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Abstract Schizophrenia is a severe mental disorder characterized by profound disruption in cognition and perception, inadequate emotionality and impaired ability to behave properly. Contrary to popular belief, schizophrenia is not a split or multiple personality. Schizophrenia is a psychosis, a type of mental illness in which a person cannot tell what is real from what is imagined. Schizophrenia is characterized by positive and negative symptoms that can influence a patient’s thoughts, perceptions, speech, affect, and behaviors. Positive symptoms include hallucinations, voices that converse with or about the patient, and delusions that are often paranoid. Negative symptoms include flattened affect, loss of a sense of pleasure, loss of will or drive, and social withdrawal. In patients with the schizophrenia, magnetic resonance imaging has shown a reduction in volume of some brain structures (amygdala and/or hippocampus), enlargement of brain ventricles as well as a loss of white matter. Neurotransmitter systems and intracellular signal transduction are impaired especially dopamine system. Dopamine (DA) is a catecholamine neurotransmitter that is linked to the pathophysiology of schizophrenia. It has a role in pleasure, mood, behavior, cognition, motivation, creativity and reward. The “original dopamine hypothesis” states that hyperactive dopamine transmission results in schizophrenic symptoms. On target areas, Dopamine acts through five dopamine receptors, which belong to the superfamily of seven-transmembrane G protei |