The following chapter offers an overview of results of experimental studies conducted among healthy individuals examining the effects of acute administration of Δ9-THC and other cannabinoids, alone or in combination, on brain function and behavior, also as a function of previous cannabis exposure. In light of their methodological design, these studies have advanced the understanding of the neurobiological mechanisms increasing the risk of long-lasting cognitive dysfunction as well as psychosis in regular cannabis users. Also, direct and indirect evidence supports an alteration of different neurotransmitters, such as dopamine, glutamate, and gamma-aminobutyric acid, in modulating the manifestation of neurocognitive dysfunction and psychosis in the context of both acute and chronic cannabis exposure. Future multimodal neuroimaging studies will integrate the longitudinal information to track the long-term changes in brain neurochemistry and neurophysiology as well as other potential biomarkers induced by sustained cannabis use.
