Molecular imaging of schizophrenia: Neurochemical findings in a heterogeneous and evolving disorder

The past four decades have seen enormous efforts placed on a search for molecular markers of schizophrenia using positron emission tomography (PET) and single photon computed (SPECT). In this narrative review, we cast broad net to define summarize what researchers learned about from imaging studies. Some PET studies brain energy metabolism with the glucose analogue FDGhave shown hypofrontality defect in patients schizophrenia, but more generally indicate loss metabolic coherence between different regions. An early finding significantly increased striatal trapping dopamine synthesis tracer FDOPA has survived meta-analysis many replications, increase is not pathognomonic disorder, since one half entirely normal capacity. Similarly, competition SPECT show greater basal amphetamine-evoked occupancy at post-synaptic D2/3 receptors difference likewise pathognomonic. We thus propose that neurochemical heterogeneity within diagnostic entity schizophrenia. Occupancy established relevant target engagement by antipsychotic medications living brain. There evidence elevated frontal cortical D1 receptors, especially relation cognitive deficits general lack consistent findings abnormalities serotonin markers, some decreased levels nicotinic patients. are sparse somewhat inconsistent reduced binding muscarinic, glutamate, opioid ligands, microglial activation, very recently, globally synaptic proteins One study reports decline histone acetylase confined dorsolateral prefrontal cortex. most contexts, phase disease effects or present medication can obscure confound