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. 2013 Oct 16;4:130. doi: 10.3389/fpsyt.2013.00130

Table 1.

Summary of “naturalistic” studies in which the effects of cannabidiol and cannabis with a high dosis of THC on psychological functions have been investigated.

Reference Subjects THC/CBD Results Remarks
Di Forti et al. (47) “First-episode” psychiatric patients (n = 280) Self reported frequency and type of cannabis used The chance that high-potent cannabis (THC) has been used is higher among “first-episode” psychotic patients than among non-psychotics Also more frequent use in “first-episode” psychotic patients
Morgan and Curran (45) Cannabis users (n = 154) Grouping based on presence of THC and/or CBD in hair More psychotic symptoms among THC group in comparison with no THC group and in group with THC and CBD in hair THC might be psychotogenic and CBD might protect against this effect
Schubart et al. (48) Websurvey among cannabis users (n = 1877) Grouping based on self reported preference for type of cannabis Less psychotic symptoms in cannabis users who use cannabis with high level of CBD (hash) Personal communication with author (Schubart)
Morgan et al. (46) Cannabis users, at least once a month (n = 134) Choosing cannabis by cannabis user Acute effects on mood, psychotic symptoms, and cognition CBD attenuates the THC-induced memory impairment; CBD does not affect psychotomimetic symptoms
Morgan et al. (49) Recreational cannabis users (n = 54) versus daily users (n = 66) Measuring THC and CBD in hair THC increases possibility of negative psychotic symptoms, CBD antagonizes (part of) THC-induced effects