Neurophysiological effects of cannabinoids: implications for psychosis research

It is widely accepted that there is a close relationship between cannabis use, the endocannabinoid system, and psychosis. In particular, cannabis use has the potential to trigger the onset of psychosis in vulnerable individuals and to exacerbate psychotic symptomatology in schizophrenia patients, including positive, negative, and cognitive symptoms. With regard to the cognitive dysfunctions as a core feature of schizophrenia, overlapping deficits in the domains of attention, memory, and executive functioning have been observed between chronic cannabis use and the disease. In this overview, we report on human clinical and experimental studies investigating the acute and chronic effects of cannabinoids on specific neurophysiological measures, i.e., the P50 suppression, the mismatch negativity, and the P300 potential, that consistently showed characteristic abnormalities in schizophrenia. Based on the results, we discuss some explanations on the putative mechanisms involving the endocannabinoid system and its interactions with other neuromodulators that might form the neural substrates underlying cannabis-induced cognitive impairments and help understand the neurobiology underpinning the development of cognitive deficits in schizophrenia.