Where Dopamine Signaling Is Altered in Psychosis

Blockade by neuroleptics of postsynaptic dopamine D₂ receptors led to the theory that this is the mechanism of action of these drugs. Early reports of elevated striatal D₂ receptor density in schizophrenia seemed to support this view. To determine the accuracy of these early observations, researchers conducted a meta-analysis of 44 functional neuroimaging studies that used positron emission tomography or single-photon emission computed tomography of striatal dopaminergic function in 618 schizophrenia patients and 606 healthy controls.

Presynaptic dopaminergic function in the putamen, but not in the caudate, was significantly higher in patients overall compared with controls, with a large effect size (ES; after correction for possible publica…