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DOI: 10.1055/s-0033-1353335
Alterations in cortical and extra-striatal sub-cortical dopamine function in schizophrenia: a systematic review and meta-analysis of imaging studies
The hypothesis that cortical dopaminergic alterations underlie aspects of schizophrenia has been highly influential. This review synthesises and evaluates the imaging evidence for dopaminergic alterations in cortical and other extra-striatal regions in schizophrenia. Electronic databases were searched for in vivo molecular studies of extra-striatal dopaminergic function in schizophrenia. Twenty-three studies including 278 patients and 265 controls were identified. The meta-analysis of dopamine D2/D3 receptor availability showed a trend for a reduction in the thalamus (d =-0.32, 95%-CI: -0.68 to 0.03) but no change in the temporal cortex (d =-0.23, 95%-CI: -0.54 to 0.07) or the substantia nigra (d = 0.04, 95%-CI: -0.92 to 0.99). Significant differences were reported for D2/3 receptors in the cingulate, and uncus; for D1 receptors in the prefrontal cortex; and for dopamine transporters in the thalamus; whilst no differences were reported in entorhinal cortex, hippocampus, amygdala, occipital cortex, parietal cortex, insula or globus pallidum. Despite the wide influence of the hypothesis, there is limited direct evidence regarding cortical dopaminergic alterations in schizophrenia. However the available data indicate there may be alterations in the thalamus and that frontal D1 receptor availability warrants further investigation.