behavior. In animal models, NMDA antagonists increase glutamate release in the prefrontal cortex. It is postulated that this is a homeostatic response to NMDA receptor blockade, which in turn increases psychotic symptoms. A class of NMDA receptor antagonists have been denoted dissociative anesthetics because they produce a sense of depersonalization and dissociation of subjective experience from various forms of sensory input stimuli. As such, variants such as Ketamine (Angel Dust/Special K) and Phencyclidine (PCP) have become a commonly abused street-drug. These drugs are no longer used due to harmful behavioral and addictive effects.