Discussion
psychotic symptoms, cognitive impairments
Our main finding is that the co-administration of CBD with THC had no effect on the induction of either cognitive impairments or psychotic symptoms following cannabis use. Similarly, CBD did not influence the subjective (as measured by VAS) or the pleasurable effects (music and chocolate) of THC. This was true across the range of CBD:THC dose ratios that are typically present in both recreational and medicinal cannabis [Using a within-subjects design minimised the potentially confounding effects of inter-individual differences in responses to THC and CBD [Including an additional placebo arm might have made it easier to establish the effects of THC. However, the focus of the study was to compare cannabis with different CBD:THC ratios, rather than to examine the effects of THC alone. The latter have been described in previous studies, and the cognitive and psychological effects of THC that we observed relative to baseline were in line with those reported relative to placebo in infrequent users [Our findings are consistent with previous reports that co-administration of CBD with THC did not alter the effects of THC on memory, psychotic symptoms [There are other mechanisms by which cannabis with higher CBD:THC ratios may be less harmful to users. The cannabis plant produces both THC and CBD (in their acid forms) from a precursor named cannabigerolic acid [