Molecular imaging

Abstract

The dopamine hypothesis of schizophrenia was a major early focus of clinical molecular imaging studies. Over the years, molecular imaging has provided support for increased activity of striatal presynaptic dopaminergic neurons, as well as guidelines for optimal clinical treatment with antipsychotic drugs. Research on brain neurotransmission markers in schizophrenia has been extended also to the serotonin, GABA and cannabinoid systems. More recently, following the increased interest in the immune system as a pathophysiological factor in schizophrenia, much effort has been invested in PET studies targeting the glial marker translocator protein (TSPO). Whereas early reports in small samples found evidence for an increase in TSPO, more recent work using radioligands with higher specific to non-specific binding ratio has indicated lower levels in patients. Generally, sample sizes in clinical molecular imaging studies have been small, such that many of the individual studies are underpowered to detect even medium-sized effects. Multisite collaborations and data sharing are important ways forwards to address this issue.