Of these , the metabolite produces the greatest psychoactive effects .
Cannabidiol ( CBD ) is not psychoactive but plays a modulating role on cannabis psychoactive effects .
The proportion of 9-THC in plant material is higher ( up to 40 % ) than in other cannabinoids ( up to 9 % ) .
Conclusions Findings reveal that 9-THC contributes the most to cannabis psychoactivity .
Due to lower psychoactive potency and smaller proportions in plant material , other psychoactive cannabinoids have a weak influence on cannabis final effects .
Objective This systematic review aims to summarize current evidence on which naturally present cannabinoids contribute to  cannabis psychoactivity  , considering their reported concentrations and pharmacodynamics in humans .
Interactions in man of delta‐9‐tetrahydrocannabinol; II. Cannabinol and cannabidiol
Oral doses of delta‐9‐tetrahydrocannabinol ( THC ) 20 mg , combined with placebo or with 40 mg doses of cannabinol ( CBN ) and cannabidiol ( CBD ) , were given to volunteers . The combination of THC with CBN produced no detectable changes in the quality , intensity , or duration of the effects of THC alone . The THC‐CBD combination tended to delay onset and prolong effects of THC , while making them somewhat more intense . Even this interactive effect was slight , providing no reason to ab and on the current practice of basing doses of marihuana for clinical studies solely on THC content
Of these , the metabolite produces the greatest psychoactive effects .
Cannabidiol ( CBD ) is not psychoactive but plays a modulating role on cannabis psychoactive effects .
The proportion of 9-THC in plant material is higher ( up to 40 % ) than in other cannabinoids ( up to 9 % ) .
Conclusions Findings reveal that 9-THC contributes the most to cannabis psychoactivity .
Due to lower psychoactive potency and smaller proportions in plant material , other psychoactive cannabinoids have a weak influence on cannabis final effects .
Objective This systematic review aims to summarize current evidence on which naturally present cannabinoids contribute to  cannabis psychoactivity  , considering their reported concentrations and pharmacodynamics in humans .