Neurochemistry of Schizophrenia: The Contribution of Neuroimaging Postmortem Pathology and Neurochemistry in Schizophrenia

The advent of molecular neuroimaging has greatly impacted on understanding the neurochemical changes occurring in the CNS from subjects with psychiatric disorders, especially schizophrenia. This review focuses on the outcomes from studies using positron emission tomography and single photon emission computer tomography that have measure levels of neurotransmitter receptors and transporters in the CNS from subjects with schizophrenia. One outcome from such studies is the confirmation of a number of findings using postmortem tissue, but in the case of neuroimaging, using drug nave and drug free subjects. These findings add weight to the argument that findings from postmortem studies are not an artifact of tissue processing or a simple drug effect. However, there are some important unique findings from studies using neuroimaging studies. These include evidence to suggest that in schizophrenia there are alterations in dopamine synthesis and release, which are not accompanied by an appropriate down-regulation of dopamine D2 receptors. There are also data that would support the notion that decreased levels of serotonin 2A receptors may be an early marker of the onset of schizophrenia. Whilst there is a clear need for on-going development of neuroimaging ligands to expand the number of targets that can be studied and to increase cohort sizes in neuroimaging studies to give power to the analyses of the resulting data, current studies show that existing neuroimaging studies have already extended our understanding of the underlying pathophysiology of psychiatric disorders such as schizophrenia.